Costs and benefits of peak clipping in amplification for profound hearing loss.
Item
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Title
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Costs and benefits of peak clipping in amplification for profound hearing loss.
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Identifier
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AAI9959189
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identifier
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9959189
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Creator
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Iglehart, Francis Nash.
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Contributor
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Adviser: Arthur Boothroyd
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Health Sciences, Audiology
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Abstract
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Peak clipping, a common form of output limiting in hearing aids, has potential costs (distortion) and benefits (increased gain) to speech-perception ability. This study examined these costs and benefits for subjects with profound hearing loss under three conditions of clipped (by 15 dB) and unclipped speech in quiet. Phoneme-recognition ability and sensation levels were measured for 16 subjects with profound hearing loss and, for comparison, two subjects with moderate hearing loss. First, speech stimuli were clipped to 15 dB below the highest instantaneous peak value and presented at highest comfortable level. The mean phoneme-recognition score for subjects with profound losses was 18.2%. Second, speech stimuli were presented unclipped with the same instantaneous peak level as clipped speech in the first condition. The mean score for the same subjects was 13.1%. Third, unclipped speech was presented at subjects' highest comfortable level. The mean score was 17.1%. Comparisons of these scores show the benefit of increased gain available through the use of clipping and the lack of significant cost of distortion for hearing-aid users with profound losses. The benefit provided by clipping was equal to a 44% increase in channels of independent information (k = 1.44). Sensation levels were also measured. The mean level for subjects with profound hearing loss was 24.1 dB. For the two subjects with moderate hearing loss, the mean sensation level was considerably higher at 41.7 dB. Unlike the subjects with profound hearing loss, the phoneme-recognition scores for the two subjects with moderate loss were relatively unchanged across the three conditions. The relatively large sensation levels for these two subjects permitted a 15 dB attenuation of the signal without loss of phoneme recognition. Under all conditions, vowels in consonant-vowel-consonant words were more easily recognized than either initial or final consonants, and initial consonants were more easily recognized than final consonants.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
