Audiometry

(redirected from audiometers)
Also found in: Dictionary, Thesaurus, Medical.

Audiometry

The quantitative assessment of individual hearing, either normal or defective. Three types of audiometric tests are used: pure tone, speech, and bone conduction tests. Such tests may serve various purposes, such as investigation of auditory fatigue under noise conditions, human engineering study of hearing aids and communication devices, screening of individuals with defective hearing, and diagnosis and treatment of defective hearing. In all of these situations, individual hearing is measured relative to defined standards of normal hearing.

The pure-tone audiometer is the instrument used most widely in individual hearing measurement. It is composed of an oscillator, an amplifier, and an attenuator to control sound intensity. For speech tests of hearing, word lists called articulation tests are reproduced on records or tape recorders. Measurements of detectability or intelligibility can be made by adjusting the intensity of the test words. To make bone conduction tests, sound vibrations from the audiometer activate a vibrator located on the forehead or mastoid bone.

Scientific advance in audiometry demands careful control of all environmental sound. Two types of rooms especially constructed for research and measurement of hearing are the random diffusion, or reverberation, chamber and the anechoic room. In the reverberation chamber, sounds are randomly reflected from heavy nonparallel walls, floor, and ceiling surfaces. In the anechoic room, the fiber glass wedges absorb all but a small percent of the sound.

The measurement of hearing loss for pure tones in defective hearing is represented by the audiogram (see illustration). Sounds of different frequencies are presented separately to each ear of the individual, and the intensity levels of the absolute thresholds for each frequency are determined. The absolute threshold is the lowest intensity which can be detected by the individual who is being tested.

Audiogram for determining the audibility curve for pure-tone hearing loss at various frequency levelsenlarge picture
Audiogram for determining the audibility curve for pure-tone hearing loss at various frequency levels

In clinical audiometry the status of hearing is expressed in terms of hearing loss at each of the different frequency levels. In the audiogram the normal audibility curve, representing absolute thresholds at all frequencies for the normal ear, is represented as a straight line of zero decibels. Amount of hearing loss is then designated as a decibel value below normal audibility. The audiogram in the illustration reveals a hearing loss for tones above 500 Hz. Automatic audiometers are now in use which enable individuals to plot an audiogram for themselves.

Articulation tests are speech perception or speech hearing tests used to assess hearing and loss of hearing for speech. The threshold of intelligibility for speech is defined as the intensity level at which 50% of the words, nonsense syllables, or sentences used in the articulation test are correctly identified. The hearing loss for speech is determined by computing the difference in decibels between the individual intelligibility threshold and the normal threshold for that particular speech test. Discrimination loss for speech represents the difference between the maximum articulation score at a high intensity level (100 dB), expressed in percent of units identified, and a score of 100%. The measure of discrimination loss is important in distinguishing between conduction loss and nerve deafness.

Bone conduction audiograms are compared with air conduction audiograms in order to analyze the nature of deafness. Losses in bone conduction hearing generally give evidence of nerve deafness, as contrasted to middle-ear or conduction deafness. See Ear (vertebrate), Hearing impairment

Audiometry

 

acoumetry, measurement of the acuteness of hearing. Since acuteness of hearing is defined generally by the threshold of perception of a sound, audiology consists in the determination of the weakest sound perceived by man. The simplest audiometric methods are the detection of the perception of sounds of various volumes produced by human speech and by tuning forks of varying lengths. In general, audiometry is performed by special electrical acoustic devices—audiometers. For a change in pitch (from 100 to 8,000 cycles per second) and volume of sound (from 0 to 125 decibels) on the audiometer, the minimum intensity for which the sound is still barely audible (threshold of perception) is ascertained. The results of audiometry are recorded in the form of an audiogram—a curve drawn on a special audiometric grid. By determining the patient’s threshold intensity of sound on a scale, the degree of hearing loss is determined. Audiometers are also used in other, more complicated tests.

L. V. NEIMAN

audiometry

[‚ȯd·ē′äm·ə·trē]
(acoustics)
The study of hearing ability by means of audiometers.
References in periodicals archive ?
Calibration of audiometer and requirements for test booths
This data can include hearing and pulmonary tests, which actually can be brought over automatically from an audiometer or spirometer.
For more information on the MADSEN Astera audiometer, visit www.
Table 32: World Recent Past, Current & Future Analysis for Measurement/Testing Devices by Product Segment - Otoscopes, Audiometers, Impedance Analyzers, Hearing Aid Analyzers and Others Markets Independently Analyzed with Annual Sales Figures in US$ Million for Years 2000 through 2010 (includes corresponding Graph/Chart) II-86
Table 33: World Long-term Projections for Measurement/ Testing Devices by Product Segment - Otoscopes, Audiometers, Impedance Analyzers, Hearing Aid Analyzers and Others Markets Independently Analyzed with Annual Sales Figures in US$ Million for Years 2011 through 2015 (includes corresponding Graph/Chart) II-86
Table 34: World 10-Year Perspective for Measurement/Testing Devices by Product Segment - Percentage Breakdown of Dollar Sales for Otoscopes, Audiometers, Impedance Analyzers, Hearing Aid Analyzers and Others Markets for 2003, 2008 & 2012 (includes corresponding Graph/Chart) II-87
Jasna 1, account number 95 1240 6247 1111 0000 4975 9963 with the note "bid bond to tender for the supply of audiometers - Part .
The increase in net sales is a result of the company continuing to aggressively market its Pilot Audiometer, introduced last fiscal year, in addition to its current tympanometry product line.
The 160 percent increase in net sales is a result of the company's aggressive marketing efforts for its Pilot Audiometer, along with its current line of tympanometry products.
The overall increase in profits in 1995 was primarily the result of a 24 percent increase in net sales along with a more favorable sales mix due to the successful introduction of the new Pilot Audiometer.
Delivery of new diagnostic tools for visual conditional audiometry for stem auditory potentials (BERA) and brain auditory evoked potentials (CAEP), to verify the correct target profit of hearing (electroacoustic verification) and 1 clinical audiometer, including all accessories.
repair equipment model stadler audiometer gsi 61 grason: change wires left and right airway grason stadler brand codes 4204-0160 and 4204-0161 replacement parts required, must also bidders brand representatives be