Sound WavesExplores waves emanating into a material from a vibrating object.

Define sound. Describe sound waves and how they are generated. Identify media through which sound waves can travel.

Crack! Crash! Thud! That’s what you’d hear if you were in the forest when this old tree cracked and came crashing down to the ground. But what if there was nobody there to hear the tree fall? Would it still make these sounds? This is an old riddle. To answer the riddle correctly, you need to know the scientific definition of sound.

Defining SoundIn science, sound is defined as the transfer of energy from a vibrating object in waves that travel through matter. Most people commonly use the term sound to mean what they hear when sound waves enter their ears. The tree above generated sound waves when it fell to the ground, so it made sound according to the scientific definition. But the sound wasn’t detected by a person’s ears if there was nobody in the forest. So the answer to the riddle is both yes and no!

How Sound Waves BeginAll sound waves begin with vibrating matter. Look at the first guitar string on the left in theFigure below. Plucking the string makes it vibrate. The diagram below the figure shows the wave generated by the vibrating string. The moving string repeatedly pushes against the air particles next to it, which causes the air particles to vibrate. The vibrations spread through the air in all directions away from the guitar string as longitudinal waves. In longitudinal waves, particles of the medium vibrate back and forth parallel to the direction that the waves travel. You can see an animation of sound waves traveling through air at this URL: http://www.mediacollege.com/audio/01/sound-waves.html

Q: If there were no air particles to carry the vibrations away from the guitar string, how would sound reach the ear?A: It wouldn’t unless the vibrations were carried by another medium. Sound waves are mechanical waves, so they can travel only though matter and not through empty space.

A Ticking ClockThe fact that sound cannot travel through empty space was first demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air

out of the jar. The clock was still ticking, but the ticking sound could no longer be heard. That’s because the sound couldn’t travel away from the clock without air particles to pass the sound energy along. You can see an online demonstration of the same experiment—with a modern twist—at this URL: http://www.youtube.com/watch?v=b0JQt4u6-XI

Sound Waves and MatterMost of the sounds we hear reach our ears through the air, but sounds can also travel through liquids and solids. If you swim underwater—or even submerge your ears in bathwater—any sounds you hear have traveled to your ears through the water. Some solids, including glass and metals, are very good at transmitting sounds. Foam rubber and heavy fabrics, on the other hand, tend to muffle sounds. They absorb rather than pass on the sound energy.Q: How can you tell that sounds travel through solids?A: One way is that you can hear loud outdoor sounds such as sirens through closed windows and doors. You can also hear sounds through the inside walls of a house. For example, if you put your ear against a wall, you may be able to eavesdrop on a conversation in the next room—not that you would, of course.

Summary In science, sound is defined as the transfer of energy from a vibrating object in waves that travel

through matter. All sound waves begin with vibrating matter. The vibrations generate longitudinal waves that travel

through matter in all directions. Most sounds we hear travel through air, but sounds can also travel through liquids andsolids.

Explore MoreWatch the video “How Sound Waves Travel” at the following URL. Then explain how sound waves begin and how they travel, using the human voice as an example.http://www.youtube.com/watch?v=_vYYqRVi8vY

Review1. How is sound defined in science? How does this definition differ from the common meaning of the

word?2. Hitting a drum, as shown in the Figure below, generates sound waves. Create a diagram to show how

the sound waves begin and how they reach a person’s ears.

3. How do you think earplugs work?

Speed of SoundThe speed at which sound travels through a material.

Give the speed of sound in dry air at 20 °C. Describe variation in the speed of sound in different media. Explain the effect of temperature on the speed of sound.

Has this ever happened to you? You see a flash of lightning on the horizon, but several seconds pass before you hear the rumble of thunder. The reason? The speed of light is much faster than the speed of sound.

What Is the Speed of Sound?The speed of sound is the distance that sound waves travel in a given amount of time. You’ll often see the speed of sound given as 343 meters per second. But that’s just the speed of sound under a certain set of conditions, specifically, through dry air at 20 °C. The speed of sound may be very different through other matter or at other temperatures.

Speed of Sound in Different MediaSound waves are mechanical waves, and mechanical waves can only travel through matter. The matter through which the waves travel is called the medium (plural, media). The Table below gives the speed of sound in several different media. Generally, sound waves travel most quickly through solids, followed by liquids, and then by gases. Particles of matter are closest together in solids and farthest apart in gases. When particles are closer together, they can more quickly pass the energy of vibrations to nearby particles. You can explore the speed of sound in different media at this URL:http://www.ltscotland.org.uk/resources/s/sound/speedofsound.asp?strReferringChannel=resources&strReferringPageID=tcm:4-248291-64

Medium (20 °C) Speed of Sound Waves (m/s)

Dry Air 343

Water 1437

Wood 3850

Glass 4540

Aluminum 6320

Q: The table gives the speed of sound in dry air. Do you think that sound travels more or less quickly through air that contains water vapor? (Hint: Compare the speed of sound in water and air in the table.)A: Sound travels at a higher speed through water than air, so it travels more quickly through air that contains water vapor than it does through dry air.

Temperature and Speed of SoundThe speed of sound also depends on the temperature of the medium. For a given medium, sound has a slower speed at lower temperatures. You can compare the speed of sound in

dry air at different temperatures in the following Table below. At a lower temperature, particles of the medium are moving more slowly, so it takes them longer to transfer the energy of the sound waves.

Temperature of Air Speed of Sound Waves (m/s)

0 °C 331

20 °C 343

100 °C 386

Q: What do you think the speed of sound might be in dry air at a temperature of -20 °C?A: For each 1 degree Celsius that temperature decreases, the speed of sound decreases by 0.6 m/s. So sound travels through dry, -20 °C air at a speed of 319 m/s.

Summary The speed of sound is the distance that sound waves travel in a given amount of time. The speed of

sound in dry air at 20 °C is 343 meters per second. Generally, sound waves travel most quickly through solids, followed by liquids, and then by gases. For a given medium, sound waves travel more slowly at lower temperatures.

Explore MoreAt the following URL, read about the speed of sound in different materials. Be sure to play the animation. Then answer the questions below. http://www.ndt-ed.org/EducationResources/HighSchool/Sound/speedinmaterials.htm

1. Describe what you hear when you play the animation. Explain your observations.2. Name two properties of materials that affect the speed of sound waves. How do they affect the speed

of sound?3. Explain why sound waves moves more quickly through warmer air than cooler air.

Review1. What is the speed of sound in dry air at 20 °C?2. Describe variation in the speed of sound through various media.3. Explain how temperature affects the speed of sound.

Intensity and Loudness of SoundExplores how the amount of energy present in a sound changes how we perceive it.

Define intensity of sound and relate it to loudness. Compare decibel levels of different sounds. Identify factors that affect sound intensity.

A friend whispers to you in a voice so soft that she has to lean very close so you can hear what she’s saying. Later that day, your friend shouts to you from across the gymnasium. Now her voice is loud enough for you to hear her clearly even though she’s several meters away. Obviously, sounds can vary in loudness.

It’s All About EnergyLoudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity of the sound waves. Intensity is a measure of the amount of energy in sound waves. The unit of intensity is the decibel (dB).

Decibel LevelsThe Figure below shows decibel levels of several different sounds. As decibel levels get higher, sound waves have greater intensity and sounds are louder. For every 10-decibel increase in the intensity of sound, loudness is 10 times greater. Therefore, a 30-decibel “quiet” room is 10 times louder than a 20-decibel whisper, and a 40-decibel light rainfall is 100 times louder than the whisper. High-decibel sounds are dangerous. They can damage the ears and cause loss of hearing.

Q: How much louder than a 20-decibel whisper is the 60-decibel sound of a vacuum cleaner?A: The vacuum cleaner is 10,000 times louder than the whisper!

Amplitude and DistanceThe intensity of sound waves determines the loudness of sounds, but what determines intensity? Intensity results from two factors: the amplitude of the sound waves and how far they have traveled from the source of the sound.

Amplitude is a measure of the size of sound waves. It depends on the amount of energythat started the waves. Greater amplitude waves have more energy and greater intensity, so they sound louder. For a video demonstration of the amplitude and loudness of sounds, go to this URL: http://www.youtube.com/watch?v=irqfGYD2UKw

As sound waves travel farther from their source, the more spread out their energy becomes. You can see how this works in the Figure below. As distance from the sound source increases, the area covered by the sound waves increases. The same amount of energy is spread over a greater area, so the intensity and loudness of the sound is less. This explains why even loud sounds fade away as you move farther from the source.

This diagram represents just a small section of the total area of sound waves spreading out from a source. Sound waves actually travel away from the source in all directions.Q: Why can low-amplitude sounds like whispers be heard only over short distances?A: The sound waves already have so little energy that spreading them out over a wider area quickly reduces their intensity below the level of hearing.

Summary Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined,

in turn, by the intensity, or amount of energy, in sound waves. The unit of intensity is the decibel (dB). As decibel levels get higher, sound waves have greater intensity and sounds are louder. For every 10-

decibel increase in the intensity of sound, loudness is 10 times greater. Intensity of sound results from two factors: the amplitude of the sound waves and how far they have

traveled from the source of the sound.

Explore MoreReview sound intensity, loudness, and decibels at the following URL. Then answer the Check Your Understanding questions at the bottom of the Web page. Be sure to check your answers. http://www.physicsclassroom.com/class/sound/u11l2b.cfm

Review1. Define loudness and intensity of sound. How are the two concepts related?2. What is the unit of intensity of sound?3. At what decibel level do sounds start to become harmful to the ears and hearing?4. Relate amplitude and distance to the intensity and loudness of sound.

Frequency and Pitch of SoundExplores how the frequency of a sound affects how we perceive it.

Define the pitch of sound. Relate the pitch of sound to the frequency of sound waves. Identify infrasound and ultrasound.

A marching band passes you as it parades down the street. You heard it coming from several blocks away. Now that the different instruments have finally reached you, their distinctive sounds can be heard. The tiny piccolos trill their bird-like high notes, and the big tubas rumble out their booming bass notes. Clearly, some sounds are higher or lower than others.

High or LowHow high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. High-pitched sounds, like the sounds of the piccolo in theFigure below, have high-frequency waves. Low-pitched sounds, like the sounds of the

tuba Figure below, have low-frequency waves. For a video demonstration of frequency and pitch, go to this URL: http://www.youtube.com/watch?v=irqfGYD2UKw

Can You Hear It?The frequency of sound waves is measured in hertz (Hz), or the number of waves that pass a fixed point in a second. Human beings can normally hear sounds with a frequency between about 20 Hz and 20,000 Hz. Sounds with frequencies below 20 hertz are calledinfrasound. Infrasound is too low-pitched for humans to hear. Sounds with frequencies above 20,000 hertz are called ultrasound. Ultrasound is too high-pitched for humans to hear.Some other animals can hear sounds in the ultrasound range. For example, dogs can hear sounds with frequencies as high as 50,000 Hz. You may have seen special whistles that dogs—but not people—can hear. The whistles produce sounds with frequencies too high for the human ear to detect. Other animals can hear even higher-frequency sounds. Bats, like the one pictured in the Figure below, can hear sounds with frequencies higher than 100,000 Hz!

Q: Bats use ultrasound to navigate in the dark. Can you explain how?A: Bats send out ultrasound waves, which reflect back from objects ahead of them. They sense the reflected sound waves and use the information to detect objects they can’t see in the dark. This is how they avoid flying into walls and trees and also how they find flyinginsects to eat.

Summary How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of

sound waves. High-frequency sound waves produce high-pitched sounds, and low-frequency sound waves produce

low-pitched sounds. Infrasound has wave frequencies too low for humans to hear. Ultrasound has wave frequencies too

high for humans to hear.

Explore MoreAt the following URL, complete the interactive module to review and test your knowledge of the frequency and pitch of sound.http://www.engineeringinteract.org/resources/oceanodyssey/flash/concepts/pitch.htm

Review1. What is the pitch of sound?2. How is the pitch of sound related to the frequency of sound waves?3. Define infrasound and ultrasound.

Doppler EffectSounds coming from a moving source seem to change in pitch as their distance from the listener changes.

Describe the Doppler effect. Explain why the Doppler effect occurs.

Has this ever happened to you? You hear a siren from a few blocks away. The source is a police car that is racing in your direction. As the car approaches, zooms past you, and then speeds off into the distance, the sound of its siren keeps changing in pitch. First the siren gets higher in pitch, and then it suddenly gets lower. Do you know why this happens? The answer is the Doppler effect.

What Is the Doppler Effect?The Doppler effect is a change in the frequency of sound waves that occurs when the source of the sound waves is moving relative to a stationary listener. (It can also occur when the sound source is stationary and the listener is moving.) The Figure below shows how the Doppler effect occurs. The sound waves from the police car siren travel outward in all directions. Because the car is racing forward (to the left), the sound waves get bunched up in front of the car and spread out behind it. Sound waves that are closer together have a higher frequency, and sound waves that are farther apart have a lower frequency. The frequency of sound waves, in turn, determines the pitch of the sound. Sound waves with a higher frequency produce sound with a higher pitch, and sound waves with a lower frequency produce sound with a lower pitch. For an interactive animation of a diagram like the one below, go to the following URL.http://www.colorado.edu/physics/2000/applets/doppler.html

Experiencing the Doppler EffectAs the car approaches listener A, the sound waves get closer together, increasing their frequency. This listener hears the pitch of the siren get higher. As the car speeds away from listener B, the sound waves get farther apart, decreasing their frequency. This listener hears the pitch of the siren get lower. You can experience the Doppler effect with a moving siren in

the following animation: http://www.epicphysics.com/physics-animations/doppler-effect-animation/Q: What will the siren sound like to listener A after the police car passes him?A: The siren will suddenly get lower in pitch because the sound waves will be much more spread out and have a lower frequency.

Summary The Doppler effect is a change in the frequency of sound waves that occurs when the source of the

sound waves is moving relative to a stationary listener. As the source of sound waves approaches a listener, the sound waves get closer together, increasing

their frequency and the pitch of the sound. The opposite happens when the source of sound waves moves away from the listener.

Explore MoreAt the following URL, observe the Doppler effect in the animation and then answer the question. Check your answer by reading the “Discussion” section of the Web page.http://www.ndt-ed.org/EducationResources/HighSchool/Sound/dopplereffect.htm

Review1. Define the Doppler effect.2. Explain why the Doppler effect occurs.3. Does the siren of a moving police car seem to change pitch to the police officers inside the car? Why or

why not?

Hearing and the EarIllustrates the structure of the ear and how it allows us to perceive sound.

Explain how we sense sound energy and hear sounds. Identify the structures of the ear and their role in hearing.

This boy is cupping his hands behind his ears in order to hear better. Do you think this will help? To answer this question, you need to know more about sound, the ear, and how we hear.

The Sounds We HearSound is a form of energy that travels in waves through matter. The ability to sense sound energy and perceive sound is called hearing. The organ that we use to sense soundenergy is the ear. Almost all the structures in the ear are needed for this purpose. Together, they gather sound waves, amplify the waves, and change their kinetic energy to electrical signals. The electrical signals travel to the brain, which interprets them as the sounds we hear.The Figure below shows the three main parts of the ear: the outer, middle, and inner ear. It also shows the specific structures in each part of the ear. The roles of these structures in hearing are described below and in this animation:http://www.medindia.net/animation/ear_anatomy.asp.

Outer EarThe outer ear includes the pinna, ear canal, and eardrum.

The pinna is the only part of the ear that extends outward from the head. Its position and shape make it good at catching sound waves and funneling them into the ear canal.

The ear canal is a tube that carries sound waves into the ear. The sound waves travel through the air inside the ear canal to the eardrum.

The eardrum is like the head of a drum. It is a thin membrane stretched tight across the end of the ear canal. The eardrum vibrates when sound waves strike it, and it sends the vibrations on to the middle ear.

Q: How might cupping his hands behind his ears help the boy pictured in the opening image hear better?A: His hands might help the pinna of his ears catch sound waves and direct them into the ear canal.

Middle EarThe middle ear contains three tiny bones (ossicles) called the hammer, anvil, and stirrup. If you look at these bones in the Figure above, you might notice that they resemble the objects for which they are named. The three bones transmit vibrations from the eardrum to the inner ear. The arrangement of the three bones allows them to work together as alever that increases the amplitude of the waves as they pass to the inner ear.Q: Wave amplitude is the maximum distance particles of matter move when a wave passes through them. Why would amplifying the sound waves as they pass through the middle ear improve hearing?A: Amplified sound waves have more energy. This increases the intensity and loudness of the sounds, so they are easier to hear.

Inner EarThe stirrup in the middle ear passes the amplified sound waves to the inner ear through the oval window. When the oval window vibrates, it causes the cochlea to vibrate as well. The cochlea is a shell-like structure that is full of fluid and lined with nerve cells called hair cells. Each hair cell has many tiny “hairs,” as you can see in the magnified image below. When the cochlea vibrates, it causes waves in the fluid inside. The waves bend the “hairs” on the hair cells, and this triggers electrical impulses. The electrical impulses travel to the brain through nerves. Only after the nerve impulses reach the brain do we hear the sound.

Summary Sound is a form of energy that travels in waves through matter. The ear gathers and amplifies sound

waves and changes them to electrical signals. The brain receives the signals and interprets them as the sounds we hear.

The outer ear includes the pinna, ear canal, and eardrum. These structures gather sound waves, funnel them into the ear, and pass the vibrations to the middle ear.

The middle ear contains three tiny bones that amplify the vibrations as they transmit them to the inner ear.

In the inner ear, the vibrations are changed to electrical signals by hair cells lining the cochlea. The electrical signals then travel to the brain.

Explore MoreAt the following URL, review the information about the ear and hearing. Be sure to watch the hearing animation. Then fill in the blanks in the statements below.http://www.bbc.co.uk/science/humanbody/body/factfiles/hearing/hearing_animation.shtml

1. The outer ear canal ends at the __________.2. The __________ is the cavity between the eardrum and inner ear.3. The snail-like __________ is filled with fluid.4. The spiral organ of __________ consists of hair cells.5. Nerve impulses travel along the cochlear nerve to the __________.6. Because we have two ears, we are able to locate the __________ of sounds.

Review1. Summarize how we hear sounds.2. Identify the structures of the outer ear and state their functions.3. The three tiny bones of the middle ear work together as a lever. A lever is a simple machine that may

increase the force applied to it. How does this relate to the function of the middle ear?4. Loud sounds can damage the hair cells lining the cochlea of the inner ear. Explain how this might affect

the ability to hear sound.

Hearing LossWarns of the hazards loud sounds present and how to protect yourself from them.

Define deafness. Explain how loud sounds cause hearing loss. Describe how to prevent hearing loss caused by noise. Explain how hearing protectors work.

The noise of a cheering crowd at a game can be deafening! Really.

The Ear and HearingThe ear is a complex organ that senses sound energy so we can hear. Hearing is the ability to sense sound energy and perceive sound. All of the structures of the ear that are involved in hearing must work well for a person to have normal hearing. Damage to any of the structures, through illness or injury, may cause hearing loss. Total hearing loss is called deafness. To learn more about hearing loss, watch the animation at this URL:http://www.youtube.com/watch?v=YpIptQSEEjY.

Loud SoundsThe most common cause of hearing loss is exposure to loud sounds. Loud sounds can damage hair cells inside the ears. Hair cells change sound waves to electrical signals that the brain can interpret as sounds. Louder sounds, which have greater intensity than softer sounds, can damage hair cells more quickly than softer sounds. You can see the relationship between sound intensity, exposure time, and hearing loss in the followingFigure below. The intensity of sounds is measured in decibels (dB).

Q: What is the maximum amount of time you should be exposed to a sound as intense as 100 dB? What might make a sound this intense?A: You should be exposed to a 100-dB sound for no longer than 15 minutes. An example of a sound this intense is the sound of a car horn.

Shhhh!Hearing loss caused by loud sounds is permanent. However, this type of hearing loss can be prevented by protecting the ears from loud sounds. People who work in jobs that expose them to loud sounds must wear hearing protectors. Examples include construction workers who work around loud machinery for many hours each day. But anyone exposed to loud sounds for longer than the permissible exposure time should wear hearing protectors. Many home and yard chores and even recreational activities are loud enough to cause hearing

loss if people are exposed to them for too much time. You can see examples in the Figure below.

These activities expose people to dangerously loud sounds that can cause hearing loss.

How Hearing Protectors WorkYou can see two different types of hearing protectors in the Figure below. Earplugs are simple hearing protectors that just muffle sounds by partially blocking all sound wavesfrom entering the ears. This type of hearing protector is suitable for lower noise levels, such as the noise of a lawnmower or snowmobile.Electronic ear protectors work differently. They identify high-amplitude sound waves and send sound waves through them in the opposite direction. This causes destructive interference with the waves, which reduces their amplitude to zero or nearly zero. This changes even the loudest sounds to just a soft hiss. Sounds that people need to hear, such as the voices of co-workers, are not interfered with in this way and may be amplified instead so they can be heard more clearly. This type of hearing protector is recommended for higher noise levels and situations where it’s important to be able to hear lower-decibel sounds.

Summary Hearing is the ability to sense sound energy and perceive sound. The ear is the organ

that senses sound and allows us to hear. Damage to structures of the ear may cause hearing loss. Total hearing loss is called deafness.

The most common cause of hearing loss is exposure to loud sounds. Loud sounds damage hair cells in the ear that are needed for hearing. Louder sounds damage hair cells more quickly than softer sounds.

Hearing loss caused by loud sounds can be prevented by protecting the ears from loud sounds with hearing protectors. They keep sound waves out of the ears or reduce the amplitude of sound waves.

Explore MoreWatch the video about two types of hearing loss at the following URL. Then compare and contrast the two types. http://www.careflash.com/video/hearing-loss

Review1. What is hearing?2. How is deafness defined?3. How can loud sounds, like a cheering crowd at a game, contribute to hearing loss?4. Write a public service announcement explaining how and why to protect the ears from loud sounds.

Musical InstrumentsExplores how musical instruments work with examples.

Identify common features shared by all musical instruments. Describe how different categories of musical instruments make sounds and change pitch.

Do you ever see a colorful drum like this one before? It’s a traditional musical instrument of Uruguay. The drummer is equally colorful. Each time he strikes the drum, it produces a loud, pounding sound. There are hundreds of different kinds of musical instruments, from drums to horns to stringed instruments. Would it surprise you to learn that all of them make sound in the same basic way?

Making MusicPeople have been using sound to make music for thousands of years. They have invented many different kinds of musical instruments. Despite their diversity, however, musical instruments share certain similarities.

All musical instruments create sound by causing matter to vibrate. The vibrations startsound waves moving through the air.

Most musical instruments use resonance to amplify the sound waves and make the sounds louder. Resonance occurs when an object vibrates in response to sound wavesof a certain frequency. In a musical instrument such as a drum, the whole instrument and the air inside it may vibrate when the head of the drum is struck.

Most musical instruments have a way of changing the frequency of the sound waves they produce. This changes the pitch of the sounds, or how high or low the sounds seem to a listener.

Categories of Musical InstrumentsThere are three basic categories of musical instruments: percussion, wind, and stringed instruments. You can read in the Figure below how instruments in each category make sound and change pitch.

Q: Can you name other instruments in each of the three categories of musical instruments?A: Other percussion instruments include drums and cymbals. Other wind instruments include trumpets and flutes. Other stringed instruments include guitars and harps.You can learn in greater depth how musical instruments work at the following URL:http://www.bashthetrash.com/Instruments_Intro/How_Instruments_Work_-_In_Depth.html.You can learn more about specific musical instruments at these URLs:

http://www.ehow.com/video_6408523_trombone-work_.html http://www.youtube.com/watch?v=MexOZ2Z-Kwg http://www.youtube.com/watch?v=78urCu9pzi0

Summary All musical instruments create sound by causing matter to vibrate. Most musical instruments

use resonance to amplify sound waves and make sounds louder. Most musical instruments also have a way of changing the frequency of sound waves, which changes the pitch of the sounds.

There are three basic categories of musical instruments: percussion instruments such as xylophones, wind instruments such as clarinets, and stringed instruments such as violins.

Explore MoreAt the following URLs, find tips and ideas for building homemade musical instruments. Then design a musical instrument of your own. Include ways to make your instrument louder and change its pitch.

http://www.bashthetrash.com/Instruments_Intro/How_Instruments_Work_-_Easy.html http://www.nyphilkids.org/lab/main.phtml?

Review1. List three properties of most musical instruments.2. Define resonance. How is resonance used in musical instruments?3. Identify the three basic categories of musical instruments.4. What is your favorite musical instrument? In which category does it belong? How do you think it makes

sounds and changes pitch?