Chapter 20: Sound

Question 1

The highness or lowness of a tone related to wave frequency.

Answer 1

Pitch

Question 2

Describes a sound that has a frequency too low to be heard by the normal human ear.

Answer 2

Infrasonic

Question 3

Describes a sound that has a frequency too high to be heard by the normal human ear.

Answer 3

Ultrasonic

Question 4

Condensed region of the medium through which a longitudinal wave travels.

Answer 4

Compression

Question 5

Rarefied region (of reduced pressure) of the medium through which a longitudinal wave travels.

Answer 5

Rarefaction

Question 6

Persistence of sound, as in an echo, due to multiple reflections.

Answer 6

Reverberation

Question 7

Bending of sound or any wave caused by a difference in wave speeds.

Answer 7

Refraction

Question 8

The setting up of vibrations in an object by a vibrating force.

Answer 8

Forced vibration

Question 9

A frequency at which an elastic object naturally tends to vibrate if it is disturbed and the disturbing force is removed.

Answer 9

Natural frequency

Question 10

The response of a body when a forcing frequency matches its natural frequency.

Answer 10

Resonance

Question 11

A result of superposing different waves, often of the same wavelength.

Answer 11

Interference;

Constructive interference results from crest-to-crest reinforcement; destructive interference results from crest-to-trough cancellation.

Question 12

A series of alternate reinforcements and cancellations produced by the interference of two waves of slightly different frequencies, heard as a throbbing effect in sound waves.

Answer 12

Beats

Question 13

The approximate range of human hearing is

Answer 13

20 hertz to 20,000 hertz

Question 14

Compressions and rarefactions are characteristic of

Answer 14

longitudinal waves

Question 15

The speed of a sound wave in air depends on: a) its frequency; b) its wavelength; c) the air temperature; d) All of the above

Answer 15

c) the air temperature

Question 16

A dolphin perceives its environment by the sense of: a) sight; b) sound; c) both sight and sound; d) neither sight nor sound

Answer 16

c) both sight and sound

Question 17

For FM radio, the F stands for

Answer 17

frequency

Question 18

A sound wave is a

Answer 18

longitudinal wave

Question 19

A sound source of high frequency has high

Answer 19

pitch

Question 20

Sound travels fastest in: a) air; b) water; c) steel; d) a vacuum; e) Sound travels at about the same speed in all of the above media

Answer 20

c) steel

Question 21

The explanation for refraction must involve a change in

Answer 21

speed

Question 22

The natural frequency of an object depends on its

Answer 22

size, shape, and elasticity

Question 23

The frequencies of sound that carry farther in air are

Answer 23

low

Question 24

You watch a person chopping wood and note that after the last chop you hear it 1 second later. How far away is the chopper: a) 340 m; b) more than 340 m; c) less than 340 m; d) There’s no way to tell;

Answer 24

a) 340 m;

Question 25

You hear thunder 2 seconds after you see a lighting flash. How far away is the lightning: a) 340 m/s; b) 680 m/s; c) less than 340 m/s; d)There’s no way to tell;

Answer 25

b) 680 m/s;

Question 26

Reverberations are best heard when you sing in a room with: a) carpeted walls; b) hard-surfaced walls; c) open windows; d) none of the above;

Answer 26

b) hard-surfaced walls;

Rigid walls better reflect sound energy. Fabric is absorbent, and open windows let sound energy escape from the room.

Question 27

When air near the ground on a warm day is warmed more than the air above, sound tends to bend: a) upward; b) downward; c) at right angles to the ground; d) none of the above;

Answer 27

a) upward;

Question 28

Interference is a property of: a) sound; b) light; c) both a and b; d) neither a nor b;

Answer 28

c) both a and b;