Physical Science Module 14

Front 1

What determines how loud a sound is?

Back 1

The amplitude of a sound wave. Low amplitude waves are quiet, and high amplitude waves are loud. Amplitude does not affect pitch.

Front 2

crest

Back 2

the high point of a wave

Front 3

trough

Back 3

the low point of a wave

Front 4

wavelength

Back 4

the distance in meters between 2 crests of a wave.

Front 5

frequency

Back 5

The number of waves that pass a reference point in 1 second.

Front 6

formula for frequency

Back 6

wave speed divided by wavelength.

Front 7

How are frequency and wavelength related to each other?

Back 7

The longer the wavelength, the smaller the frequency. The shorter the wavelength, the higher the frequency.
They are inversely proportional to each other.

Front 8

Hertz

Back 8

The units for frequency. 1/second.

Front 9

transverse wave

Back 9

A wave in which the direction of propagation is perpendicular to the direction of oscillation. Like an ocean wave.

Front 10

longitudinal wave

Back 10

A wave with a direction of propagation parallel to the direction of oscillation.

Front 11

What type of wave is sound?

Back 11

longitudinal

Front 12

What is sound actually?

Back 12

It is compression of the atoms of the medium (air/water/etc.) in which the sound is traveling.

Front 13

Is there sound in a vacuum?

Back 13

No. Without a medium to compress, there can be no sound.

Front 14

What do the crests in a transverse wave correspond to in a longitudinal wave?

Back 14

The crests are like the compressions in a longitudinal wave, when the atoms in the medium are smashed closer together than usual.

Front 15

What do the troughs in a transverse wave correspond to in a longitudinal wave?

Back 15

They are like the rarefactions in a longitudinal wave, where the atoms in the medium are spread out more than usual from each other.

Front 16

Name two things on which the speed of sound is dependent.

Back 16

1. The type of medium in which it is transmitted.

2. The temperature of the medium.

Front 17

How is the speed of sound calculated in air?

Back 17

v=(331.5+0.6T)m/sec.

T is the temperature in Celcius.

Front 18

How does the speed of sound vary depending on the medium?

Back 18

Sound travels fastest in solids, then, liquids, and slowest in gases.

Front 19

supersonic speed

Back 19

Any speed that is faster than the speed of sound in the substance of interest.

Front 20

sonic boom

Back 20

The sound produced as a result of an object traveling at or above Mach 1.

Front 21

pitch

Back 21

An indication of how high or low a sound is, which is primarily determined by the frequency of the sound wave.

Front 22

How are pitch and frequency related?

Back 22

Sound waves with low pitch have low frequency.
Sound waves with high pitch have high frequency.

Front 23

How are pitch and wavelength related?

Back 23

Sound waves with low pitch have long (large) wavelengths.
Sound waves with high pitch have short (small) wavelengths.

Front 24

What is the frequency range for sonic waves?

Back 24

20 Hz through 20,000 Hz. This is the range humans can typically hear.

Front 25

ultrasonic waves

Back 25

Waves with frequencies over 20,000 Hz, such as those used in medical ultrasounds.

Front 26

In simplified terms, how does the human ear work?

Back 26

Sound waves hit the tympanic membrane, which starts to vibrate according to the wavelength of the sound. These vibrations are passed on to the cochlea, which translates the vibrations to electrical impulses which are sent to the brain and interpreted as a particular sound.

Front 27

infrasonic waves

Back 27

Waves with frequencies under 20 Hz.

Front 28

Doppler Effect

Back 28

The motion-induced change in the observed frequency (and therefore pitch) of a wave.

Front 29

Why is the pitch of a car horn higher when it is moving toward you than when it is passing you?

Back 29

Because the car, which is emitting the sound, is moving toward you, the sound waves in front of the car get bunched up, making the frequency higher to someone in front of the car than the actual frequency of the car horn.

Front 30

Why is the pitch of a car horn lower when it is moving away from you than the true pitch of the horn?

Back 30

When the car (the source of the sound waves) is moving away from you, the waves behind it are spread apart further, making the pitch sound lower.

Front 31

How is a sonic boom generated?

Back 31

The airplane is constantly generating pressure waves in the air (sound). Some of these wave move forward, in front of the plane. As the plane increases speed (and continues to make sound waves), the waves begin to be closer and closer together, since the source that is generating them, the plane, is starting to move just as fast as the waves. These waves add to each other, and make a very large shock wave. When the plane goes faster than Mach 1, the waves spread out in a cone behind the plane (none can go in front because the plane is moving faster than sound).

Front 32

How can loud noises damage the cochlea?

Back 32

The larger the amplitude of the wave, the more the tympanic membrane vibrates. The more the TM vibrates, the more potential damage to the cochlea cells, which cannot be regenerated once they die.

Front 33

If 2 sounds are made, and one is 100 times louder than the other, how does it sound to our brains?

Back 33

The louder sound is regulated down by the cochlea, which then sends the dampened signal to our brain. Therefore, the louder sound will seem louder, but not 100 times louder. By dampening its response, the cochlea is able to respond over a much greater range of sound (a range of 10 trillion times from the softest sound we can hear up to a sound that could damage hearing.) We aren't aware of the incredible range because the cochlea brings it into a much smaller perceived range by dampening the louder sounds.

Front 34

What is the bel scale?

Back 34

The bel scale measures the intensity of a sound wave (a measure of its amplitude.) We tend to measure sounds in decibels, which are tenths of bels. We hear sounds from 0 decibels to 130 decibels (damage.)

Front 35

What is an echo and how is it produced?

Back 35

An echo is a reflected sound wave, produced when there is a change in the medium in which sound travels. When a wave goes from air to a cliff wall, for example, some of the sound wave enters the wall and some bounces back off the wall toward its source. If the reflected sound reaches your ear at least 0.1 seconds after it was originally made, your ear perceives it as a different sound, or echo. This corresponds to a distance of over 100 feet away.