sound travel in water

How far does sound travel in the ocean?

The distance that sound travels in the ocean varies greatly, depending primarily upon water temperature and pressure..

Water temperature and pressure determine how far sound travels in the ocean.

While sound moves at a much faster speed in the water than in air , the distance that sound waves travel is primarily dependent upon ocean temperature and pressure. While pressure continues to increase as ocean depth increases, the temperature of the ocean only decreases up to a certain point, after which it remains relatively stable. These factors have a curious effect on how (and how far) sound waves travel.

Imagine a whale is swimming through the ocean and calls out to its pod. The whale produces sound waves that move like ripples in the water. As the whale’s sound waves travel through the water, their speed decreases with increasing depth (as the temperature drops), causing the sound waves to refract downward . Once the sound waves reach the bottom of what is known as the thermocline layer, the speed of sound reaches its minimum. The thermocline is a region characterized by rapid change in temperature and pressure which occurs at different depths around the world. Below the thermocline "layer," the temperature remains constant, but pressure continues to increase. This causes the speed of sound to increase and makes the sound waves refract upward .  

The area in the ocean where sound waves refract up and down is known as the "sound channel." The channeling of sound waves allows sound to travel thousands of miles without the signal losing considerable energy.  In fact, hydrophones, or underwater microphones, if placed at the proper depth, can pick up whale songs and manmade noises from many kilometers away.

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More information.

• Noise in the Ocean: A National Issue (National Marine Sanctuaries)
• Just how noisy is the ocean? Learn about a NOAA Effort to Monitor Underwater Sound
• Sound in the Sea Gallery
• Acoustic Monitoring

Last updated: 01/20/23 Author: NOAA How to cite this article

June 27, 2019

What Do You Hear Underwater?

A submerged science activity from Science Buddies

By Science Buddies & Sabine De Brabandere

Make waves--underwater! Learn how sound travels differently in water than it does in the air. 

George Retseck

Key Concepts Physics Sound Waves Biology

Introduction Have you ever listened to noises underwater? Sound travels differently in the water than it does in the air. To learn more, try making your own underwater noises—and listening carefully. 

Background Sound is a wave created by vibrations. These vibrations create areas of more and less densely packed particles. So sound needs a medium to travel, such as air, water—or even solids. 

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Sound waves travel faster in denser substances because neighboring particles will more easily bump into one another. Take water, for example. There are about 800 times more particles in a bottle of water than there are in the same bottle filled with air. Thus sound waves travel much faster in water than they do in air. In freshwater at room temperature, for example, sound travels about 4.3 times faster than it does in air at the same temperature.

Sound traveling through air soon becomes less loud as you get farther from the source. This is because the waves’ energy quickly gets lost along the way. Sound keeps its energy longer when traveling through water because the particles can carry the sound waves better. In the ocean, for example, the sound of a humpback whale can travel thousands of miles!

Underwater sound waves reaching us at a faster pace and keeping their intensity longer seem like they should make us perceive those sounds as louder when we are also underwater. The human ear, however, evolved to hear sound in the air and is not as useful when submerged in water. Our head itself is full of tissues that contain water and can transmit sound waves when we are underwater. When this happens, the vibrations bypass the eardrum, the part of the ear that evolved to pick up sound waves in the air. 

Sound also interacts with boundaries between two different mediums, such as the surface of water. This boundary between water and air, for example, reflects almost all sounds back into the water. How will all these dynamics influence how we perceive underwater sounds? Try the activity to find out! 

Bathtub or swimming pool (a very large bucket can work, too)

Two stainless steel utensils (for example, spoons or tongs)

Two plastic utensils

Small ball 

Adult helper

An area that can get wet (if not performing the activity at a pool)

Floor cloth to cleanup spills (if not performing the activity at a pool)

Other materials to make underwater sounds (optional)

Access to a swimming pool (optional)

Internet access (optional)

Preparation

Fill the bathtub with lukewarm water—or head to the pool—and bring your helper and other materials.

Ask your helper to click one stainless steel utensil against another. Listen. How would you describe the sound? 

In a moment, your helper will click one utensil against the other underwater . Do you think you will hear the same sound? 

Ask your helper to click one utensil against the other underwater. Listen. Does the sound appear to be louder or softer? Is what you hear different in other ways, too?

Submerge one ear in the water. Ask your helper to click one utensil against the other underwater. Listen. How would you describe this sound? 

Ask your helper to click one utensil against the other underwater soon after you submerge your head. Take a deep breath, close your eyes and submerge your head completely or as much as you feel comfortable doing. Listen while you hold your breath underwater (come up for air when you need to!). Does the sound appear to be louder or softer? Does it appear to be different in other ways? 

Repeat this sequence but have your helper use two plastic utensils banging against each other instead.

Repeat the sequence again, but this time listen to a small ball being dropped into the water. Does the sound of a ball falling into the water change when you listen above or below water? Does your perception of this sound change? Why would this happen? 

Switch roles. Have your helper listen while you make the sounds. 

Discuss the findings you gathered. Do patterns appear? Can you conclude something about how humans perceive sounds when submerged in water? 

Extra : Test with more types of sounds: soft as well as loud sounds, high- as well as low-pitched sounds. Can you find more patterns?

Extra: To investigate what picks up the sound wave when you are submerged, use your fingers to close your ears or use earbuds when submerging your head. How does the sound change when you close off your ear canal underwater? Does the same happen when you close off your ear canal when you are above water? If not, why would this be different? 

Extra: Go to the swimming pool and listen to the sound of someone jumping into the water. Compare your perception of the sound when you are submerged with when your head is above the water. How does your perception change? Close your eyes. Can you tell where the person jumped into the water when submerged? Can you tell when you have your head above the water?

Extra: Research ocean sounds and how sounds caused by human activity impact aquatic animals.  

Observations and Results Was the sound softer when it was created underwater and you listened above the water? Did it sound muffled when you had only your ear submerged? Was it fuller when you had your head submerged? 

Sound travels faster in water compared with air because water particles are packed in more densely. Thus, the energy the sound waves carry is transported faster. This should make the sound appear louder. You probably perceived it as softer when you were not submerged, however, because the water surface is almost like a mirror for the sound you created. The sound most likely almost completely reflected back into the water as soon as it reached the surface. 

When you submerged only your ear, the sound probably still appeared muffled. This happens because the human ear is not good at picking up sound in water—after all, it evolved to pick up sound in air. 

When you submerged your head, the sound probably sounded fuller. That is because our head contains a lot of water, which allows the tissue to pick up underwater sound—without relying on the eardrum. It also explains why closing your ear canal makes almost no difference in the sound you pick up while you are underwater. 

If you tried to detect where the sound came from when submerged, you probably had a hard time. Our brain uses the difference in loudness and timing of the sound detected by each ear as a clue to infer where the sound came from. Because sound travels faster underwater and because you pick up sound with your entire head when you are submerged, your brain loses the cues that normally help you determine where the sound is coming from. 

More to Explore Discovery of Sound in the Sea , from the University of Rhode Island and the Inner Space Center Can You Hear Sounds in Outer Space? , from Science Buddies Talk through a String Telephone , from Scientific American Sound Localization , from Science Buddies  Ears: Do Their Design, Size and Shape Matter? , from Scientific American STEM Activities for Kids , from Science Buddies 

This activity brought to you in partnership with Science Buddies

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by Chris Woodford . Last updated: July 23, 2023.

Photo: Sound is energy we hear made by things that vibrate. Photo by William R. Goodwin courtesy of US Navy and Wikimedia Commons .

What is sound?

Photo: Sensing with sound: Light doesn't travel well through ocean water: over half the light falling on the sea surface is absorbed within the first meter of water; 100m down and only 1 percent of the surface light remains. That's largely why mighty creatures of the deep rely on sound for communication and navigation. Whales, famously, "talk" to one another across entire ocean basins, while dolphins use sound, like bats, for echolocation. Photo by Bill Thompson courtesy of US Fish and Wildlife Service .

Robert Boyle's classic experiment

Artwork: Robert Boyle's famous experiment with an alarm clock.

How sound travels

Artwork: Sound waves and ocean waves compared. Top: Sound waves are longitudinal waves: the air moves back and forth along the same line as the wave travels, making alternate patterns of compressions and rarefactions. Bottom: Ocean waves are transverse waves: the water moves back and forth at right angles to the line in which the wave travels.

The science of sound waves

Picture: Reflected sound is extremely useful for "seeing" underwater where light doesn't really travel—that's the basic idea behind sonar. Here's a side-scan sonar (reflected sound) image of a World War II boat wrecked on the seabed. Photo courtesy of U.S. National Oceanographic and Atmospheric Administration, US Navy, and Wikimedia Commons .

Whispering galleries and amphitheaters

Photos by Carol M. Highsmith: 1) The Capitol in Washington, DC has a whispering gallery inside its dome. Photo credit: The George F. Landegger Collection of District of Columbia Photographs in Carol M. Highsmith's America, Library of Congress , Prints and Photographs Division. 2) It's easy to hear people talking in the curved memorial amphitheater building at Arlington National Cemetery, Arlington, Virginia. Photo credit: Photographs in the Carol M. Highsmith Archive, Library of Congress , Prints and Photographs Division.

Measuring waves

Understanding amplitude and frequency, why instruments sound different, the speed of sound.

Photo: Breaking through the sound barrier creates a sonic boom. The mist you can see, which is called a condensation cloud, isn't necessarily caused by an aircraft flying supersonic: it can occur at lower speeds too. It happens because moist air condenses due to the shock waves created by the plane. You might expect the plane to compress the air as it slices through. But the shock waves it generates alternately expand and contract the air, producing both compressions and rarefactions. The rarefactions cause very low pressure and it's these that make moisture in the air condense, producing the cloud you see here. Photo by John Gay courtesy of US Navy and Wikimedia Commons .

Why does sound go faster in some things than in others?

Chart: Generally, sound travels faster in solids (right) than in liquids (middle) or gases (left)... but there are exceptions!

How to measure the speed of sound

Sound in practice, if you liked this article..., find out more, on this website.

• Electric guitars
• Speech synthesis
• Synthesizers

On other sites

• Explore Sound : A comprehensive educational site from the Acoustical Society of America, with activities for students of all ages.
• Sound Waves : A great collection of interactive science lessons from the University of Salford, which explains what sound waves are and the different ways in which they behave.

Educational books for younger readers

• Sound (Science in a Flash) by Georgia Amson-Bradshaw. Franklin Watts/Hachette, 2020. Simple facts, experiments, and quizzes fill this book; the visually exciting design will appeal to reluctant readers. Also for ages 7–9.
• Sound by Angela Royston. Raintree, 2017. A basic introduction to sound and musical sounds, including simple activities. Ages 7–9.
• Experimenting with Sound Science Projects by Robert Gardner. Enslow Publishers, 2013. A comprehensive 120-page introduction, running through the science of sound in some detail, with plenty of hands-on projects and activities (including welcome coverage of how to run controlled experiments using the scientific method). Ages 9–12.
• Cool Science: Experiments with Sound and Hearing by Chris Woodford. Gareth Stevens Inc, 2010. One of my own books, this is a short introduction to sound through practical activities, for ages 9–12.
• Adventures in Sound with Max Axiom, Super Scientist by Emily Sohn. Capstone, 2007. The original, graphic novel (comic book) format should appeal to reluctant readers. Ages 8–10.

Popular science

• The Sound Book: The Science of the Sonic Wonders of the World by Trevor Cox. W. W. Norton, 2014. An entertaining tour through everyday sound science.

Academic books

• Master Handbook of Acoustics by F. Alton Everest and Ken Pohlmann. McGraw-Hill Education, 2015. A comprehensive reference for undergraduates and sound-design professionals.
• The Science of Sound by Thomas D. Rossing, Paul A. Wheeler, and F. Richard Moore. Pearson, 2013. One of the most popular general undergraduate texts.

Text copyright © Chris Woodford 2009, 2021. All rights reserved. Full copyright notice and terms of use .

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How fast does sound travel through water?

Sounds travel faster through water than in air, but it takes more energy to get it going.

Sound is a wave of alternating compression and expansion, so its speed depends on how fast it bounces back from each compression – the less compressible the medium it’s travelling through, the faster it bounces back. Water is about 15,000 times less compressible than air, but it is also 800 times denser. The extra density means that the molecules accelerate more slowly for a given force, which slows the compression wave down. So water’s high density partly offsets its extreme incompressibility and sound travels at 1,493m/s, about four times faster than through air. The speed of sound in diamond is so high because it is extremely incompressible and yet relatively light.

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The basic components of a sound wave are frequency, wavelength and amplitude. In this example of a sound wave, the period of one cycle of this wave is 0.5 seconds, and the frequency of this wave is 2 cycles per second or 2 Hertz (Hz). Click image for larger view.

Click image to hear a scale of various frequencies (576 K, QuickTime). Click image for larger view.

Understanding Ocean Acoustics

Sharon Nieukirk, Research Assistant Acoustic Monitoring Project NOAA Pacific Marine Environmental Laboratory

What is Sound?

Ocean acoustics is the study of sound and its behavior in the sea. When underwater objects vibrate, they create sound-pressure waves that alternately compress and decompress the water molecules as the sound wave travels through the sea. Sound waves radiate in all directions away from the source like ripples on the surface of a pond. The compressions and decompressions associated with sound waves are detected as changes in pressure by the structures in our ears and most man-made sound receptors such as a hydrophone, or underwater microphone.

The basic components of a sound wave are frequency, wavelength and amplitude.

Frequency is the number of pressure waves that pass by a reference point per unit time and is measured in Hertz (Hz) or cycles per second. To the human ear, an increase in frequency is perceived as a higher pitched sound, while a decrease in frequency is perceived as a lower pitched sound. Humans generally hear sound waves whose frequencies are between 20 and 20,000 Hz. Below 20 Hz, sounds are referred to as infrasonic, and above 20,000 Hz as ultrasonic. The frequency of middle “C” on a piano is 246 Hz.

Wavelength is the distance between two peaks of a sound wave. It is related to frequency because the lower the frequency of the wave, the longer the wavelength.

Amplitude describes the height of the sound pressure wave or the “loudness” of a sound and is often measured using the decibel (dB) scale. Small variations in amplitude (“short” pressure waves) produce weak or quiet sounds, while large variations (“tall” pressure waves) produce strong or loud sounds.

The two examples below show sound waves that vary in frequency and amplitude.

These two waves have the same frequency but different amplitudes. Click image for larger view .

These two waves have the same amplitude but different frequencies. Click image for larger view.

The decibel scale is a logarithmic scale used to measure the amplitude of a sound. If the amplitude of a sound is increased in a series of equal steps, the loudness of the sound will increase in steps which are perceived as successively smaller. A decibel doesn’t really represent a unit of measure like a yard or meter, but instead a pressure value in decibels expresses a ratio between the measured pressure and a reference pressure. On the decibel scale, everything refers to power, which is amplitude squared. And just to confuse things, the reference pressure in air differs from that in water. Therefore a 150 dB sound in water is not the same as a 150 dB sound in air. So when you are describing sound waves and how they behave it is very important to know whether you are describing sound in the sea or in air.

Note on Acoustic Noise Level Units: Hydrophones measure sound pressure, normally expressed in units of micropascals (µPa). Early acousticians working with sound in air, realized that human ears perceive differences in sound on a logarithmic scale, so the convention of using a relative logarithmic scale (dB) was adopted. In order to be useful, the sound levels need to be referenced to some standard pressure at a standard distance. The reference level used in air (20µPa @ 1m) was selected to match human hearing sensitivity. A different reference level is used for underwater sound (1µPa @ 1m). Because of these differences in reference standards, noise levels cited in air do NOT equal underwater levels. To compare noise levels in water to noise levels in air, one must subtract 26 dB from the noise level referenced in water. For example, a supertanker radiating noise at 190 dB (re 1µPa @ 1m) has an equivalent noise level in air of about 128 dB (re 20µPa @ 1m). These numbers are approximate, and amplitude often varies with frequency.

Faster than the Speed of Sound...

The speed of a wave is the rate at which vibrations move through the medium. Sound moves at a faster speed in water (1500 meters/sec) than in air (about 340 meters/sec) because the mechanical properties of water differ from air. Temperature also affects the speed of sound (e.g. sound travels faster in warm water than in cold water) and is very influential in some parts of the ocean. Remember that wavelength and frequency are related because the lower the frequency the longer the wavelength. More specifically, the wavelength of a sound equals the speed of sound in either air or water divided by the frequency of the wave. Therefore, a 20 Hz sound wave is 75 m long in the water (1500/20 = 75) whereas a 20 Hz sound wave in air is only 17 m long (340/20 = 17) in air.

As we descend below the surface of the sea, the speed of sound decreases with decreasing temperature. At the bottom of the thermocline, the speed of sound reaches its minimum; this is also the axis of the sound channel. Below the thermocline the temperature remains constant, but pressure increases which causes the speed of sound to increase again. Sound waves bend, or refract, towards the area of minimum sound speed. Therefore, a sound wave traveling in the sound channel bends up and down and up and down and can travel thousands of meters. Click image for larger view.

The SOFAR Channel

Sound in the sea can often be “trapped” and effectively carried very long distances by the “deep sound channel ” that exists in the ocean. This SOFAR or SOund Fixing And Ranging channel is so named because it was discovered that there was a "channel" in the deep ocean within which the acoustic energy from a small explosive charge (deployed in the water by a downed aviator) could travel over long distances. An array of hydrophones could be used to roughly locate the source of the charge thereby allowing rescue of downed pilots far out to sea. Sound, and especially low-frequency sound, can travel thousands of meters with very little loss of signal. Read more information on the SOFAR channel.

The field of ocean acoustics provides scientists with the tools needed to quantitatively describe sound in the sea. By measuring the frequency, amplitude, location and seasonality of sounds in the sea, a great deal can be learned about our oceanic environment and its inhabitants. Hydroacoustic monitoring (listening to underwater sounds) has allowed scientists to measure global warming, listen to earthquakes and the movement of magma through the sea floor during major volcanic eruptions, and to record low-frequency calls of large whales the world over. As our oceans become more noisy each year, the field of ocean acoustics will grow and only become more essential. For more information and a tutorial on ocean acoustics .

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E-mail Updates | User Survey | Contact Us | Report Error On This Page | Privacy Policy | Disclaimer | Site Info | Site Index Revised August 26, 2022 by the NOAA Ocean Explorer Webmaster Office of Ocean Exploration and Research | National Oceanic and Atmospheric Administration | U.S. Department of Commerce http://oceanexplorer.noaa.gov/explorations/sound01/background/acoustics/acoustics.html

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Sound in water.

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Prof John Montgomery, the head of Auckland University Leigh Marine Laboratory, explains how sound travels in water and how this is different to how sound travels in air. He explains why sound can travel so much further in the ocean compared to on land.

Point of interest: In this clip. you’ll hear the ‘song’ of the humpback whale. The humpback whale song is known to travel large distances through the ocean.

PROF JOHN MONTGOMERY Sound in the marine environment hasn’t been that well studied, but we know, I guess, from our original work where the question was, we know that fish can detect reefs, but how do they detect it? And our hypothesis was that it was based on sound. So we went and tested that, and found that larval fish do orient towards reef sounds, so we could record reef sound on a reef, take it out into a place where there wasn’t a reef and it would show up thinking there was a reef there. So that gives a really good indication of the likely importance of the soundscape, that it may be an important cue for animals in terms of migrations to reefs.

One of the real advantages of sound from a biological point of view is that there is a lot of it there and that it travels really well. So it can give you information about things that are happening from long distances away, and clearly that’s important for all sorts of biological activity.

The main difference between sound in air and sound in water is that air is a far less dense medium, so it doesn’t take much to move air, but sound attenuates reasonably quickly with distance and air, whereas under water, you need a sound that’s intense enough to move the water, which is quite dense and heavy, but it’s not very compressible so the sound then will propagate long distances.

In water, marine creatures can hear sound from vast distances and the extreme is probably the song of the humpback whale. and that sound can travel across whole oceans. so you could get, potentially, humpbacks at one end of the Pacific listening to humpbacks at the other.

Acknowledgement: Canadian Broadcasting Corporation Andrew Stevenson http://www.youtube.com/watch?v=eOS20plm7UM

Sound on the move

Sound is a pressure wave, but this wave behaves slightly differently through air as compared to water. Water is denser than air, so it takes more energy to generate a wave, but once a wave has ...

Hearing sound

Three components are needed for sound to be heard: A source – where the sound is made. A medium – something for the sound to travel through. A receiver – something to detect the sound. Source ...

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Marine animals, including humpback whales, use underwater sound to communicate, navigate, find food and mates, and avoid predators. (Image credit: NOAA National Marine Sanctuary Program)

Soundcheck: Ocean noise

What is ocean noise, animals make noise and hear ours too, waterways getting busier, noisier, finding solutions.

The ocean has always been a noisy place. Many natural sources—like storms, earthquakes, and animals—create underwater sounds. But with the rise of the industrial age, levels of underwater noise from human activities—including from ships, sonar, and drilling—increased dramatically.

Not all sound is created equal. Sources of ocean noise vary in many ways, including how loud they are (intensity, measured in decibels), how long they last (fractions of a second to never ending), and their pitch or tone (frequency, measured in hertz). Think about frequencies relative to tones on a piano. Way down low on the bottom keys are the frequencies that most of the large whale species, as well as large numbers of fish species, use to communicate.

Those growing levels of ocean noise affect marine animals and habitats in complex ways. For one thing, sounds below the surface differ from noises you hear above the waves. Underwater, noises travel farther. In one experiment from the early 1990s, researchers placed a speaker near Antarctica, played some low-frequency or deep-pitched sounds, and picked up those sounds near Bermuda—demonstrating that sound can literally travel halfway around the world.

NOAA has a responsibility to protect marine species and their habitat, which is why we’re working with scientists around the world to further our understanding on ocean noise. Our data and information ultimately help government agencies and industries reduce effects on our ocean resources.

Noise comes in many flavors—ranging from short-term, loud bursts with potentially acute impacts, to long-term, lower level chronic degradation of the background noise environment. NOAA has a role in trying to understand and manage the effects from each.

Marine animals use underwater sound in many important ways. Just as people talk to each other, marine animals use sound to communicate. However, also like people, vocal marine species hear much more than the sounds they use to communicate with one another. Marine species use their hearing to find food and mates, avoid predators, and navigate. Sound is critical to the survival of a great many marine species.

These animals have had 40 to 50 million years or more to evolve in their acoustic environment. But with the advent of the industrial age, people have drastically altered the underwater soundscape over the course of roughly a century. And sometimes how people use the marine environment can affect daily life and functions of marine species.

For this reason, NOAA works with other federal agencies and industries, who are proposing projects that might affect marine species and their habitat—such as oil and gas exploration and drilling, construction, or military training activities—that create loud underwater sounds over specified periods of time. If those sounds could negatively affect marine animals or their habitat, NOAA can require measures and can recommend best practices to reduce negative effects. For example, some measures can avoid noisy activities in specific places when they are important to protected animals or are important to fishery species. Other measures seek to reduce noise exposure for sensitive ecosystems within areas of designated national significance, like National Marine Sanctuaries.

Global forecasts continue to suggest large increases in both the size and number of ships, which predict more noise to come.

Commercial shipping growth has greatly altered the soundscape. In some places, like off Central California, scientists see a strong relationship between growth in large commercial shipping fleets and measurements of lower frequency noise. They are the same frequencies used in the songs of male fin whales and blue whales and by spawning fish such as cod and haddock.

Because shipping traffic is such a major contributor to chronic noise, in 2014 the United States (with NOAA and the U.S. Coast Guard at the helm) led a group within the International Maritime Organization in ratifying voluntary guidelines on ways that ships can reduce noise. NOAA will continue to work with partners, including those within the shipping industry, to incentivize building new and retrofitting existing ships to be quieter.

We’re finding win-win solutions to some of our problems. For example, propellers can create bubbles underwater that burst with a signature sound. In addition to noise, those bubbles are thought to create fuel inefficiency. One question is whether a quieter propeller that produces less noise would also be more efficient to make up the difference in upfront cost. Because large shipping companies face pressure to comply with stricter carbon emission standards, propeller changes in tomorrow’s ships could help both shipping operators and the environment.

The United States is not alone in these efforts. Ports in British Columbia, Canada, are creating incentives for shipping companies to figure out how much noise they make compared to other ships and reward those with good environmental status.

NOAA is working with partners around the world to develop new tools to better understand the complexities of ocean noise and is developing strategies that help governments and industries address it.

Given NOAA’s mission to keep marine resources sustainable and resilient for future generations, we recognized the need to tackle the issue of man-made ocean noise in a holistic way. In 2010, NOAA committed to improve tools that the agency uses to assess the effects of man-made sound on whales, dolphins, and porpoises.

Current number of underwater reference stations in U.S. waters tracking ocean noise levels over time for the federal government. 

This led to two complementary efforts —one to produce maps of where these animals are located and in what densities within U.S. waters, and another to predict levels of underwater noise from human activities . Scientists can use these maps, along with other information, to better understand what is happening underwater and where higher levels of human-produced noise overlap with the marine mammals. With these maps complete, NOAA began to push forward on a long-term visionary plan regarding ocean noise effects.

In the fall of 2016, NOAA released our final Ocean Noise Strategy Roadmap . The strategy is a NOAA initiative that seeks to guide the agency toward more comprehensive and effective management of the effects of man-made ocean noise over the next decade. The Strategy includes steps to improve what we know about underwater noise, and how we can work to minimize adverse effects of ocean noise on marine species and habitats.

One basic thing we still need to learn more about is how noisy it is in different ocean soundscapes and how those levels are changing through time. This research is ongoing. In the meantime, we’re working with partners on new and innovative techniques to further reduce risk while noisy activities are happening, such as placing observers in the area to stop activities when marine mammals come within a certain distance. And in some cases, measures can be taken to make the activity itself quieter, through the application of quieting designs. Examples include using bubble curtains around a pile or using alternative quieter technologies instead of airguns.

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Understanding Sound in the Ocean

Levels of underwater noise from human activities—including from ships, sonar, and drilling—have increased dramatically. Those growing levels of ocean noise affect marine animals and habitats in complex ways.

Table of Contents

What types of sounds occur in the ocean, why is sound important to marine animals, does sound behave differently underwater than in air, what kinds of underwater sounds do people produce, how does the sound we produce affect marine species, what is noaa fisheries doing about sound in the ocean, how does noaa fisheries help protect marine life from the harmful impacts of ocean noise.

Both natural and human-made sounds occur in the ocean. Natural sounds come from marine life and naturally occurring events like underwater earthquakes. Human-made sounds come from many sources, such as ships, underwater energy exploration, military sonar, and underwater construction, among others.

Learn more about sound in the ocean .

Sound is essential to many types of marine animals and is one of the main tools they use to survive in the ocean. Light can only penetrate a few hundred feet underwater, but sound can travel much farther. As a result, cetaceans (whales, dolphins, and porpoises) have evolved over millions of years to send and receive a variety of complex sounds. They rely on sound to communicate with each other, navigate, find mates and food, defend their territories and resources, and avoid predators. Fish and invertebrates also use sound for basic life functions.

Because water is denser than air, sound travels faster and farther in the ocean. Its speed and distance depends on the density of the water (determined by its temperature, salinity, and depth) and the frequency of the sound, measured in hertz (Hz). Some sounds, particularly low-frequency ones, can cover vast distances, even across ocean basins.

People produce some sounds intentionally, such as military sonar and seismic tests for oil and gas exploration. Other sounds are an unintentional by-product of an activity, such as shipping and underwater construction. Many human-produced sounds in the ocean are intermittent, whereas shipping creates an almost constant rumble in the ocean. Even the motor of a fishing boat creates extra sound underwater.

All of these sounds add to overall ocean noise and contribute to the “soundscape,” which scientists define as the combined sounds made by humans, natural events, and marine animals. Because sound travels so well underwater, many of these sounds can be heard miles from their sources.

Depending on the sound source, duration, and location, human-caused sound has the potential to affect animals by:

• Causing temporary or permanent hearing loss.
• Causing a stress response.
• Forcing animals to move from their preferred habitat.
• Disrupting feeding, breeding/spawning, nursing, and communication behaviors.

The impacts may be immediate and severe, or they may accumulate over time.

We are engaged on several fronts to better understand and manage ocean sounds, specifically in regard to cetaceans and other types of marine life. Most recently, we published the Ocean Noise Strategy Roadmap which defines a 10-year plan for the agency to address ocean noise.

In 2011, we started the CetSound mapping project . CetSound provides two mapping tools: SoundMap and CetMap . SoundMap allows us to map the time and location of noise, and CetMap shows how many cetaceans are in a given area at a specific time. This information is used to determine where marine animals go to breed and find food, what routes they use to migrate, and where small or fixed populations are concentrated. We then have a better understanding of how ocean noise affects them.

NOAA Fisheries is also part of an interagency partnership that established a set of undersea listening stations around the United States to measure levels of background noise in the ocean.

Among many efforts to protect marine species, NOAA Fisheries administers the Endangered Species Act to recover threatened and endangered species and prevent their extinction. Through consultations under the ESA , we develop biological opinions  to determine how the actions of federal agencies may affect ESA-listed species and critical habitat .

We also are responsible for authorizing the “take” of marine mammals that can result from the sounds produced by human activities. These Incidental Take Authorizations are issued under the Marine Mammal Protection Act . The MMPA limits the numbers of animals that can be “taken” (disturbed or hurt) as a result of human activities and ensures that those activities result in a negligible impact on marine mammal species and stocks.

By knowing how much underwater noise humans produce around the world, scientists can develop ways to reduce or prevent it, as well as ways to protect marine animals from it.

Learn more about sound in the ocean and what NOAA is doing to reduce it to protect marine animals:

• NOAA's Ocean Noise Strategy  
• NOAA Fisheries' Ocean Acoustics Program  

Marine Mammal Acoustic Technical Guidance

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Sound is a form of energy transmitted through pressure waves; longitudinal or compressional waves similar to the seismic P-waves we discussed in section 3.3 . With ocean sounds, the energy is transmitted via water molecules vibrating back and forth parallel to the direction of the sound wave, and passing on the energy to adjacent molecules. Therefore, sound travels faster and more efficiently when the molecules are closer together and are better able to transfer their energy to neighboring particles. In other words, sound travels faster through denser materials. Since water is much denser than air, the speed of sound in water (about 1500 m/s) is approximately five times faster than the speed in air (around 330 m/s). This helps explain why we sometimes have difficulty localizing the source of a sound that we hear underwater. We localize sound sources when our brains detect the tiny differences in the time of arrival of sounds reaching our ears. A sound coming from our left will reach our left ear a fraction of a second before reaching our right ear. Our brains can process that small difference in time of arrival to recognize the direction from which the sound came. In water, the sound is so much faster that the difference in arrival time between our ears becomes too small for us to interpret, and we lose the ability to localize the source.

However, as with sound in air, the speed of sound in the ocean is not constant; it is influenced by a number of variables including temperature, salinity , and pressure, and an increase in any of these factors will lead to an increase in the speed of sound. We have seen that these variables change with depth and location; so to will the speed of sound differ in different regions of the ocean.

To examine the way the speed of sound changes as a function of depth, we need to consider the vertical profiles for temperature and pressure. At the surface, the pressure is low, but the temperature is at its highest point in the water column. The temperature effects dominate at the surface, so the speed of sound is fast in surface waters. As depth increases, the temperature and the speed of sound decline. Near the bottom, the extreme pressure dominates, and even though temperatures are low, the speed of sound increases with depth. At moderate depths (between a few hundred and one thousand meters) there is a zone where both temperature and pressure are relatively low, so the speed of sound is at a minimum. This zone of minimum speed is called the SOFAR channel ( So und F ixing A nd R anging) or the Deep Sound Channel (Figure 6.4.1).

The SOFAR channel is important because sounds produced in that region can be propagated over very long distances with little attenuation (loss of energy). Sound waves produced in the channel radiate out in all directions. Waves that travel into shallower or deeper water outside of the sound channel are entering a region of faster sound transmission. As we saw with seismic waves, when these sound waves encounter a region of differing transmission speed, the waves tend to be refracted or bent back towards the region of lower speed. As a result, sound waves moving from the SOFAR channel into shallower water will be refracted back towards the channel. As the sound waves go deeper below the channel, they will be refracted upwards, back into the channel and the region of slower speed. In this way, much of the sound does not dissipate out into the water in all directions, but instead is trapped within the channel, and can travel very long distances with little loss of energy (Figure 6.4.2).

There are several practical applications of the SOFAR channel. Baleen whales are thought to use the SOFAR channel to communicate with each other over long distances of hundreds to thousands of kilometers. Their vocalizations are very loud and are low frequency calls, which travel farther than high frequency sounds in the oceans. The military has been able to track submarines using the SOFAR channel, and during World War II it was used to locate downed pilots or missing ships and planes. A stranded pilot could drop a small device into the water, and once it sank into the SOFAR channel it would explode, creating a sound that could be heard at multiple listening stations. Using the time of arrival of the sound at the various receivers, the location of the source could be determined through triangulation. In the 1990s it was suggested that the SOFAR channel could be used to monitor global ocean temperatures. A project known as ATOC (Acoustic Thermometry of Ocean Climate) was proposed where loud, low frequency sounds produced near Hawaii and California would travel through the SOFAR channel to receiving stations around the Pacific. By monitoring the time it took for the sounds to reach the receivers, scientists could monitor changes in ocean temperatures on a global scale, as sounds would move faster through a warming ocean.

Since sound travels better through water than air, the energy required to transmit a given sound wave is higher in air than in water. The energy, or intensity (loudness) of a sound is measured on the decibel (dB) scale. It turns out that it takes about 61 times more energy to transmit a sound through air than through water. Because of this energy difference, there is a 61 dB difference between sounds transmitted through air and water, such that a sound intensity of 120 dB in water would be equivalent to an intensity of about 60 dB in air. This should be kept in mind when trying to compare sounds in the ocean with sounds in the air. A sound of 130 dB in air is about equivalent to standing 100 m from a jet engine at takeoff. A sound of 130 dB in water is equivalent to about 70 dB in air, which is the intensity of the sound of a vacuum cleaner. It should also be pointed out that on the dB scale, an increase of 10 dB means the sound is 10 times louder. In other words, 20 dB is 10 x louder than 10 dB, while 30 dB is 100 x louder than 10 dB.

• Discovery of Sound in the Sea website: http://www.dosits.org/

a seismic body wave that is characterized by deformation of the rock in the same direction that the wave is propagating (compressional vibration) (3.3)

mass per unit volume of a substance (e.g., g/cubic cm) (6.3)

the concentration of dissolved ions in water (5.3)

range of depths around 1000 m where sound travels the slowest, so sound waves are refracted back into the channel and can be propagated long distances (6.4)

Introduction to Oceanography Copyright © by Paul Webb is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

How does sound travel in shallow water?

Illustration of a side view of the continental shelf. Image public domain.

In the field of ocean acoustics, “shallow water” commonly refers to coastal waters extending from the shoreline out to the edge of the continental shelf to a depth of about 200 m, where the seafloor slope increases. By this definition, shallow water accounts for approximately 8% of the ocean and seas. These regions are important because they are close to human populations and account for much of the exclusive economic zones (EEZs) of coastal nations. These regions are important for marine habitats, fisheries, national security, commerce, energy development, and recreation.

The following sections include information on the structure of the shallow water sound channel by season (including the sea surface and seafloor), how sound travels in shallow water, and how the shallow water sound channel varies in different parts of the ocean.

The shallow water sound channel

Sound travel in shallow water, geographic variability of the shallow water sound channel.

Speed of sound in water profile when the speed of sound is constant. Credit DOSITS.

The speed at which sound travels in the ocean is faster with increasing temperature , salinity , and pressure (See How fast does sound travel? ). Shallow waters are often well mixed by wind and waves in the winter, with temperature and salinity largely independent of depth. As a result, sound speed is also often largely independent of depth. This is very different from deep water, where there is a minimum in sound speed at a depth of about 1000 m in mid-latitudes, forming a sound channel or waveguide through which sound can propagate over long distances without interacting with the sea surface or seafloor (See How does sound travel long distances? The SOFAR Channel ). In shallow water, sound travels on paths that interact with the seafloor and ocean waves at the sea surface.

Sound speed is largely independent of depth in shallow water in winter. This is particularly true in the mid-latitudes (for more information, see below on geographic variability). When sound speed is constant, sound travels in straight lines. Sound that travels upward from a source travels in a straight line until it hits the surface. Upon reaching the sea surface, the sound is reflected and travels back downward toward the seafloor (See How does sound move? Reflection ). Almost no sound travels into the air. Sound that travels down from a source propagates in a straight line until it hits the seafloor. Upon reaching the seafloor, some of the sound is reflected and travels back upward. Not all of the sound is reflected, however. Some of the sound travels into the seafloor.

The following figure has two parts. On the left is a plot of sound speed as a function of depth. Sound speed is the same at all depths. On the right are the paths followed by sound waves as they travel away from the source. These waves travel in straight lines until they are reflected at the sea surface or the sea floor.

Left: Constant speed of sound through the water column. Right: Paths followed by sound waves as they travel away from the source in shallow water at a constant sound speed. Credit DOSITS.

Vertical distances in this figure are greatly exaggerated compared to horizontal distances. This causes the angles from the horizontal at which sound waves travel to look much steeper than they really are.

Sound loses energy when it hits the ocean surface or seafloor. Whenever sound reflects from the rough ocean surface, some sound energy is scattered and lost. Similarly, whenever sound hits the rough seafloor, some sound energy is scattered and lost. In addition, some sound energy can travel into the seafloor and be attenuated . Absorption in the seabed is much greater than absorption in seawater [for more about absorption see Sound Absorption ].

Whether or not sound goes into the seafloor depends upon the angle to the horizontal at which the sound is traveling. When the sound speed in seafloor is greater than the sound speed in the water above it, which is usually the case, there is a special angle, called the critical angle . The critical angle is usually about 15º. When sound travels at angles to the horizontal that are smaller than the critical angle, the sound is almost perfectly reflected (shown in the blue line in the figure below). When sound travels at angles to the horizontal greater than the critical angle (shown in the yellow line in the figure below), some of the sound enters the seafloor. Sound that travels at angles greater than the critical angle disappears into the seafloor after a few reflections . This is the major source of energy loss in shallow water. Uncertainties in the properties of the seafloor, including sound speed, density , and attenuation , make it difficult to accurately predict how sound travels in shallow water.

An illustration of the reflection and refraction of sound waves when they encounter the seafloor at the critical angle and greater and less-than the critical angle. Credit DOSITS.

Sound waves traveling in the sound channel follow many different paths. Although sound travels away from a sound source in all directions, only sound traveling away from a source on paths that leave the source at specific angles will reach a receiver at a specific location.

Left: Constant speed of sound through the water column. Right: Illustration of the paths between a mid-depth source and a mid-depth receiver at a constant sound speed. Only the sound waves reaching the receive are shown. Credit DOSITS.

The sound waves traveling on different paths from source to receiver have slightly different travel times. A single impulsive source will therefore be heard as a number of separate arrivals. The sound that travels directly from the source to the receiver travels the shortest path and arrives first. Sounds that reflect from the sea surface or seafloor travel further and arrive later. This is different from sound propagation in deep water where the shortest path on the sound channel axis arrives last (See Sound Travel in SOFAR Chanel for more information).

The way in which sound speed changes with depth is not the same everywhere in shallow water because the ocean temperature and salinity profiles that determine sound speed can differ greatly from one location to another and from one time to another. The variability is much higher in coastal regions than in the deep ocean.

Sound speed is independent of depth in shallow water when wind and waves are strong, resulting in fully mixed conditions. This most often occurs in wintertime near the coast in water that is less than roughly 30 m deep. In summertime and in deeper waters further from the coast, the sun warms the water near the surface, but the warming does not extend all the way to the seafloor. Sound speed is higher in the warmer water near the surface than in the colder water near the seafloor. There are often three layers, with a mixed layer near the surface with relatively high sound speed, a layer in which temperature and sound speed decrease, and a cold layer above the seafloor with lower sound speed.

Left: Illustration of ray paths for a source located below the thermocline, showing the rays being refracted toward the seafloor when there is a summer thermocline. Right: Speed of sound through the water column when the speed is not constant. Credit DOSITS.

A sound wave traveling through the ocean is  refracted  (bent) whenever it encounters changes in the speed of sound (See How does sound move? Refraction ). Sound waves are continually refracted toward the region of lower sound speed. Differing sound-speed profiles therefore cause sound waves to travel on quite different paths. For a three-layer profile , sound that travels upward from a source located in the cold water near the seafloor is bent back towards the seafloor when it travels up into warmer water with higher sound speeds. The result is that the sound interacts repeatedly with the seafloor and rapidly becomes weaker.

In shallow water, sound speed often varies as a function of geographic location as well as depth. For instance, on the continental shelf off the east coast of the U.S., the water’s temperature and salinity are influenced by the Gulf Stream and associated eddies. These oceanographic features can form fronts between the colder shelf waters and warmer Gulf Stream current flow. Therefore, the sound speed profiles can be complicated, changing in time and space and resulting in complex acoustic propagation.

Graph of the sound speed on the shelf off the New Jersey shore. Image from Kristy A. Moore, James H. Miller, Gopu R. Potty, James F. Lynch and Arthur Newhall, “Investigation of three‐dimensional propagation effects at the New Jersey shelf break front,” Journal of the Acoustical Society of America 2007 121:5, 3126-3126.

Additional links on DOSITS

• Science of Sound > Sound Movement >  How fast does sound travel?
• Science of Sound > How does sound travel long distances? The SOFAR Channel
• Sound of Sound > Sound Movement > Reflection
• Sound of Sound > Sound Movement > Refraction
• Sound of Sound > Sound Movement > Absorption
• Sound of Sound > Sound Movement > Scattering
• Moore, K. A., Miller, J. H., Potty, G. R., Lynch, J. F., & Newhall, A. (2007). Investigation of three‐dimensional propagation effects at the New Jersey shelf break front . The Journal of the Acoustical Society of America , 121 (5), 3126–3126. https://doi.org/10.1121/1.4808487

Sound Transmission in the Ocean

The speed of sound depends on the medium through which sound waves propagate. The speed of sound differs in air and water, with sound waves traveling faster in water. For example, in air at a temperature of 18°C (64°F), the speed of sound is approximately 341 meters (1,120 feet) per second. In contrast, in salt water at approximately the same temperature, the speed of sound is approximately 1,524 meters (5,000 feet) per second.

The state properties of water (temperature and pressure) and the degree of salinity also affect the speed of sound. The propagation of sound waves in sea water can be directly affected by suspensions of particulate matter that can scatter, absorb, or reflect the waves. Laboratory experiments demonstrate that distilled water—water from which salts and other suspended particles have been removed—provides a medium in which the speed of sound exceeds the speed of sound in ocean water. The difference in the speed of transmission is significant—speed in distilled water may be 20 to 30 times that of speeds found in ocean water.

Because frequency and wavelength are inversely proportional characteristics of sound waves, low-frequency signals produce long sound wavelengths. These long-wavelength signals encounter fewer suspended particles as they pass through the medium and thus are not as subject to scattering, absorption, or reflection. As a result, low-frequency signals are able to travel farther without significant loss of signal strength. Naval communication systems utilize low-frequency, long-wavelength signals to enhance communications with submerged submarines.

Physical Differences Produce a "Sound Channel"

Within the ocean, the speed of sound varies with changes in depth that accompany normal changes in temperature and pressure. Specific combinations of temperature, pressure, and salinity may act to create shadow zones, or reflective layers, that are resistant to the propagation of sound waves. A specific set of conditions, however, also act to create a channel through which sound waves propagate at minimal speed but with minimal loss of strength. Similar to the transmission of light through fiber-optic cables, the refraction (bending) of sound waves by layers of water with varying temperature, pressure, and/or salinity allow the formation of a well-defined sound channel.

Although the oceans are not uniform bodies of water—there are currents of water with dramatic variations of temperature (such as the Gulf Stream) and salinity—the speed of sound in the deeper regions of the oceans is influenced more by high pressure. Conversely, at shallower depths, temperature plays the most dominant role in governing the speed of sound.

The greater the temperature of the water, the faster sound travels. Surface temperature variation can be significant with seasonal variations in the amount of sunlight (insolation) that can produce changes in near-surface temperatures that, in turn, affect the speed of sound in water near the ocean surface. When the near-surface layer is well mixed by currents and surface action, a resulting isothermal layer allows uniform propagation speeds for sound waves. Such isothermal layers are common in mid-latitude regions.

The SOFAR Channel

A temperature gradient exists when the temperature of the water decreases with increasing depth. The resulting thermocline shows a characteristic decrease in the speed of sound with decreasing temperature. However, at a depth of approximately 750 meters (2,460 feet), the variations in temperature become so slight that the water becomes essentially isothermal (of uniform temperature). From that point, the speed of sound is regulated more by changes in pressure that accompany the increasing depth.

Because sound wave transmission speed is directly proportional to pressure, the speed of sound increases as the pressure increases with depth. Accordingly, at the interface of the thermocline and the isothermal depths, there exists a region of minimal speed of sound. This interface creates a sound "pipeline," or "deep sound channel," within the oceans that allows the transmission of low-frequency sound over thousands of kilometers. This sound fixing and ranging (SOFAR) channel was discovered in 1943 by an American team led by Maurice Ewing and J. L. Worzel, and independently by Soviet physicist Leonid Brekhovskikh. Ewing and Worzel demonstrated that the SOFAR channel was capable of transmitting the low-frequency, long-wavelength sound waves produced by an explosion near the Bahama Islands to receivers stationed near the coast of Africa.

SOFAR channel depths also are a function of the depth and thickness (extent) of the thermocline. For example, SOFAR channels run nearer the surface in colder, polar seas.

Temperature and pressure affect water density, and the refraction of sound waves occurs at the interface of mediums (or layers within a medium) of differing density. Because of refraction, sound waves traveling through the SOFAR channel are deflected toward a region of lower velocity. Accordingly, waves traveling upward toward the surface, where the speed of sound increases with increasing temperature, deflect downward. Waves traveling toward deeper water, where the speed of sound increases with increasing pressure, are deflected upward.

Sound waves can be trapped effectively in the narrow SOFAR channel. Traveling at minimum velocity, the sound waves lose little energy, allowing the waves to propagate over distances in excess of 25,000 kilometers (15,500 miles).

Prior to the widespread use of GPS (global positioning system) equipment, the SOFAR channel also was used for navigation and the location of marine craft. Some scientists hypothesize that certain species of whales utilize the SOFAR channel to communicate mating calls over long distances.

Based on the known relationship of temperature changes to changes in the speed of sound, the Acoustic Thermometry of Ocean Climate (ATOC) project is attempting to provide data crucial to measurement of changes in global temperature. By measuring differences in the speed of sound transmitted over long distances (such as across the Pacific basin), data accumulated over a long timeframe should average out variations in temperature and salinity, enabling ATOC scientists to calculate changes in ocean temperature that may provide evidence related to questions regarding global warming.

SEE ALSO Marine Mammals ; Oceanography, Physical ; Sea Water, Physics and Chemistry of.

K. Lee Lerner

Bibliography

Baggeroer, A., and W. H. Munk. "The Heard Island Feasibility Test." Physics Today 45 (1992):30.

Munk, Walter, Peter Worcester, and Carl Wunsch. Ocean Acoustic Tomography. Cambridge, U.K.: Cambridge University Press, 1995.

Rossby, T., and D. C. Webb. "Observing Abyssal Motions by Tracking SwallowFloats in the SOFAR Channel." JMR 17 (1970):365.

Scripps Institution of Oceanography. Explorations 5, no. 2 (fall 1998).

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How Far Does Sound Travel: The Science of Acoustics

Do you ever stop to think about how sound travels? It’s an interesting phenomenon that occurs everyday and yet we often take it for granted. In this blog post, we will explore the science of acoustics and how sound travels. We will answer the question of how far sound can travel and how it is affected by different factors. Stay tuned for an in-depth look at this fascinating topic!

Nature Of Sound

Sound is a mechanical wave that is an oscillation of pressure transmitted through some medium, such as air or water. Sound can propagate through solids and liquids better than gases because the density and stiffness are greater. So how far does sound travel? In this article we will answer how sound travels and how to calculate how far it travels in different scenarios.

Sound Transmits Conception

A common misconception with regard to how sound transmits itself between two points (for example from speaker to ear) is that the source creates waves of compression in the surrounding gas which then proceed on their way at a constant speed until they strike something else; either another solid object or our ears . This analogy might be okay for describing what goes on at low frequencies but once we go beyond around 1000 Hz, the propagation of sound becomes far more complex.

At low frequencies (below around 1000 Hz), sound waves tend to travel in all directions more or less equally and bounce off objects like a rubber ball would. As frequency increases however, the directivity of sound increases as well. So high-frequency sounds are more likely to travel in a straight line between two points than low frequencies. This is why we can often hear someone calling from some distance away when there is loud music playing – because the higher frequencies carry further than the lower ones.

How Far Can Sound Travel

There are three ways that sound can be transmitted: through air, through water, or through solids. The speed of sound through each medium is different and depends on the density and stiffness of the material.

The speed of sound through air is about 343 m/s (or 760 mph), and it travels faster in warmer air than colder air. The speed of sound through water is about 1500 m/s, and it travels faster in salt water than fresh water. The speed of sound through solids is much faster than through either gases or liquids – about 5000-15000 m/s. This is why we can often hear someone coming before we see them – the sound waves are travelling through the solid ground to our ears!

Now that we know how sound propagates and how its speed depends on the medium, let’s take a look at how to calculate how far it will travel between two points. We can use the equation

distance = speed x time

For example, if we want to know how far a sound will travel in one second, we have:

distance = 343 m/s x 0.001 s = 343 m

So sound travels 1 kilometer in roughly 3 seconds and 1 mile in roughly 5 seconds.

Does Вecibel Level affect the Sound Distance?

The surface area around a sound source’s location grows with the square of the distance from the source. This implies that the same amount of sound energy is dispersed over a larger surface, and that the energy intensity decreases as the square of the distance from the source (Inverse Square Law).

Experts of Acoustical control says, that

For every doubling of distance, the sound level reduces by 6  decibels  (dB), (e.g. moving from 10 to 20 metres away from a sound source). But the next 6dB reduction means moving from 20 to 40 metres, then from 40 to 80 metres for a further 6dB reduction.

How Far Can Sound Travel In Real World

In real world, there are many factors that can affect how far a sound travels. Factors such as air density, temperature and humidity have an impact on its propagation; obstacles like buildings or mountains could also block some frequencies from going through while letting others pass (this happens because at high frequencies they behave more like waves).

Sounds can propagate through solids better than they can propagate through air because their density/stiffness are greater (this means that sound travels faster). In addition to this, we also know that it takes less time for a high frequency wave to reach us from its source compared with low frequencies. For example if there’s some kind of obstacle blocking our path then it might take longer for waves at higher frequencies than those below 1000 Hz to past them.

Can Sound Waves Travel Infinitely?

No. The higher the frequency of a sound wave, the shorter its wavelength becomes. As wavelength decreases, the amount of energy in a sound wave also decreases and eventually it dissipates completely. This is why we often can’t hear someone calling from very far away when there’s loud music playing – because the high frequencies are being blocked out by all the noise!

Can Sound Travel 20 Miles?

The air may be permeable to these lower-frequency, sub-audible sound waves generated by elephants. Some whale species’ frequencies might travel through seawater for 1500 kilometers or 900 miles.

How Far Can a Human Scream Travel?

The normal intelligible outdoor range of the male human voice in still air is 180 m (590 ft 6.6 in).

The Guiness World Record of the Farthest distance travelled by a human voice belongs the Spanish-speaking inhabitants of the Canary Island of La Gomera, is intelligible under ideal conditions at 8 km (5 miles).

In Conclusion

At the end of this blog post, you should have a better understanding of how sound travel and what factors affect it. If you want to learn more about acoustics and sounds, you can check out our resources here.

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How Does Water Affect Sound?

What Are Areas of Compression & Rarefaction in Waves?

Water affects sound waves in several ways. For example, they move several times faster through water than air, and travel longer distances. However, because the human ear evolved to hear in air, water tends to muffle sounds that are otherwise clear in air. Water can also "bend" sound, sending it on a zigzag path instead of a straight line.

Sound Waves and Water

Sound travels in the form of waves resulting from vibrations emanating from objects. If, by chance, an object is struck or moves, it creates a vibration. These disturbances also cause the surrounding molecules of a medium -- air, liquid or solid -- to vibrate. In turn, the ears receive the tremors of these different substances, which send signals to the brain. These are interpreted as “sounds.”

The production of sound is also the same underwater. When you strike an object, vibrations from the underwater object start to bump surrounding water molecules. The submerged human ear does not hear the sound as easily as above ground. It requires a high frequency or a really loud volume for the human ear to hear it.

Speed of Sound

The speed of sound waves depends on the medium used, not on the number of vibrations. Sound travels faster in solids and liquids, and slower in gases. The speed of sound in pure water is 1,498 meters per second, compared to 343 meters per second in air at room temperature and pressure. The compact molecular arrangement of solids and the closer arrangement of molecules in liquids make these molecules respond more quickly to the disturbances of neighboring molecules than in gases.

Temperature and Pressure

As in gases, the speed of sound underwater is also dependent on density and temperature. In gases, the velocity of molecules increase whenever temperature increases; like gases, sound waves travel faster as temperature increases. Unlike gases, water has a greater density because of its molecular arrangement. Thus, sound waves travel faster underwater as the wave bumps through -- and vibrates with more molecules.

Sound Refraction

Refraction is a complex phenomenon, involving the bending of sound waves as they speed up and slow down when traveling through different mediums. This goes unnoticed in everyday life, yet scientists consider this property important in underwater oceanic study. The speed of sound in the ocean varies. As the ocean gets deeper, the temperature decreases while pressure increases. Sound travels faster at lower depths than at surface level, no matter how sizable the difference in temperature, due to pressure differences. The change in speed changes the direction of the waves, making it hard to determine where the sound originally came from.

Sound and Salinity

Salinity can also be a factor in determining the behavior of sound. In seawater, sound travels up to 33 meters per second faster than in freshwater. Salinity affects sound speed at the surface, especially at river mouths or estuaries. Sound travels faster in the ocean because there are more molecules -- specifically salt molecules -- for waves to interact with, as well as higher surface temperatures.

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About the Author

Steve Johnson is an avid and passionate writer with more than five years of experience. He's written for several industries, including health, dating and Internet marketing, as well as for various websites. He holds a bachelor's degree from the University of Texas.

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March 24, 2022

Warming oceans will significantly alter how sound travels underwater

by American Geophysical Union

Climate change will significantly alter how sound travels underwater, potentially affecting natural soundscapes as well as accentuating human-generated noise, according to a new global study that identified future ocean "acoustic hotspots." These changes to ocean soundscapes could impact essential activities of marine life.

In warmer water, sound waves propagate faster and last longer before dying away.

"We calculated the effects of temperature, depth and salinity based on public data to model the soundscape of the future," said Alice Affatati, an bioacoustics researcher at the Memorial University of Newfoundland and Labrador in St. John's, Canada, and lead author of the new study, published today in Earth's Future , AGU's journal for interdisciplinary research on the past, present and future of our planet and its inhabitants. It is the first global-scale estimate of ocean sound speed linked to future climate.

Two hotspots, in the Greenland Sea and a patch of the northwestern Atlantic Ocean east of Newfoundland, can expect the most change at 50 and 500 meter depths, the new study projected. The average speed of sound is likely to increase by more than 1.5%, or approximately 25 meters per second (55 miles per hour) in these waters from the surface to depths of 500 meters (1,640 feet), by the end of the century, given continued high greenhouse gas emissions (RCP8.5).

"The major impact is expected in the Arctic, where we know already there is amplification of the effects of climate change now. Not all the Arctic, but one specific part where all factors play together to give a signal that, according to the model predictions , overcomes the uncertainty of the model itself," said author Stefano Salon, a researcher at the National Institute of Oceanography and Applied Geophysics in Trieste, Italy.

The ocean soundscape is a cacophony of vibrations produced by living organisms, natural phenomena like waves and cracking ice, and ship traffic and resource extraction. Sound speed at 50 meters depth ranges from 1,450 meters per second in the polar regions to 1,520 meters per second in equatorial waters (3,243 to 3,400 miles per hour, respectively).

Many marine animals use sound to communicate with each other and navigate their underwater world. Changing the sound speed can impact their ability to feed, fight, find mates, avoid predators and migrate, the authors said.

Changing soundscapes

In addition to the notable hotpots around Greenland and in the northwestern Atlantic Ocean, the new study found a 1% sound speed increase, more than 15 meters per second, at 50 m in the Barents Sea, northwestern Pacific, and in the Southern Ocean (between 0 and 70E), and at 500 m in the Arctic Ocean, Gulf of Mexico, and southern Caribbean Sea.

Temperature, pressure with increasing depth and salinity all affect how fast and how far sound travels in water. In the new study, the researchers focused on hotspots where the climate signal stood out clearly from the model uncertainty and was larger than seasonal variability.

The new study also modeled common vocalizations, under the projected future conditions, of the North Atlantic right whale , a critically endangered species inhabiting both north Atlantic acoustic hotspots. The whales' typical "upcall" at 50 Hertz is likely to propagate farther in a warmer future ocean, the researchers found.

"We chose to talk about one megafauna species, but many trophic levels in the ocean are affected by the soundscape or use sound," Affatati said. "All these hotspots are locations of great biodiversity."

Future work will combine the global soundscape with other maps of anthropogenic impacts in the oceans to pinpoint areas of combined stressors, or direct needed observational research.

"With complicated problems like climate change , to combine different approaches is the way to go," said author Chiara Scaini, an environmental engineer at the National Institute of Oceanography and Applied Geophysics.

Provided by American Geophysical Union

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Does Sound Travel Faster in Water or Air?

Most people, whether they are students or workers, have a pretty clear idea of how sound works. After all, who hasn’t heard about sound waves, vibrations, and other similar concepts? Yet, there are a few notions that still baffle people to this day, particularly regarding the way sound propagates in water and air. And, with so much contradictory information online, it’s easy to see why.

So, if you’re one of the many who want to know if sound travels faster in water or air, this article has got you covered. But first, let’s start with the basics!

» QUICK NAVIGATION «

What Is Sound?

Generally speaking, sound is a type of longitudinal mechanical wave that travels through a medium. However, there are two definitions regarding how sound is produced.

For starters, in physiology, sound is created when an object’s vibrations travel through a medium until they reach the human eardrum . In physics, sound is produced in the form of a pressure wave . More specifically, when objects vibrate, they cause the nearby molecules to also vibrate, triggering a chain reaction of sound wave vibrations in the specific medium.

But no matter which definition you prefer, you’ll notice a similarity — sound needs a medium to propagate and will not travel through a vacuum. As a matter of fact, sound travels at different speeds depending on the medium. In other words, the medium’s density and compressibility directly affect the speed of sound. For instance, sound waves will travel slower in a less dense and more compressible medium .

How Fast Does Sound Travel in Water?

When it comes to water, sound can travel as fast as 1,498 meters per second, or approximately 3,350 miles per hour . However, as mentioned earlier, the physical characteristics of the medium highly affect the speed.

As a result of its high salinity, seawater, such as oceans, allows sound to travel up to 33 meters per second faster than the freshwater found in lakes . That’s because salt molecules respond quickly to the disturbances of neighboring molecules, propagating sound waves faster and at longer distances.

The speed of sound is also dependent on density. As you might already know, water has an impressive density due to its unique molecular arrangement. Thus, sound waves can travel much faster underwater as the wave bumps and vibrates with more molecules.

Temperature and Pressure

You need to understand that, as the ocean gets deeper, its temperature decreases and its pressure increases. These affect the particle arrangement and, by extension, the speed of sound. To put it simply, sound travels slower at the surface level than at lower depths.

How Fast Does Sound Travel in Air?

Sound is able to travel through the air at an average of 332 meters per second, or 742 miles per hour. Although that might seem fast, it is not nearly as fast as light , which travels at 186,411.358 miles per hour. But as with water, there are also many factors that affect how sound propagates in the air:

Temperature

Air molecules tend to have more energy at higher temperatures, meaning that they will vibrate faster. That allows sound waves to also travel faster and farther , as they are propelled by molecule collisions. Yet, as the sound moves through the atmosphere, some parts of its wave will travel faster than others due to temperature differences.

What’s interesting about sound is that, at a constant temperature, its speed is not dependent on the pressure of the medium. That’s because these two properties are tied to one another. So, increasing temperature will also increase pressure and, consequently, the speed of sound.

Air Direction

The wind direction can impact the speed of sound and the distance it can travel . In fact, you might notice that sound levels are higher when the wind is blowing down, such as from a highway towards the ground level.

Water vapors are less dense than dry air at a constant temperature. Naturally, the presence of moisture will decrease the air’s density and increase the speed of sound. Therefore, humid environments experience much faster sound propagation than dry and cold areas.

Why Does Sound Travel Faster in Water Than Air?

By now, you might have noticed that sound travels about four times faster in water than in air. The main reason behind this is that water is denser than air. Sure, not all water has identical properties , as salinity and temperature vary and affect its density. But even so, molecules in the water are closer together, causing more vibrations to be transmitted at a faster speed of sound.

Furthermore, water is an incompressible environment . Actually, it’s better to imagine water as being similar to a solid object, as they tend to behave similarly when it comes to compression. More specifically, when water encounters a force, it will immediately transfer its energy to nearby molecules, just like solids. This characteristic is partially offset by the water’s high density, creating the perfect environment for sound to travel through.

And lastly, it’s important to mention that sound travels faster in harder materials . It’s true that water as a unit is not necessarily hard; however, it has a strong bond between its molecules. Hence, the propagation of sound is faster as it passes more quickly from one particle to the next.

But Why Is It Harder to Talk to Someone Underwater?

Naturally, you might assume that, since sound travels faster in water, it would be incredibly easy to chat with someone while swimming or diving . But that couldn’t be further from the truth.

When someone talks, they do so by emitting air and sending compression waves through it. That’s thanks to your lungs, vocal cords, and mouth, which work together to imprint a sound waveform on the burst of air that comes from your body. So, in order for someone that’s in the water to hear you, the sound will need to travel from your mouth into the surrounding water.

However, sound couples very poorly from air to water. As a matter of fact, water tends to reflect external sound waves instead of allowing them to penetrate its surface. That’s also the reason why phenomenons like echos occur when you scream or talk near a well, as the water at its bottom reflects the sound waves back to you.

What About Sound Travel Distance?

When it comes to sound travel, water is again the clear winner, as it allows sound to propagate to distances of almost 15,500 miles. To understand why that’s the case, imagine a whale that is swimming through the ocean and calls out to its peers. The sound waves it produces move similarly to ripples in the water.

As the sound travels and reaches increasing depths , it begins to slow down and eventually refracts downward. Once the sound reaches a region called the thermocline layer, its speed further decreases to a minimum. That’s because the thermocline layer features rapid changes in pressure and temperature.

After breaking through the layer, sound waves encounter another area where the temperature remains constant. However, the pressure continues to rise, which causes a boost in the sound speed, making it refract upward. This channeling of waves allows the sound to travel thousands of miles with little to no energy loss. It’s thanks to this process that scientists can pick up whale songs from many miles away.

Key Takeaways

Understanding how sound works and travels is extremely important. Sure, you might not deal with mediums like water every day. However, air is all around you, and learning the way it affects sound speed can help you figure out the perfect way to soundproof your environment and enjoy a noise-free life!

RELATED POSTS:

• Does Sound Travel Faster Than Light?
• Does Sound Travel Up Or Down?
• How To Keep Sound In A Room
• Best Sound Absorbing Materials
• By Soundproof Living

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8 Best Headphones for Working Out, Tested & Reviewed

Finally, audio gear that isn't scared of a little sweat.

We've been independently researching and testing products for over 120 years. If you buy through our links, we may earn a commission. Learn more about our review process.

There’s nothing more frustrating than watching one of your earbuds fall out in the middle of a half-marathon or an intense HIIT workout. To avoid this pesky scenario from reoccurring, it might be time to consider swapping out your beloved earbuds for headphones that are designed for working out . That is, headphones that actually stay put securely inside your ear canal and don’t slip out when you start moving.

Fortunately, most workout headphones also feature waterproof or water-resistance ratings so if you’re caught in the rain or tend to get really sweaty, you don’t have to worry about any damage. Below, our pros have narrowed down the best headphones for working out to help you get in the zone, including various types of designs that are comfortable yet secure.

Our top picks:

Best Overall Headphones for Working Out

Beats fit pro.

Best Value Headphones for Working Out

Soundcore by anker space one.

Best Open-Ear Headphones for Working Out

Shokz openrun pro.

Best Versatile Headphones for Working Out

Apple airpods pro (2nd generation) with magsafe charging case (usb-c).

Best Premium Headphones for Working Out

Sony wh-1000xm5.

Best Innovative Headphones for Working Out

Bose ultra open earbuds.

Best Waterproof Headphones for Working Out

Jabra elite 8 active.

Best Stylish Headphones for Working Out

Beats solo 3.

According to our testing data, consumer feedback and hands-on reviews, these are the best headphones to bring with you on your next workout. Once you’ve scrolled through our top picks, check out more of our favorite earbuds for working out and head to the bottom for tips on shopping for workout headphones.

Beats are popular among runners and athletes for their excellent sound quality, comfortable fit and fantastic connectivity to iPhones (they feature the same Apple H1 chip found in certain AirPods). Our fitness experts like the Beats Fit Pro in particular, a Good Housekeeping Fitness Awards winner, for their wingtips that help keep the earbuds inside your ears as you move around. We also love that they feature noise cancellation so you can focus on your set of squats.

“I truly have never heard music sound so clear and sharp with in-ear headphones before,” raved one tester. “I also loved the sound cancellation capabilities — as soon as I put them in, the whole world went quiet.” With up to 24 hours of battery life with the carrying case, you shouldn’t have to recharge too frequently. Our Lab experts note, however, that their IP rating is a bit lower than other headphones designed for working out so be mindful to not get stuck under a summer downpour since they’re not 100 percent waterproof.

These over-ear headphones may be relatively cheap compared to other picks on this list, but that doesn't mean that they don't perform. They even made our list of best noise cancelling headphones for their exceptional value. With a claimed battery life of up to 40 hours (or 55 hours with noise cancelling off!) you won't have to recharge frequently. But what our tech experts love most is that they're super lightweight, portable and intuitive to use .

Sound quality isn't quite as impressive as more premium headsets, but they performed moderately well in Lab tests and effectively canceled out outside noise. Sadly, though, these aren't water-resistant and can retain heat so they're best suited for indoor sessions only or lighter training days.

These open-ear headphones from SHOKZ are perfect for anyone who likes to be mindful of their environment when running or working out, whether outdoor or indoors. Because they don’t actually sit inside your ear, audio is delivered through your cheekbones via bone conduction technology so you can both listen to music and listen to your gym buddy. When testing them out ourselves during workouts, we were impressed with their audio quality and found them to be both secure and comfortable.

“I ran outside and indoors on a treadmill and wasn’t scared they would fall out of my ears,” said one tester. Though we do wish that their carrying case was a bit more portable and featured recharging capabilities, the 10 hours of claimed battery life should be sufficient for at least a few outdoor runs.

Though we don’t necessarily think AirPods are the very best headphones for working out, this list wouldn’t be complete without them. Why? Because AirPods are some of the most convenient and versatile headphones out there . Not only do they connect seamlessly to iPhones, but they’re lightweight and feature an impressive battery life combined with their charging case.

We don’t recommend dunking them into a swimming pool, but they are water- and sweat-resistant so you should have no issues taking them on a jog through some light rain. Plus, because they feature noise cancelling you can effectively block out your gym environment (or tune in when you’re on a run and need to hear incoming traffic).

But despite all the reasons to get AirPods, there’s one thing to keep in mind: Their fit may not be as secure or comfortable as other earbuds, meaning that the AirPods could occasionally fall out.

The audio experts at the Good Housekeeping Institute can’t get enough of these over-ear headphones from Sony, a 2024 Family Travel Awards winner. Not only did the XM5 impress our pros in our most recent Lab tests for their pristine sound quality and superior noise cancellation , but we also found them super comfortable to wear no matter the activity.

Though they can trap heat, according to some testers, touch controls were intuitive and responsive — a big pro when you’re holding a weight in one hand but need to pause your music. You’ll get up to 24 hours of claimed battery life so you don’t have to worry about the battery dying on you, just keep in mind that they’re not as easy to transport as super compact earbuds and there’s no IP rating listed.

Though we haven’t yet tested these latest headphones from Bose in the Media & Tech Lab, Bose products have performed exceptionally well in Lab tests over the years and their latest innovations like the QuietComfort Ultra continue to impress us. What sets these headphones apart from existing Bose audio gear is that they feature an open, cuff-like design that reminds us of earrings . Like other open-ear headphones, you’ll be able to listen to your tunes as well as what’s going on around you.

Claimed battery life is solid with the combined carrying case at up to 27 hours total, and you can count on Bose to deliver fantastic sound quality. If, however, you’re not yet sold on an open-ear design and would prefer to have noise cancellation, our pros recommend considering the Bose QuietComfort Earbuds II , a GH tester favorite.

Every time our pros have tried on Jabra headphones, we’ve been impressed by just how comfortable and secure they feel. The Elite 8 Active are no exception and should be suitable for a variety of users thanks to three silicone ear tips that are provided. What’s unique about this pair is that it features some of the best claimed battery life you’ll find on the market, i.e., 32 hours with ANC on or a whopping 56 hours with ANC off once combined with their charging case.

On top of noise cancelling capabilities, these are water-, dust- and sweat-proof and designed for the toughest workouts, according to Jabra. They feature the highest IP rating of any headphones on this list, or IP68, which means that they’ve been tested to survive being submerged in up to one meter of water for 30 minutes!

It would be difficult to look any cooler at the gym than with the Beats Solo 3 , which feature a sleek, minimalist design. Sadly these aren’t water-resistant so we wouldn’t recommend getting them soaked, but we do think they’ll do a good job of blocking out the hustle and bustle of the gym so you can concentrate on your sets. Unlike other headphones on this list, the Solo 3 are noise isolating, which means that they don’t actually feature any noise cancellation but do effectively block out noise.

Though our pros warn that they can feel tight after extended use for some, that also means that they're super secure and don’t budge . On top of their long battery life, what we love about them is how portable they are for over-ear headphones. The Beats collapse into a compact size and come with a lightweight carrying case that’s perfect for bringing to your workout. Plus, the main control button is both intuitive and easy to use.

How we test the best headphones for working out

The experts and engineers at the Good Housekeeping Institute Media and Tech Lab have been testing earbuds and headphones for types of activity for more than a decade. In the past five years alone, we've logged over 300 hours of listening time and in our most recent evaluations, more than 20 pairs of headphones and earbuds were tested .

To test headphones for working out, our pros first assess each pair's ease of use. We evaluate how quickly the headphones pair to devices, as well as how intuitive on-ear controls are when listening to music, podcasts and more (for instance, is it easy to adjust volume, turn noise cancellation on or off, and skip tracks?). We also consider how comfortable the headphones feel while wearing them, taking note of their fit and design and how well they stay in-ear (or over-ear) during workouts.

To evaluate performance, our engineers run a variety of tests to assess sound quality, noise-canceling capabilities and audio spectrum analysis, when applicable. We also consider the headphones' battery life, charging time and durability when dropped or put in contact with water. Lastly, we factor in real-world consumer tester feedback to better understand headphones' overall sound quality, comfort and ease of use and setup.

What to look for when shopping for the best headphones for working out

✔️ Comfort, design and fit: It’s important that headphones for working out are not only comfortable, but that they feel secure inside your ears. You don’t want one earbud falling out as you’re on the treadmill, and you certainly don’t want your ears to start hurting after only 30 minutes. To find the best fit for you, consider whether you prefer over-ear or in-ear headphones. In-ear headphones typically come with adjustable tips so you can swap them out to the right size if they don’t feel secure. Also don’t forget about open-ear headphones, which can be a great alternative for anyone who wants a hybrid experience.

✔️ Water resistance: Exercise is typically associated with sweat, and sometimes sudden rainfall. To prevent any future damage to your new audio gear, it’s best to invest in a pair that has been tested to withstand sweat and water. Though your headphones don’t have to be waterproof, you'll ideally want ones that are water-resistant (unless you don't think you'll sweat significantly). To find out, check for an IP (ingress protection) rating. You’ll want one that’s at least IPX4, which means that your headphones have been tested to withstand water exposure. The first number refers to solids such as dust and sand, while the second number refers to liquids. Generally speaking, the higher the number, the more durable your headphones will be.

✔️ Battery life: Though battery life isn’t quite as important for workout headphones as it is for travel headphones (no one wants to be stuck on a plane without audio), it’s still essential to consider. Marathon runners or long-distance runners will benefit from long battery life on a single charge, and frequent gym goers will be pleased with a carrying case that recharges their headphones overnight so they don’t have to plug them in as frequently.

✔️ Noise cancellation: Whether or not you need noise cancellation is up to you. This technology is designed to produce a mirror image sound wave in your ear to cancel out external noise, meaning that you won’t be able to hear your surroundings (the drone of a treadmill, someone dropping weights, etc.). While some fitness enthusiasts may prefer hearing their environment, others might find it easier to focus on an intense training session without any distractions. Keep in mind that headphones featuring noise cancellation will typically cost more than those that do not.

Should you workout with headphones or earbuds?

The right answer comes down to personal preference. Some fitness enthusiasts may prefer the lighter feel of earbuds. They’re also typically much more portable and take up less room in a gym bag. However, earbuds can have a tendency to fall out of ears whereas a pair of over-ear headphones may feel more secure. Generally over-ear headphones will have improved noise cancellation capabilities, which is something to keep in mind if tuning out your environment is a priority to you. Just note that over-ear headphones may retain more heat and can start to feel sweaty during an intense cardio session. Also, they typically don’t feature as much waterproofing or sweat-resistance as earbuds.

Why trust Good Housekeeping?

For decades, the Good Housekeeping Institute has been providing expert reviews and feedback on the best electronics and accessories you can buy. Writer and Product Reviews Analyst Olivia Lipski covers everything from tech to fitness, travel, home, health and more. Not only does she bring years of product review experience to GH (she's reviewed everything from AirPods alternatives to JBL earbuds ), but since joining in 2021 she tests at least 25 pairs of earbuds and headphones per year and rotates them out as travels, walks her dog or commutes to the Hearst Tower.

Olivia (she/her) is a media and tech product reviews analyst at the Good Housekeeping Institute , covering tech, home, auto, health and more. She has more than five years of experience writing about tech trends and innovation and, prior to joining GH in 2021, was a writer for Android Central, Lifewire and other media outlets. Olivia is a graduate of George Washington University, with a bachelor's degree in journalism, political science and French, and she holds a master’s degree in communications from Sciences Po Paris.

@media(max-width: 64rem){.css-o9j0dn:before{margin-bottom:0.5rem;margin-right:0.625rem;color:#ffffff;width:1.25rem;bottom:-0.2rem;height:1.25rem;content:'_';display:inline-block;position:relative;line-height:1;background-repeat:no-repeat;}.loaded .css-o9j0dn:before{background-image:url(/_assets/design-tokens/goodhousekeeping/static/images/Clover.5c7a1a0.svg);}}@media(min-width: 48rem){.loaded .css-o9j0dn:before{background-image:url(/_assets/design-tokens/goodhousekeeping/static/images/Clover.5c7a1a0.svg);}} Product Reviews

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How the Key Bridge Collapsed in Baltimore: Maps and Photos

By Weiyi Cai ,  Agnes Chang ,  Lauren Leatherby ,  Lazaro Gamio ,  Leanne Abraham and Scott Reinhard

On Tuesday, a major bridge in Baltimore collapsed into the water seconds after it was struck by a cargo ship, sending vehicles on the bridge into the river below. The ship lost power and issued a mayday call shortly before it hit the bridge.

The ship, a 948-foot-long cargo vessel called Dali, was about a half hour into its journey toward Colombo, Sri Lanka, when it hit a main pillar of the bridge. All crew members are safe, according to the ship’s owners.

Follow our live coverage .

A mayday call from the ship gave officials enough time to stop traffic at both ends of the bridge. The waters where the bridge collapsed are about 50 feet deep. By Tuesday morning, six construction workers who had been fixing potholes on the bridge remained missing as divers and other emergency workers on boats and helicopters continued to search for them. Two others had been rescued, and one was in the hospital.

Francis Scott

Patapsco River

The ship left the Port

of Baltimore around

1 a.m. on Tuesday.

Where impact occurred

Direction of the ship

The ship hit the

bridge at 1:28 a.m.

The ship hit the bridge at 1:28 a.m.

Where impact

Source: Spire Global

The New York Times; satellite image by Google Earth

The lights of the ship flickered on and off as it lost power in the minutes before the ship changed bearing and hit the bridge.

Ship approached from

the Port of Baltimore

Road repair crews

Ship changed heading

as it neared pillar

Ship hit pillar

Southern and central spans

of bridge began to collapse within

seconds of impact

Northern span began to

collapse seconds later

Within 30 seconds of impact,

the central part of bridge had

entirely collapsed.

Source: StreamTime Live via YouTube

Timestamps are from StreamTime Live video.

The New York Times

The Francis Scott Key Bridge was opened in 1977 and carried more than 12.4 million vehicles last year. The bridge was one of the three major ways to cross the Patapsco River and formed part of Baltimore’s beltway.

The Port of Baltimore is a major trade hub that handled a record amount of foreign cargo last year. It is an especially important destination — the nation’s largest by volume last year — for deliveries of cars and light trucks.

Ship impact

To Chesapeake Bay

Sources: Maryland Port Administration, OpenStreetMap, MarineTraffic

Note: Ship positions are as of 2:46 p.m. Eastern time.

Overall, Baltimore was the 17th biggest port in the United States in 2021, ranked by total tons, according to the Bureau of Transportation Statistics. The bridge collapse brought marine traffic there to a standstill, with seven cargo or tanker ships stranded in the harbor as of Tuesday afternoon.

Gov. Wes Moore declared a state of emergency for Maryland and said that his office was in close communication with Pete Buttigieg, the U.S. transportation secretary. The White House issued a statement saying that President Biden had been briefed on the collapse.

Erin Schaff/The New York Times

• Share full article

Half dozen popular swim sites flunk water-quality tests

WASHINGTON, N.C. (WITN) - An Eastern Carolina environmental group says a half dozen recreational sites have too much bacteria.

The latest Sound Rivers water-quality tests were taken this week.

“We collected samples on Thursday, when much of central and eastern North Carolina was in the middle of a significant rain event, so it’s not surprising that some sites had extremely elevated levels of E. coli. Stormwater runoff can carry a lot of bacteria into our waterways,” said Clay Barber, program director for Sound Rivers.

On the Tar-Pamlico, Havens Gardens in Washington and Port Terminal in Greenville failed the Swim Guide water-quality test. On the Neuse, Buffaloe Road and Poole Road in Raleigh, Clayton River Walk in Clayton, and Midyette Street in Oriental also failed.

From Memorial Day to Labor Day, Sound Rivers tests more than 50 sites each week. During the fall, winter, and spring, the group scales that back to just 18 locations each month.