Hearing Science/acoustics

Front 1

What is the difference between compression and rarefaction of a sound wave?

Back 1

Compression is the part where air molecules are very dense (compact) and rarefaction is where molecules are very sparse

Front 2

Describe a longitudinal wave

Back 2

The particle movement is parallel to the wave movement

Front 3

Describe a transverse wave

Back 3

The particle movement is perpendicular to wave direction

Front 4

Does speed of sound travel faster or slower in hot air? Why?

Back 4

Sound travels faster in warm air because warm air is less dense than cold air

Front 5

What type of wave describes propagation of sound?

Back 5

Longitudinal waves

Front 6

In which medium does sound travel the slowest? air, helium, water, or steel

Back 6

Air moves at about 1130 fps at room temperature

Front 7

Which frequencies are able to bend around corners the easiest? Describe the wavelengths of these frequencies

Back 7

Low frequencies bend the easiest because the long wavelengths allow them to bend around corners without much attenuation

Front 8

Which unit is sound power normally expressed in?

Back 8

picowatts or pW

Front 9

Which unit is sound pressure normally expressed in?

Back 9

micropascals

Front 10

Describe the difference between spherical waves and plane waves

Back 10

As spherical waves spread, intensity falls off inversely as the square of the distance (inverse square law). There is no spreading with plane waves and no intensity change with distance

Front 11

What is sound pressure at nominal threshold? Why?

Back 11

20 micropascals, which is the average sound pressure required to reach threshold at 1000 Hz for a young adult from a screened population

Front 12

What is the main reason to use a decibel scale to express the level of sound?

Back 12

Decibels compress the large range of numbers

Front 13

What decibel change is a just noticeable difference (JND)?

Back 13

3 dB

Front 14

What decibel change is a doubling of loudness?

Back 14

10 dB

Front 15

Describe difference between periodic and aperiodic waves

Back 15

A waveform that repeats itself is periodic. An aperiodic wave includes all frequencies and does not repeat itself

Front 16

To cancel a tone, a second tone must be sounded that meets which condition?

Back 16

same frequency, same amplitude, and opposite phase

Front 17

vocal fold vibration is modeled as a periodic wave with which kind of harmonics?

Back 17

Speech contains odd and even harmonics

Front 18

What is the term for the gradual decline in the amplitude of simple harmonic motion?

Back 18

damping

Front 19

what is the formula for sound pressure level in decibels?

Back 19

20 log (P/Pr)

Front 20

What is a wave which does not encounter a reflective surface?

Back 20

free progressive wave

Front 21

What is a pure tone?

Back 21

sound from a single frequency

Front 22

What kind of noise is produced by a broad band of frequencies?

Back 22

white noise

Front 23

What occurs when the driving frequency of one system matches the natural frequency of a vibrating system?

Back 23

resonance

Front 24

What type of resonance occurs when a tuning curve is tall and narrow?

Back 24

sharp resonance

Front 25

what is the beat frequency of two tones at 2024 Hz and a 2030 Hz?

Back 25

6 Hz

Front 26

What 3 characteristics describe a filter?

Back 26

center frequency, bandwidth, attenuation rate (slope)

Front 27

What attenuation (in decibels) does the inverse square law provide?

Back 27

6 dB per doubling of distance

Front 28

What term describes when sound waves bend due to a temperature inversion?

Back 28

refraction

Front 29

What term describes when sound bends around the corner of a building?

Back 29

diffraction

Front 30

The nodes on a vibrating string are points where there is what kind of motion?

Back 30

no motion

Front 31

What type of room would a free progressive wave be found?

Back 31

anechoic room

Front 32

What is it called when the distance from a source in a room where the direct sound is equal to the reverberant sound?

Back 32

critical distance

Front 33

What is the definition of reverberation time?

Back 33

The time it takes for sound to decay by 60 dB

Front 34

What component of every vibrating system causes damping to occur? What is this force named?

Back 34

Component = resistance

Force = friction

Front 35

The bandwidth of a filter is the difference between what 2 frequencies?

Back 35

The upper frequency cut-off and the lower frequency cut-off

Front 36

Describe the effects of concave and convex surface to sound

Back 36

Concave surface bends toward incident sound and focuses the sound and convex surface bends away and scatters the sound

Front 37

What type of room would a free progressive wave be found?

Back 37

anechoic room

Front 38

What is it called when the distance from a source in a room where the direct sound is equal to the reverberant sound?

Back 38

critical distance

Front 39

What is the definition of reverberation time?

Back 39

The time it takes for sound to decay by 60 dB

Front 40

What component of every vibrating system causes damping to occur? What is this force named?

Back 40

Component = resistance

Force = friction

Front 41

The bandwidth of a filter is the difference between what 2 frequencies?

Back 41

The upper frequency cut-off and the lower frequency cut-off

Front 42

Describe the effects of concave and convex surface to sound

Back 42

Concave surface bends toward incident sound and focuses the sound and convex surface bends away and scatters the sound