| hearing aid | An electronic amplifying device designed to bring sound more effectively into the ear; it consists of a microphone, amplifier, and receiver. (05 Mar 2000) |
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| hearing aids | Devices which amplify sound to help persons with hearing loss. (12 Dec 1998) |
| hearing impaired persons | Persons with any degree of loss of hearing that has an impact on their activities of daily living or that requires special assistance or intervention. (12 Dec 1998) |
| hearing impairment | Hearing loss A reduction in the ability to perceive sound; may range from slight to complete deafness. See: deafness, threshold shift. (05 Mar 2000) |
| hearing level | The measure of the status of hearing as read directly on the hearing loss scale of an audiometer; described in decibels as a deviation from a standard value for zero on the audiometer. (05 Mar 2000) |
| Helmholtz theory of hearing | That the basilar membrane of the cochlea acts as a resonating structure, recording low tones from its apical turns and high tones from its basal turns. Synonym: Helmholtz theory of hearing. (05 Mar 2000) |
| normal hearing | The ability to perceive sound normally. Synonym: normal hearing. Origin: G. Akousis, hearing (05 Mar 2000) |
| organ of hearing | The content of the cochlea including the portion of the membranous labyrinth containing the spiral organ (cochlear duct) and the perilymphatic channels (scalae) which lie on either side. Synonym: labyrinthus cochlearis, organ of hearing. (05 Mar 2000) |
| accidents, occupational | Unforeseen occurrences, especially of an injurious character due to factors involving one's employment. (12 Dec 1998) |
| air pollutants, occupational | Air pollutants found in the work area. They are usually produced by the specific nature of the occupation. (12 Dec 1998) |
| national institute for occupational safety and health | An institute of the centres for disease control and prevention which is responsible for assuring safe and healthful working conditions and for developing standards of safety and health. Research activities are carried out pertinent to these goals. (12 Dec 1998) |
| noise, occupational | Noise present in occupational, industrial, and factory situations. (12 Dec 1998) |
| dermatitis, occupational | A recurrent contact dermatitis caused by substances found in the work place. (12 Dec 1998) |
| injuries, poisonings, and occupational diseases | Disorders representing collectively the results of assault by external forces, rather than by organic or physiologic dysfunction or by pathogens. (12 Dec 1998) |
| occupational deafness | Sensorineural hearing loss due to overexposure to high intensity noise levels. Synonym: boilermaker's deafness, industrial deafness, occupational deafness. (05 Mar 2000) |