These definitions apply to the following terms as used in paragraphs (c) through (n) of 29 CFR 1910.95.

Action level - An 8-hour time-weighted average of 85 decibels
 measured on the A-scale, slow response, or equivalently, a dose of
 fifty percent.
Audiogram - A chart, graph, or table resulting from an audiometric
 test showing an individual's hearing threshold levels as a
 function of frequency.
Audiologist - A professional, specializing in the study and
 rehabilitation of hearing, who is certified by the American
 Speech-Language-Hearing Association or licensed by a state board
 of examiners.
Baseline audiogram - The audiogram against which future audiograms
 are compared.
Criterion sound level - A sound level of 90 decibels.
Decibel (dB) - Unit of measurement of sound level.
Hertz (Hz) - Unit of measurement of frequency, numerically equal to
 cycles per second.
Medical pathology - A disorder or disease. For purposes of this
 regulation, a condition or disease affecting the ear, which should
 be treated by a physician specialist.
Noise dose - The ratio, expressed as a percentage, of (1) the time
 integral, over a stated time or event, of the 0.6 power of the
 measured SLOW exponential time-averaged, squared A-weighted sound
 pressure and (2) the product of the criterion duration (8 hours)
 and the 0.6 power of the squared sound pressure corresponding to
 the criterion sound level (90 dB).
Noise dosimeter - An instrument that integrates a function of sound
 pressure over a period of time in such a manner that it directly
 indicates a noise dose.
Otolaryngologist - A physician specializing in diagnosis and
 treatment of disorders of the ear, nose and throat.
Representative exposure - Measurements of an employee's noise dose
 or 8-hour time-weighted average sound level that the employers
 deem to be representative of the exposures of other employees in
 the workplace.
Sound level - Ten times the common logarithm of the ratio of the
 square of the measured A-weighted sound pressure to the square of
 the standard reference pressure of 20 micropascals. Unit: decibels
 (dB). For use with this regulation, SLOW time response, in
 accordance with ANSI S1.4-1971 (R1976), is required.
Sound level meter - An instrument for the measurement of sound
 level.
Time-weighted average sound level - That sound level, which if
 constant over an 8-hour exposure, would result in the same noise
 dose as is measured.

[39 FR 23502, June 27, 1974, as amended at 46 FR 4161, Jan. 16, 1981; 46 FR 62845, Dec. 29, 1981; 48 FR 9776, Mar. 8, 1983; 48 FR 29687, June 28, 1983; 54 FR 24333, June 7, 1989; 61 FR 5507, Feb. 13, 1996; 61 FR 9227, March 7, 1996]