Washington Administrative Code › Title 296 - Labor and Industries, Department of › Chapter 296-817 - Hearing loss prevention (noise) › Section 296-817-099 - Noise definitions

Current through Register Vol. 24-14, July 15, 2024
A-weighted.
An adjustment to sound level
				measurements that reflects the sensitivity of the human ear. Used for
				evaluating continuous or average noise levels.
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,
				Hearing, and Language Association, or the American Academy of Audiology, and is
				licensed by the state board of examiners.
Baseline audiogram.
The audiogram against which
				future audiograms are compared. The baseline audiogram is collected when an
				employee is first assigned to work with noise exposure. The baseline audiogram
				may be revised if persistent standard threshold shift (STS) of improvement is
				found.
Continuous noise.
Noise with peaks spaced no more
				than one second apart. Continuous noise is measured using sound level meters
				and noise dosimeters with the slow response setting.
Criterion sound level.
A sound level of ninety
				decibels. An eight-hour exposure to constant 90 dBA noise is a one hundred
				percent noise dose exposure.
C-weighted.
An adjustment to sound level
				measurements that evenly represents frequencies within the range of human
				hearing. Used for evaluating impact or impulse noise.
Decibel (dB).
Unit of measurement of sound level.
				A-weighting, adjusting for the sensitivity of the human ear, is indicated as
				"dBA." C-weighting, an even reading across the frequencies of human hearing, is
				indicated as "dBC."
Fast response.
A setting for a sound level meter
				that will allow the meter to respond to noise events of less than one second.
				Used for evaluating impulse and impact noise levels.
Hertz (Hz).
Unit of measurement of frequency,
				numerically equal to cycles per second.
Impulsive or impact noise.
Noise levels which
				involve maxima at intervals greater than one second. Impulse and impact noise
				are measured using the fast response setting on a sound level meter.
Noise dose.
The total noise exposure received by
				an employee during their shift. It can be expressed as a percentage indicating
				the ratio of exposure received to the noise exposure received in an eight-hour
				exposure to constant noise at 90 dBA. It may also be expressed as the sound
				level that would produce the equivalent exposure during an eight-hour period
				(TWA8).
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.
Occupational hearing loss.
A reduction in the
				ability of an individual to hear either caused or contributed to by exposure in
				the work environment.
Otolaryngologist.
A physician specializing in
				diagnosis and treatment of disorders of the ear, nose, and throat.
Permanent threshold shift.
A hearing level change
				that has become persistent and is not expected to improve.
Qualified reviewer.
An audiologist,
				otolaryngologist, or other qualified physician who has experience and training
				in evaluating occupational audiograms.
Slow response.
A setting for sound level meters
				and dosimeters in which the meter does not register events of less than about
				one second. Used for evaluating continuous and average noise levels.
Sound level.
The intensity of noise as indicated
				by a sound level meter.
Sound level meter.
An instrument that measures
				sound levels.
Standard threshold shift (STS).
A hearing level
				change, relative to the baseline audiogram, of an average of 10 dB or more at
				2000, 3000, and 4000 Hz in either ear.
Temporary threshold shift.
A hearing level change
				that improves. A temporary threshold shift may occur with exposure to noise and
				hearing will return to normal within a few days. Temporary threshold shifts can
				be indicators of exposures that lead to permanent hearing loss.
TWA8 - Equivalent eight-hour
				time-weighted average sound level.
That sound level, which if constant
				over an eight-hour period, would result in the same noise dose measured in an
				environment where the noise level varies.