Mountain Time USA
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GLOSSARY OF TERMS
RELEVANT TO HEARING CONSERVATION PROGRAMS
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.