Compliance Guide to MSHA's
Access. The right to examine and copy records.
Action level. An 8-hour time-weighted average sound level (TWA8) of 85 dBA, or equivalently a dose of 50%, integrating all sound levels from 80 dBA to at least 130 dBA.
Audiologist. A professional, specializing in the study and rehabilitation of hearing, who is certified by the American Speech-Language-Hearing Association (ASHA) or licensed by a state board of examiners.
Baseline audiogram. The audiogram recorded in accordance with Section 62.170 of this part against which subsequent audiograms are compared to determine the extent of hearing loss, except in those specific situations in which this part requires the use of a revised baseline audiogram for such a purpose.
Criterion level. The sound level which, if applied for 8 hours, results in a dose of 100% of that permitted by the standard.
Decibel (dB). A unit of measure of sound pressure levels, defined in one of two ways, depending upon the use:
Exchange rate. The amount of increase in sound level, in decibels, which would require halving of the allowable exposure time to maintain the same noise dose. For the purposes of this part, the exchange rate is 5 decibels (5 dB).
Hearing protector. Any device or material, capable of being worn on the head or in the ear canal, sold wholly or in part on the basis of its ability to reduce the level of sound entering the ear, and which has a scientifically accepted indicator of noise reduction value.
Hertz (Hz). Unit of frequency numerically equal to cycles per second.
Medical pathology. A condition or disease affecting the ear.
Miner's designee. Any individual or organization to whom a miner gives written authorization to exercise the miner's right of access to records.
Permissible exposure level. A TWA8 of 90 dBA, or equivalently, a dose of 100% of that permitted by the standard, integrating all sound levels from 90 dBA to at least 140 dBA.
Qualified technician. A technician who has been certified by the Council for Accreditation in Occupational Hearing Conservation (CAOHC), or by another recognized organization offering equivalent certification.
Reportable hearing loss. A change in hearing sensitivity for the worse, relative to the miner's baseline audiogram or, in the case of a revised baseline audiogram where one has been established in accordance with § 62.170(c)(2), relative to such revised baseline audiogram, of an average of 25 dB or more at 2000, 3000, and 4000 Hz in either ear.
Revised baseline audiogram. An annual audiogram designated, as a result of the circumstances set forth in § 62.170(c)(1) or § 62.170(c)(2) of this part, to be utilized in lieu of a miner's original baseline audiogram in measuring changes in hearing sensitivity.
Sound level. For purposes of this part, the sound pressure level in decibels measured using the A-weighting network and a slow response, expressed in the unit dBA.
Standard threshold shift. A change in hearing sensitivity for the worse relative to the miner's baseline audiogram, or relative to the most recent revised baseline audiogram where one has been established, of an average of 10 dB or more at 2000, 3000, and 4000 Hz in either ear.
Time-weighted average - 8 hour (TWA8). The sound level which, if constant over 8 hours, would result in the same noise dose as is measured.