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PHA BLK 5 > Physics of Sound > Flashcards

Physics of Sound Flashcards

1
Q

sensation that results from the stimulation of the auditory mechanism by pressure variations in any “elastic” medium

A

sound

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2
Q

unwanted sound

A

noise

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3
Q

requirements for sound

A

1st- sender
2nd- medium
3rd- receiver

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4
Q

source of vibration and source of energy

A

sender

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5
Q

carries the pressure change

A

medium

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6
Q

auditory mechanism to receiver and interpret the signal

A

receiver

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7
Q

causes alternative pressure changes in the air molecules

A

vibration

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8
Q

molecules of the medium forced together causing high pressure

A

compression

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9
Q

molecules of the medium separate causing low pressure

A

rarefaction

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10
Q

a series of compression + rarefactions

A

sound wave

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11
Q

what does speed depend on

A

depends on the medium, the denser the medium, the faster sound travels

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12
Q

1,100 feet per second

A

air

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13
Q

4,500 feet per second

A

water

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14
Q

15,000 feet per second

A

steel

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15
Q

graphical representation of the compressions and rarefactions

A

sine wave

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16
Q

horizontal axis

A

time

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17
Q

vertical axis

A

molecular vibrations

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18
Q

frequency is also known as

A

pitch

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19
Q

sound frequency is quantified in terms of

A

hertz (Hz)

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20
Q

human ear is sensitive to frequencies as low as ___Hz and as high as ___Hz

A

20
20,000

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21
Q

speech hearing range

A

250 Hz - 4000 Hz

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22
Q

consonant sounds

A

high frequencies

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23
Q

vowel sounds

A

low frequencies

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24
Q

human ear is MOST sensitive to sounds in the range between ___Hz and ___Hz

A

1000
4000

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25
Q

human ear is LEAST sensitive in

A

low frequency range

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26
Q

what determines intensity or loudness of a sound

A

pressure or energy exerted at the source of the sound

27
Q

human ear’s perception of amplitude

A

loudness

28
Q

intensity is expressed in

A

decibels (dB)

29
Q

range intensity range for human ears

A

0-140 dB

30
Q

represents the average we can hear

A

0 dB

31
Q

where serious and immediate damage can occur

A

140 dB

32
Q

background noise begins to interfere with communication

A

50 dB

33
Q

level of average speaking voice

A

60 dB

34
Q

hazardous continuous noise

A

80 dB

35
Q

hazardous impact noise

A

140 dB

36
Q

possible tissue damage

A

170-180 dB

37
Q

possible death

A

180+ dB

38
Q

if you need to shout to be understood from 3ft away, you are in a potentially hazardous noise environment

A

three foot rule

39
Q

last longer than one second

A

continuous noise

40
Q

large differences in sound level occur during the day, with periodic interruptions of relative quiet periods

A

intermittent noise

41
Q

noise levels that vary in intensity with no significant quiet periods

A

varying noise

42
Q

very short burst of noise lasting less than one second

A

impulse noise

43
Q

noises are slightly longer in duration than impulse noises

A

impact

44
Q

combination of sound waves with a mix of frequencies, with varying intensities

A

complex tones

45
Q

simplest form of sound and represents one frequency

A

pure tone

46
Q

microphone to measure sound pressure level (SPL)

A

sound level meter (SLM)

47
Q

is the amount of sounder energy in the atmosphere

A

sound pressure level (SPL)

48
Q

the decibel scale is

A

logarithmic

49
Q

scale used by BE
mimicking of the human ear

A

dBA SPL
A scale

50
Q

captures more of the low frequency sounds and slightly more of the high frequency sounds than the A-weighting filter

A

dBC SPL
C scale

51
Q

very loud, fast sounds (impulse noise)

A

dBP SPL
P scale

52
Q

hearing test derived by testing a large group of young, normal hearing people
comparing frequencies over time

A

HTL scale

53
Q

when a noise source is doubled the noise level will

A

increase by 3 dB
example: two machines running at 90dB, overall sound level is 93dB

54
Q

doubling the distance from a sound source the intensity of the exposure will
inverse square law

A

decrease by 6dB

55
Q

when ___ are used, high frequency sounds are attenuated more than low frequencies

A

barriers

56
Q

amount of time a worker is exposed to hazardous noise over the work day (8-hr day)

A

time-weighted average (TWA)

57
Q

percentage of an allowable noise exposure the worker experiences through the work day.

A

noise dose

58
Q

noise dose takes into account two factors:

A

permissible exposure limit (PEL)
exchange rate

59
Q

8 hour time-weighted average exposure at which point 100% noise dose is reached

A

permissible exposure limit (PEL)

60
Q

OSHA and most U.S. government regulations use ___dBA as the PEL standard

A

90

61
Q

DoD sets the maximum PEL at ___dBA

A

85

62
Q

the amount of decibel increase/decrease in the TWA noise exposure causes the noise dose to double (or cut in half)

A

decibel exchange rate

63
Q

when the steady sound level is increased, what happens to the duration

A

cuts in half
examples: 85 dBA increased to 88dBA the duration goes from 8 hrs to 4 hrs

PHA BLK 5 (11 decks)

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