Audiometry

(redirected from Pure tone audiometry)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Pure tone audiometry: impedance audiometry, speech audiometry

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

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

audiometry

[‚ȯd·ē′äm·ə·trē]
(acoustics)
The study of hearing ability by means of audiometers.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Key Words: Hearing loss, Pure tone audiometry, Hearing protection devices, Ear Muffs, Ear Plugs
A hearing test was done by conventional pure tone audiometry in a soundproof booth by two audiologists from the Department of Clinical Physiology.
Where someone was unable to understand the pure tone audiometry test explanations, I used a basic whisper voice test to ascertain a basic level of hearing.
Pure tone audiometry examination results at frequencies ranging from 0.5 to 8 kHz showed that the frequency of hearing loss among cauliflower ears was higher than this rate among non-cauliflower ears.
The assessment of hearing is primarily a subjective test and no test other than a properly conducted pure tone audiometry test (carried out under ideal conditions) can tell us the exact hearing threshold level of the patient.
Pure Tone Audiometry. Pure tone audiometry, including air conduction thresholds at 0.125-8 kHz and bone conduction thresholds at 0.5-4 kHz, was performed using a GN Resound Orbiter 922 version 2 audiometer, according to ISO 8253-1 [13], using Telephonics TDH-39 earphones and a Radio Ear B71 bone conductor in a sound-attenuating booth complying with standards specified in ISO 8253-2 [14].
Pure tone audiometry was also conducted during the time period of the field sampling with a total of 207 consenting questionnaire respondents (40.2% of 511), from either the Agbowo (n = 122, or 40.1% of 304) and Ajibode (n = 85, or 40.3% of 211) business districts.
Patients underwent pure tone audiometry (PTA) and tympanometry on admission, then monthly for 3 months.
All patients diagnosed as having hearing loss, using pure tone audiometry threshold measurement were assessed for associated symptoms apart from the hearing loss.
Hearing assessment was done by general ear examination and Pure Tone Audiometry so as to determine hearing function, the degree, type and configuration of a hearing loss if any.
Pure tone audiometry is the key hearing test used to identify hearing threshold levels of an individual, enabling determination of the degree, type and configuration of a hearing loss.
He presents 17 chapters covering acoustics and sound measurement, anatomy and physiology of the auditory system, measurement principles and the nature of hearing, the audiometer and test environment, pure tone audiometry, auditory system and related disorders, acoustic immittance assessment, speech audiometry, clinical masking, behavioral tests for audiological diagnosis, physiological methods in audiology, assessment of infants and children, audiological screening, nonorganic hearing loss, audiological management, and effects of noise and hearing conservation.