Thursday, September 16, 2010

Terms and Definitions for Hearing Conservation

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, table, or graph showing hearing threshold level as a function of frequency.
Audiologist - A professional, specializing in the study of hearing, who is certified by the American Speech, Hearing, and Language Association of licensed by a state board of examiners.
Audiometer - An instrument for measuring the threshold or sensitivity of hearing.
Audiometry - The measurement of hearing.
Background Noise - The total of all noise in a system of situation, independent of the presence of the desired signal.
Baseline Audiogram - An audiogram obtained on testing after a prescribed period of quiet (at least 14 hours). The audiogram against which future audiograms are compared.
Bone Conduction (BC) - The process by which sound is transmitted to the inner ear through the bones of the skull.
Cochlea - A spirally wound tube, resembling a snail shell, which forms part of the inner ear and contains the end organ of hearing.
Criterion Sound Level - A sound level of 90 decibels.
Decibel - A unit for measuring the loudness of sound. One-tenth of a bel.
Dosimeter (Noise Dosimeter) - An instrument, which registers the occurrence and cumulative duration of noise exceeding a predetermined level at a chosen point in the environment or on a person.
Ear Protection - A device inserted into or placed over the ear in order to weaken air-conducted sounds.
Earmuff - A type of ear protector that encloses the entire outer ear.
Earplug - A type of ear protector that is inserted into the ear.
Frequency- The number of times per second that a sine wave repeats itself. It is expressed in Hertz (Hz).
Hair Cell - Sensory cells in the cochlea, which transform the sound, wave into a nerve impulse.
Hearing Conservation - Those measures, which are taken to reduce the risk of noise-induced hearing loss.
Hearing Loss -Impairment of auditory sensitivity.
Hearing Threshold Level- The amount by which the threshold of hearing for an ear exceeds a standard audiometric reference zero.
Hertz- Unit of measurement of frequency.
Middle Ear - A small cavity next to the ear drum.
Noise - Disturbing, harmful, or unwanted sound.
Occupational Hearing Loss - A permanent hearing loss sustained in the course of following an occupation or employment.
Organ of Corti - The end organ of hearing.
Otolaryngologist - A physician specializing in diagnosis and treatment of disorders of the ear nose and throat.
Permanent Hearing Loss- Hearing loss deemed to be irrecoverable.
Permanent Threshold Shift- That component of threshold shift which shows no progressive reduction with the passage of time when the supposed cause has been removed.
Permissible Exposure Level (PEL)- A noise exposure equivalent to an 8-hour time weighted average of 90 dBA; this represents a dose of 100 percent.
Representative Exposure- Measurements of an employee's noise dose or 8-hour time-weighted average sound level that the employer deems to be representative of the exposures of other employees in that workplace.
Temporary Threshold Shift- That component of threshold shift, which shows a progressive reduction with the passage of time after the apparent cause, has been removed.
Threshold Shift- An elevation of the threshold of hearing of an ear.
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.
Tinnitus- Ringing in the ear or noise sensed in the head.

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