how does sound travel through air experiment

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• TeachEngineering
• Traveling Sound

Hands-on Activity Traveling Sound

Grade Level: 4 (3-5)

Time Required: 30 minutes

Expendable Cost/Group: US $2.00

Group Size: 2

Activity Dependency: None

Subject Areas: Physical Science, Reasoning and Proof, Science and Technology

NGSS Performance Expectations:

Curriculum in this Unit Units serve as guides to a particular content or subject area. Nested under units are lessons (in purple) and hands-on activities (in blue). Note that not all lessons and activities will exist under a unit, and instead may exist as "standalone" curriculum.

• Seeing and Feeling Sound Vibrations
• Pitch and Frequency
• Sound Visualization Stations

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Engineering connection, learning objectives, materials list, worksheets and attachments, more curriculum like this, pre-req knowledge, introduction/motivation, vocabulary/definitions, troubleshooting tips, activity extensions, activity scaling, user comments & tips.

Sound and acoustic engineers know that the shape of a room and its materials greatly impact how sound waves travel. Recording studios are designed in soundproof booths so that the recorded music does not contain any unwanted external noise. Libraries are designed to reduce any introduced noises, to assure a quiet, non-distracting learning environment. Concert halls are designed so that sound generated on the stage travels to the back of the space without being distorted.

After this activity, students should be able to:

• Explain that sound can move through solids, liquids and gases.
• Describe how sound needs molecules to move and that changing the medium that it travels through changes the sound.
• Describe how engineers use sound energy when designing spaces, such as movie theaters.

Educational Standards Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards. All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN) , a project of D2L (www.achievementstandards.org). In the ASN, standards are hierarchically structured: first by source; e.g. , by state; within source by type; e.g. , science or mathematics; within type by subtype, then by grade, etc .

Ngss: next generation science standards - science, international technology and engineering educators association - technology.

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State Standards

Colorado - science.

Each group needs:

• large bowl (metal works best)
• 2 metal objects, such as spoons, to knock together
• Traveling Sound Worksheet , one per student

A basic understanding of the phases of matter: liquids, solids and gases.

Sound engineers are especially interested in the way sound travels. Can you hear as well when you sit in the back of the class as when you sit in the front? What about in the assembly hall or gymnasium? On the playground? Can you think of other times when you cannot hear as well as someone else? What happened? How about in a movie theater? What do engineers do so that the sound quality is good for everyone in a movie theater? (Possible answers: Add speakers around the room, curtains, carpet the walls, cone-shaped theaters act like a megaphone and help to direct sound waves further.)

Which is louder—walking on carpet or on tile? It is quieter on carpet because the carpet absorbs the sound energy . Sound energy, light energy and other types of energy, need molecules to travel through and vibrate , but sometimes sound energy is absorbed by an object or material. Engineers use this idea when designing rooms that are meant to be quiet. Have you ever noticed how the walls of a movie theater are covered with carpet or fabric? This is to prevent echoing of the sound system. Sometimes when you are in an empty room, your voice echoes or sounds hollow. This is because an empty room has no materials in it that might absorb the sound energy, so the sound bounces off the hard walls, back at you. This makes it hard to hear clearly.

Do you think sound energy can travel through air? Of course it can! That is how sound energy travels when you talk to a friend. How about water? Can you hear sound travel under water? How about a solid? Can sound move through a solid object? Engineers want to know if sound can travel through solids, liquids and gases so they can develop ways to send messages to people all over the world. Can you imagine how great sound would be if it could travel anywhere?

Understanding the properties of sound and how sound waves travel helps engineers determine the best room shape and construction materials when designing libraries, classrooms, sound recording studios, concert halls and theatres. Room shape and materials can impact how sound waves travel since sound waves bounce off different object in different ways. In this activity, we are going to study how sound waves travel through liquids, solids and gases, and think about how engineers might use this information.

Before the Activity

• Gather materials and make copies of the Traveling Sound Worksheet .
• Divide the class into teams of two students each.

With the Students

• Ask the students to predict if sound can move through solids, liquids and gases.
• Have the students complete the worksheet, which leads them through traveling sound wave activities.
• Can sound energy travel through solids? Students place their ears on a desk or table as they tap or scratch on the top. They compare that to the same sound made when their ear is not pressed to the table.
• Can sound energy traveling through liquids? Fill a large bowl or bucket (metal works best) with water. One student taps two spoons together under the water. Two other students observe and compare the tapping sound they hear, as heard through the air and as heard by placing an ear against the bowl.
• Can sound energy traveling through gases (air)? The students feel their throats gently during each of these tasks:
• Hum with your mouth and nose open.
• Hum with your mouth open and nose closed.
• Hum with your mouth closed and nose open.
• Hum with your mouth and nose closed.
• Discuss with the students what happened. Were their predictions correct? Can sound travel through air, water and solids? (Answer: Yes!) Sound needs molecules to move. Solids, liquids and gases are all made of molecules. The characteristics of the molecules (for example, the space between the molecules) determine whether the sound becomes muffled or changes in some way.
• How might engineers use the knowledge that sound travels through solids, liquids and gases? (Possible answers: Engineers create devices that send sound anywhere — through water to a submarine in the ocean, through wires to your TV, and through the air in surround sound movie theaters or emergency broadcast signals.)

echo: Repetition of a sound by reflection of sound waves from a surface.

frequency: The rate of vibrations in different pitches.

pitch: The highness or lowness of a sound.

sound energy: Audible energy that is released when you talk, play musical instruments or slam a door.

sound wave: A longitudinal pressure wave of audible or inaudible sound.

vibration: When something moves back and forth, it is said to vibrate. Sound is made by vibrations that are usually too fast to see.

volume: When sound becomes louder or softer.

wave: A disturbance that travels through a medium, such as air or water.

Pre-Activity Assessment

Prediction: Ask students if they think sound can move through solid, liquid, and gas. If so what are some examples? (Possible examples: Students may recall talking under water or using tin can and string telephones.)

Activity Embedded Assessment

Worksheet: Have students use the Traveling Sounds Worksheet to guide them in the activity and as a place to record their observations. Review their answers to gauge their mastery of the subject.

Post-Activity Assessment

Toss-a-Question:  Ask students to independently think of an answer to the question below and write it on a half sheet of paper. Have students wad up and toss the paper to another team member who then adds their answer idea. After all students have written down ideas, have them toss the paper wad to another team, who reads the answers aloud to the class. Discuss answers with the class.

• What is an example of something through which sound can travel?

Neighbor Check: Have the students compare their activity observations with a neighbor. Are they the same or different? Have each team report some of their similar and dissimilar observations to the rest of the class.

Engineering Design: The supply of air on Earth is running out! Several futuristic cities for human habitation are being designed either underwater or deep inside mountains. Have each student group become a city planning engineering team and draw a communication system for sending emergency messages between the new cities. Make sure to illustrate and describe how the sound energy (message) will move through air, water or solid rock.

This activity can be very loud. Ask students to not disturb others while they learn and have fun.

To bring some humor to the activity, ask each student to hum a small part of their favorite song while feeling their throat. Have each student alternate between having their nose and mouth open or closed while humming non-stop. Why does the sound change depending on whether you close your nose or mouth? What happens if you block your ears? What does this activity teach us about sound? (Answer: Sound vibrations must travel through air for us to hear them. Like a musical instrument [perhaps a recorder or flute], if you change the holes where sound escapes, it changes the pitch, but not the frequency/vibrations of the sound.)

If a metal bowl is used during the activity, the vibrations from the objects colliding underwater vibrate the bowl, creating the illusion that the bowl is being struck. Have students draw the vibrations in the bowl on a piece of paper. Do the vibrations change if the objects are tapped together increasing softly?

Have students think about different forms of communications. Does sound travel most often through solids, liquids or gases? Have students poll their friends, family and neighbors to solicit their ideas.

For lower grades, conduct the activities as a class instead of in teams. Younger students could also draw pictures of their observations instead of writing in sentence form.

Students are introduced to the sound environment as an important aspect of a room or building. Several examples of acoustical engineering design for varied environments are presented.

Students learn how different materials reflect and absorb sound.

Students learn that sound is energy and has the ability to do work. Students discover that sound is produced by a vibration and they observe soundwaves and how they travel through mediums. They understand that sound can be absorbed, reflected or transmitted.

Students use the engineering design process to design and create soundproof rooms that use only one type of material. They learn and explore about how these different materials react to sound by absorbing or reflecting sound and then test their theories using a box as a proxy for a soundproof room. ...

Dictionary.com. Lexico Publishing Group, LLC. Accessed December 19, 2005. (Source of some vocabulary definitions, with some adaptation.) http://www.dictionary.com

Contributors

Supporting program, acknowledgements.

The contents of this digital library curriculum were developed under grants from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation (GK-12 grant no. 0338326). However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: March 17, 2021

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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..., don't want to read our articles try listening instead, 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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Sound on the move.

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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 started, it will travel faster than it would do in air.

A relay race

Sound travels by particles bumping into each other as they vibrate. It is a little like a relay race – each runner holds a little bit of information (the baton), and when they make contact with the next runner, they pass the information on.

In the case of sound, the runners are particles and the information (baton) they are passing along is energy of vibration. In a sound wave, a particle picks up some energy and keeps it until it bumps into a neighbouring particle. The next particle will then pick up the energy and transfer it to the next one in the chain. This happens extremely fast and is detected as a wave of pressure.

Sound won’t travel in a vacuum because there are no particles to bump together to transmit the vibration.

Sound in air

In a gas like air, the particles are generally far apart so they travel further before they bump into one another. There is not much resistance to movement so it doesn’t take much to start a wave, but it won’t travel as fast.

Sound in water

In water, the particles are much closer together, and they can quickly transmit vibration energy from one particle to the next. This means that the sound wave travels over four times faster than it would in air, but it takes a lot of energy to start the vibration. A faint sound in air wouldn’t be transmitted in water as the wave wouldn’t have enough energy to force the water particles to move.

Sound in solids

In a solid, the particles are even closer together and linked by chemical bonds so the wave travels even faster than it does in either liquid or air, but you need quite a lot of energy to start the wave at the beginning.

Sound and temperature

Temperature has a marked influence on the speed of sound. This is not due to a change in how closely together the particles are to each other but relates to the amount of energy that each particle has. Hot particles have more energy and transmit sound better than cold particles. Water in Antarctica will transmit sound slower than water in the tropics.

Some comparisons for the speed of sound in different materials

Related content.

Explore the science concept related to sound further with these articles:

• Hearing sound – the basics of sound waves
• Measuring sound – the different parts of a sound wave, how we talk about and measure sound
• Sound – visualising sound waves – helps students to 'see’ sound waves with videos and diagrams

In our recorded PLD session Sounds of Aotearoa a group of primary science educators introduce some fun ways you can learn and teach about sound.

Activity ideas

Use these activities to explore some essential physics ideas relating to sound, but in a whole new way.

• Modelling waves with slinkies – stay indoors and model how sound travels.
• Catching worms using ground sounds – go outdoors and investigate whether there is any evidence that earthworms respond to vibrations in the ground.
• Sound detectives – can you locate sounds while blindfolded?
• Make and use a hydrophone – and listen to underwater sounds.
• Sound on an oscilloscope – use oscilloscope software and your computer to make and watch a visual sound display.
• Investigating sound – simple exploratory activities and questions to experience and build an understanding of sound.
• Hearing sounds – using whispers and vibrations to hear and experience how sound moves.
• Hearing sounds under water – go underwater yourselves to listen to sounds
• Measuring the speed of sound – use a timing app to measure the speed of sound.

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Sound as a Longitudinal Wave

• Sound is a Mechanical Wave
• Sound is a Longitudinal Wave
• Sound is a Pressure Wave

Sound waves in air (and any fluid medium) are longitudinal waves because particles of the medium through which the sound is transported vibrate parallel to the direction that the sound wave moves. A vibrating string can create longitudinal waves as depicted in the animation below. As the vibrating string moves in the forward direction, it begins to push upon surrounding air molecules, moving them to the right towards their nearest neighbor. This causes the air molecules to the right of the string to be compressed into a small region of space. As the vibrating string moves in the reverse direction (leftward), it lowers the pressure of the air immediately to its right, thus causing air molecules to move back leftward. The lower pressure to the right of the string causes air molecules in that region immediately to the right of the string to expand into a large region of space. The back and forth vibration of the string causes individual air molecules (or a layer of air molecules) in the region immediately to the right of the string to continually vibrate back and forth horizontally. The molecules move rightward as the string moves rightward and then leftward as the string moves leftward. These back and forth vibrations are imparted to adjacent neighbors by particle-to-particle interaction. Other surrounding particles begin to move rightward and leftward, thus sending a wave to the right. Since air molecules (the particles of the medium) are moving in a direction that is parallel to the direction that the wave moves, the sound wave is referred to as a longitudinal wave. The result of such longitudinal vibrations is the creation of compressions and rarefactions within the air.

Regardless of the source of the sound wave - whether it is a vibrating string or the vibrating tines of a tuning fork - sound waves traveling through air are longitudinal waves. And the essential characteristic of a longitudinal wave that distinguishes it from other types of waves is that the particles of the medium move in a direction parallel to the direction of energy transport.

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