Hearing Science Test 3 Chapter 8

Front 1

In order for the inverse square law to occur, the wave must be propagated through a ___________ ___________

Back 1

free field

Front 2

As the measurement point is moved distant from the source, the intensity of the sound decrease at a rate equal to the __________ of the distance.

Back 2

square

Front 3

The small source that has the ability to pulse is known as ______________

Back 3

point source

Front 4

The point source in a free field is a sound transmitted in all directions as a _______________ wave

Back 4

spherical

Front 5

As the waves get farther from the point source they begin to _____________

Back 5

flatten out

Front 6

The energy transferred per unit time (energy/s)

Back 6

power

Front 7

As the wave begins to flatten out, what kind of wave is formed

Back 7

plane wave

Front 8

Energy per unit time per unit area (Energy/s/m^2=energy density)

Back 8

Intensity

Front 9

The decrease in intensity in a free unbound medium follows this law

Back 9

inverse square law

Front 10

the energy transferred from the source

Back 10

sound

Front 11

Compressions form a _____________, known as a wave front around the spherical point source

Back 11

spherical shell

Front 12

the wave front formed when the wave front is a considerable distance away from the point source; the radius of the sphere is very large

Back 12

Plane wave front

Front 13

If the power is constant, as the power is dissipated over a larger area as we move away from the source, the amount of energy density/intensity ____________.

Back 13

decreases

Front 14

As the measurement point is moved distant from the sound source, the intensity of the sound decreases at a rate equal to the _________ of the distance

Back 14

square

Front 15

Formula for surface area A=4πr^2

Back 15

A=4πr^2

Front 16

Each time the radius is increased by some factor, the surface area of the sphere is increased by the _________ of that factor.

Back 16

square

Front 17

If the area of the sphere increases with increasing distance from the source, the intensity must __________.

Back 17

decrease

Front 18

Energy per unit time per unit area (intensity) _____________ as power decrease because sound is dispersed over a larger area.

Back 18

decreases

Front 19

As the wavefront advances, the sound energy per unit of area _________

Back 19

diminishes

Front 20

The sound diminishes ____________ with distance from the source

Back 20

inversely

Front 21

If you increase the radius of the wave by some factor, you increase the surface area by the _________ of that factor.

Back 21

square

Front 22

If one doubles the distance, the intensity changes by a factor of ______ or about _______ dB

Back 22

4, 6

Front 23

If you double the distance, the intensity decreases by ________ the amount before the distance doubled

Back 23

1/4

Front 24

What is the formula for intensity?

Back 24

10 log D1/ (D2) ^2

Front 25

What is the formula for pressure?

Back 25

20 log the square root of [D1/(D2)^2]

Front 26

The amount of original energy that is present after sound has passed from one propagation medium through some interface to a second medium

Back 26

Transmission

Front 27

The acoustic equivalent of friction

Back 27

Absorption

Front 28

Sound energy being converted to heat is an example of __________

Back 28

Absorption

Front 29

Sound that isn't absorbed or transmitted is __________ off the surface

Back 29

Reflection

Front 30

Reflection can lead to ________ waves.

Back 30

standing

Front 31

Waves of same frequency that can be created by superpositioning

Back 31

Standing waves

Front 32

With reflection, whatever angle the incident wave hits the wall, the reflective wave will reflect from the wall at the ______ angle.

Back 32

same

Front 33

the sound wave moving from right to left toward the wall

Back 33

Incident wave

Front 34

a line perpendicular to the wave front

Back 34

ray

Front 35

Refers to the amount of the original energy that is present after sound has passed from one propagation medium through some interface to a second medium

Back 35

Transmission

Front 36

Sound that isn't absorbed or transmitted, but rather reflected off of a surface

Back 36

Reflection

Front 37

Waves of the same frequency that can be created by superpositioning

Back 37

Standing Waves

Front 38

A wave coming from the source

Back 38

Incident wave

Front 39

The angle of reflected rays (r) to the perpendicular equals the angle of the _______________ to the perpendicular

Back 39

incident rays (i)

Front 40

The type of reflection where the angle of the reflected rays to the perpendicular equals the angle of the incident rays to the perpendicular

Back 40

Reflection by plane surfaces

Front 41

What happens to the reflected waves after they hit a convex surface?

Back 41

They diverge and the sound energy scatters

Front 42

During reflection by convex surfaces intensity of the reflected sound wave at some distance from the surface will be __________ than the intensity of the incident sound wave at the same distance. (Why?)

Back 42

less (because the sound scatters)

Front 43

During reflection by concave surfaces, what happens to the rays of the reflected wave?

Back 43

They converge toward a focal point (which intensifies the reflective wave)

Front 44

The point at which the rays converge after being reflected by the concave surface of the ceiling.

Back 44

the focal point

Front 45

During reflection by concave surfaces the intensity of the reflected wave is __________ than the intensity of the incident wave

Back 45

greater

Front 46

The energy density or intensity is ________ at the focal point.

Back 46

maximal

Front 47

Reflected sound waves are called

Back 47

Echoes (Reverberating Waves)

Front 48

rooms that are designed to be without echo or reverberation

Back 48

Anechoic rooms

Front 49

The time required for a reflected wave to decay

Back 49

Reverberation time

Front 50

The reverberation time is the time required for a sound wave to be attenuated by ___ db relative to its original level

Back 50

60

Front 51

What occurs when two progressive waves (the incident & reflective waves) of the same freq and amp travel through the same medium in opposite directions?

Back 51

Standing Waves

Front 52

Positions in an enclosure where the sound seems louder or softer

Back 52

standing waves

Front 53

When two waves that are in phase meet and form a larger wave.

Back 53

Constructive Interference

Front 54

When 2 waves are partially in phase with each other meet the displacement of the resultant wave is greater than the displacement both the incident wave and the reflective wave.

Back 54

Partial Reinforcement (of amplitude)

Front 55

When two waves that are in phase with each other meet and the resultant wave is at maximal intensity, because the amplitudes of both the incident and the reflected waves are maximal. The amplitude of the resultant wave is the sum of those two waves

Back 55

Complete Reinforcement (of Amplitude)

Front 56

points of maximum displacement upward and downward

Back 56

Displacement antinodes

Front 57

In the example of the rope, the center of each loop in the rope is a ____________ _____________

Back 57

displacement antinode

Front 58

points of no vibration

Back 58

displacement nodes

Front 59

When one wave maximally reinforces the other wave because the air particles are displaced maximally & the result is a maximal increase in intensity.

Back 59

Constructive interference

Front 60

In destructive interference compressions of the incident wave are _____ degrees out of phase with compressions of the reflective wave

Back 60

180

Front 61

In destructive interference the reflective wave ___________ out the incident wave

Back 61

cancels

Front 62

In a tube that is closed on one end and open on the other, where do displacement nodes exist?

Back 62

closed end of the tube (because the air is not free to move at that location.)

Front 63

In a tube that is closed on one end and open on the other, where do displacement antinodes exist?

Back 63

Open end of the tube (where the air can move freely.)

Front 64

a point of zero pressure

Back 64

pressure node

Front 65

In a tube that is closed on one end and open on the other, where do pressure nodes exist?

Back 65

Open end of the tube

Front 66

What do pressure nodes correspond with?

Back 66

Displacement antinodes

Front 67

In a tube that is closed on one end and open on the other, where do pressure antinodes exist?

Back 67

Closed end of the tube

Front 68

What do pressure antinodes correspond with?

Back 68

Displacement nodes

Front 69

Where there is a standing wave with only one node and one antinode, a standing wave pattern is created that has a wavelength that is ______ the length of the wavelength of the incident wave

Back 69

¼

Front 70

Where there is a standing wave with only one node and one antinode, the standing wave pattern is created when the frequency of the incident sound wave has a wavelength that is ______ times the length of the tube.

Back 70

four

Front 71

Formula for the frequency of a standing wave created with one node and one antinode

Back 71

F1=s/4L

Front 72

tubes that are closed on one end and open on the other end only contain ______-integer multiples

Back 72

odd

Front 73

In tubes that are open at both ends, displacement _________ are located at each end where the air can move freely.

Back 73

antinodes

Front 74

In tubes open at both ends or closed at both ends, the frequency of the wavelength is ___x the length of the tube, creating a wavelength of the standing wave pattern that is ____ the wavelength of the incident wave.

Back 74

2, ½

Front 75

Formula for tubes open at both ends or closed at both ends

Back 75

Fn=ns/2L

Front 76

For tubes closed at both ends, a _______ is located at each end

Back 76

displacement node

Front 77

For tubes that are open at both ends/closed at both ends, if L is a fixed amount, F1 will be _____ as high in frequency as it would be for a tube that is open at only one end

Back 77

2x

Front 78

Tubes that are closed/opened at both ends will have frequencies at ___ integer multiples of F1.

Back 78

odd and even

Front 79

As length of vocal tract decreases, the frequencies of the resonances _________

Back 79

increase

Front 80

As the length of the vocal tract increases, the frequencies of the resonances _______

Back 80

decreases

Front 81

4. Resonant frequency is ___________ to the length of the vocal tract.

Back 81

inversely proportional

Front 82

Resonances also known as ________

Back 82

formants

Front 83

the bending or scattering of a sound wave around an obstacle

Back 83

diffraction

Front 84

When the wavelength of the sound wave is much larger than the size of the obstacle, diffraction is _______ efficient.

Back 84

more

Front 85

During diffraction, as wavelength increases, frequency __________

Back 85

decreases

Front 86

If the size of the barrier is large relative to the wavelength of the sound source, the energy will be
a. diffracted
b. reflected

Back 86

reflected

Front 87

If the size of the barrier is small relative to the wavelength of the sound source, some energy will be reflected back but the majority of the energy will _____________.

Back 87

diffract and converge on the other side of the barrier.

Front 88

the proportion of energy in the incident wave that is absorbed by the material of the obstacle.

Back 88

absorption coefficient

Front 89

The periodic increase and decrease of the resultant wave that results as a consequence of alternating between reinforcement and interference.

Back 89

Beats

Front 90

Rate at which grow louder or softer/ the rate at which periodic increases and decreases occur. (f2-f1)

Back 90

Beat frequency

Front 91

happens because our ears can’t distinguish between the two separate tones

Back 91

modulated sound

Front 92

Doppler Effect: As a sound source approaches you, the frequency of the sound becomes _________. As the sound source moves away, the frequency becomes ________.

Back 92

higher, lower

Front 93

When the sound source is far the wavelength is_______, there is a _______ frequency & there are _______ compressions/rarefactions

Back 93

longer, lower, fewer

Front 94

As the sound source moves toward you, the wavelength becomes _______, the frequency becomes ______, and there are ________ compressions/rarefactions.

Back 94

shorter, higher, more

Front 95

What is the formula for the doppler effect at the source is approaching you?

Back 95

f^1=f ( s/(s-s_s ))

Front 96

What is the formula for the doppler effect as the source is leaving you?

Back 96

f^1=f ( s/(s+s_s ))

Front 97

The magnitude of change is __________ to frequency and speed of moving source

Back 97

proportional