Sound Study Guide Key - 2015
1. What is the definition of a wave?
A disturbance that carries energy through matter or through empty space
2. What does it mean when we say something vibrates?
It makes a small back and forth movement, very rapidly
3. How does sound energy go from the place where it starts, to the place where it is
heard?
Sound energy causes particles to vibrate, so first whatever starts the energy vibrates, and
then they hit the air particles (or water, if the thing is under water!) next to it, and they start to
vibrate, and then they hit THEIR next door neighbors and they start to vibrate, and on and on,
until the vibrations get to where they are received by an ear, or some sort of receiver.
4. Sound waves have to have matter (particles) to move. This matter through which
sound moves is called its medium.
5. What is a compression (longitudinal) wave?
A wave in which the particles vibrate parallel (or the same direction) to the direction of the
wave.
6. How can you prevent the damage caused by loud noises?
Turning down the volume on your music, using ear plugs if you HAVE to be around loud
sounds.
7. Trace the sound energy from the time the dismissal bell rings, to the time it is heard by
you.
Bell vibrates  air particles next to bell vibrate  the air particles start vibrating like dominos
falling, one after another  the air particles cause your eardrum to vibrate  the eardrum
causes the three bones (hammer, anvil and stirrup) to vibrate  the vibrations enter the
cochlea, where the hairs inside the cochlea convert the vibrations (the mechanical energy)
into electrical energy the brain interprets as sound.
8. Why can’t you see a sound wave?
Because sound waves are energy. You can’t see energy. Sound waves are a type of
mechanical energy.
9. Describe the movement of a longitudinal wave. Draw a diagram to help you explain.
The particles move in the same general direction (the same plane) as the energy, but they
don’t travel along the length of the wave. They just make little back and forth movements.
10.
Label the compressions and rarefactions on this diagram.
cmpression
wavelength
rarefaction
wavelength
11.
Label one wavelength on the picture above, and then label a second using a
different set of corresponding points.
12.
Use the graph paper below to draw a wave with a frequency of 4 Hz. Under it,
draw a wave with a frequency of 8 Hz.
13.
Define wave speed.
How fast the wave travels through the medium.
14.
Sound waves move fastest through solids. Sound waves move slowest through
gases.
15.
How does temperature affect wave speed?
The warmer the temperature the faster the particles move which increases the wave speed.
16.
What is the relationship between wavelength and frequency? (Is it direct, or
inverse?)
Wavelength is inversely related to frequency. The larger the wavelength, the lower the
frequency. The smaller the wavelength, the larger the frequency.
17.
What does the frequency of a sound wave determine?
How high or low pitched the sound is.
18.
What kind of sound do low frequency sound waves produce? High frequency
sound waves?
Low frequency waves produce low pitches; high frequency waves produce high pitches.
IMPORTANT NOTE: Hertz is the unit we use to measure the frequency of sounds. One hertz
means one wave per second.
19.
What does the amplitude of a sound wave determine?
How loud the sound is.
20.
What kind of sound does a low amplitude sound wave produce? High amplitude
sound wave?
Low amplitudes produce soft sounds; high amplitudes produce loud sounds.
IMPORTANT NOTE: Decibel is the unit we use to measure the loudness of sounds.
21.
What does it mean when we say that sound energy can be reflected? What
does it cause?
Sound energy can bounce back after hitting an object. This results in echoes.
22.
What is interference?
When waves overlap with one another.
23.
What is constructive interference? What happens when there is constructive
interference in sound waves?
When two waves overlap and the compressions and rarefactions of each are right on top of
the other. This makes the sounds louder.
24.
What is destructive interference? What happens when there is destructive
interference in sound waves?
When two waves overlap and the compressions of one are right on top of the rarefactions, so
that they are opposite of each other. This makes the sounds softer, and can sometimes even
wipe out the sound wave entirely.
25.
Name a technology that uses destructive interference.
Sound reducing headphones.
26.
What is sonar?
Technology that humans developed, because we saw bats, whales and dolphins using
echolocation. We developed machines that can send out sound waves and interpret the
reflected sound, so that we can tell where things are.
27.
What is ultrasonography?
Another technology that uses reflected sound, this is used in medicine, to help us see inside
the human body. It can be used to see unborn babies and internal organs.
Using a ultrasonography
machine, the doctors can look
at babies that haven’t been
born yet.
28.
What is resonance? Give two examples to help you remember it.
Resonance is when one object that is vibrating causes a second object to vibrate too,
because it is vibrating at its resonant frequency, or the natural frequency for the object.
Two memorable examples: opera singer breaking glass by hitting a high note, and the
Tacoma Narrows Bridge collapsing because the wind was howling at its resonant
frequency.
29.
Explain the following statement: Waves transfer energy, not matter.
The energy travels through the medium, but the medium only vibrates – it doesn’t go for the
full length of the wave.
Wave speed is affected by the medium through with the sound wave travels and also by the
temperature of the medium:
1. Name two types of animals that use reflected sound waves to help them find food, and
other animals.
Bats, whales, dolphins are three types. They use echolocation to help them find things.
You must also use the 2 sound note packets to
help prepare for the test! Using the study
guide alone is not enough.