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10 Cards in this Set

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vibrations in the form of waves that travel through fluids (air) and are heard when they enter the ear

Fluctuations in atmospheric pressure

Wavelength and Frequency

-Wavelength: distance that a sound travels in one cycle (measured in feet or meters)

-Frequency: # of times/second a vibrating body traces one complete cycle of motion (measured in Hz) (audible range is 20-20,000 Hz)

-Low frequency = long wave lengths

-High frequency = short wave lengths


-1/10 of a bel; unit for measuring sound

-1 dB is the minimum difference that is perceptible

- 60dB + 60dB = 63dB, not 120dB

Adding dBs

-Difference in dBs 0-10: add 3,2,1, or 0 to higher dB value

- 0-1 diff. add 3 dB

- 2-3 diff. add 2 dB

- 4-9 diff. add 1 dB

- 10 or more diff. add 0

Noise Weightings (A,B,C)

- A-weighted is used by ACGIH, OSHA, and NIOSH

- A scale is most representative of human hearing.


Daily Noise Dose (DND):

90 dBA: 8hrs/day

92 dBA: 6hrs/day

95 dBA: 4hrs/day

97 dBA: 3hrs/day

100dBA: 2hrs/day

102dBA: 1.5hrs/day

105dBA: 1hrs/day

110dBA: 0.5hrs/day

115dBA: 0.25 or less hrs/day

- 5 dB increase in sound, reduce time by half

- exposure to diff. noise levels during day: C1/T1 + C2/T2 + C3/T3

Ex. 5hrs/8hrs(90dBA) + 2hrs/6hrs(92dBA) + 1hr/3hrs(97dBA)

Continuous & Impact Noise PELs

-Continuous: above 115dBA not permitted any length of time (intervals of 1 sec. or less is considered continuous)

-Impact: (hammering) do not exceed 140dBA (140dBA is considered threshold of pain)

OSHA Noise Standard PEL for 8-hour shift

-8hr PEL at 90dBA.

-8 hr TWA of 85 dBA or higher must be placed in a hearing conservation program


Health effects of noise exposure

-Noise-induced hearing loss (cumulative permanent loss of hearing, over time)

-acoustic trauma (injury to sensorineural elements of inner ear) one or few exposures to intense impact noise (happens immediately)

types of noise monitors

-Sound Level Meter: basic instrument to measure sound pressure levels. contain microphone and amplifier. range of 40-140 dB.

-Octave Band Analyzer (OBA): octave represents freq. interval between a given freq. and twice that freq. OBAs evaluate freq. of noise energy

-Noise Dosimeters: personal monitoring devices worn by workers to measure personal exposures. Records noise energy exposure during shift of worker.