Masking overshoot: Effects of ipsilateral, bilateral and contralateral priming.
Item
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Title
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Masking overshoot: Effects of ipsilateral, bilateral and contralateral priming.
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Identifier
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AAI9908304
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identifier
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9908304
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Creator
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Connington, Maureen Catherine.
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Contributor
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Adviser: Arthur Boothroyd
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Date
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1998
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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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Physics, Acoustics | Health Sciences, Audiology | Psychology, Physiological
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Abstract
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This study was concerned with masking overshoot, the elevation of the threshold of a brief signal when it is presented at the onset of a masking noise rather than at its temporal center. More specifically, it was concerned with the release from overshoot (i.e., threshold improvement) produced by priming stimuli, presented ipsilaterally, bilaterally and contralaterally at primer-masker gaps of 20, 40 and 80 msec. The more general purpose of the study was to assess the contributions of peripheral and central factors to the overshoot and overshoot-release phenomena.;The primers and masking stimuli consisted of white noise bursts of 200 and 400 msec duration, respectively. The probe signal was a 20 msec 4kHz tone. The tone and masker were always presented in one ear. There were, however, 3 modes of primer presentation: ipsilateral, bilateral (identical waveforms to both ears) and contralateral. Three primer-masker gaps of 20, 40 and 80 msec were used. Five normally hearing adults were tested at primer and masker levels of 80 dB HL.;Four of the five subjects exhibited significant masking overshoot, when tested without priming. Ipsilateral priming with 20 and 40 msec gaps produced significant masking release from overshoot. Threshold became poorer, however with increasing gap duration and with increasing distance of the perceived primer from the test ear (i.e. ipsilateral priming produced better thresholds than did bilateral priming and bilateral priming produced better thresholds than contralateral priming). There was significant masking enhancement (i.e. threshold was significantly poorer than in the unprimed probe at onset condition) with the contralateral 80 msec primer. The fact that ipsilateral and bilateral primers performed differently does not support the theory that masking overshoot and its release are solely the results of peripheral adaptation. In fact, the group results support the conclusion that masking overshoot is influenced by central factors. However, there were marked inter-subject differences. It seems possible that masking overshoot and its release are influenced by both peripheral adaptation effects and central processes and that the balance between the two is subject-dependent.
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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.
