Pure Tone AudiometryThe testing of hearing is most often carried out by establishing the threshold of hearing, the softest sound which can be perceived in a controlled environment. It is typical to do this testing with pure tones by providing calibrated tones to a person via earphones, allowing that person to increase the level until it can just be heard. Various strategies are used, but pure tone audiometry with tones starting at about 125 Hz and increasing by octaves, half-octaves, or third-octaves to about 8000 Hz is typical. Hearing tests of right and left ears are generally done independently. The results of such tests are summarized in audiograms.
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Index Hearing concepts Dangers of Loud Sounds | |||
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Audiogram Showing PresbycusisThe progressive loss of high frequency sensitivity with aging is typical, and is called presbycusis. The loss of the high frequencies can make it difficult to understand speech, since the intelligible differences in speech sounds are often in the range above 2000 Hz.
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Index Hearing concepts References Nave & Nave Ch. 18 Backus Ch. 5 | ||
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Audiograms Showing Hearing LossAudiograms can help with the diagnosis of various types of hearing disorders. Specific geometries of curves are found to be typical of presbycusis, and a characteristic notch in the hearing curve may be the signature of damage by a sudden loud sound like a gunshot or a firecracker explosion close to the ear.
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Index Hearing concepts References Nave & Nave Ch. 18 Backus Ch. 5 | ||
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