Frequency specificity of the auditory brainstem and the middle latency responses.
Item
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Title
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Frequency specificity of the auditory brainstem and the middle latency responses.
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Identifier
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AAI9618088
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identifier
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9618088
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Creator
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Oates, Margaret Ann.
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Contributor
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Adviser: David R. Stapells
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Date
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1996
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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 | Biology, Neuroscience
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Abstract
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This dissertation examined three controversial issues with respect to the frequency specificity of the auditory brainstem (ABR) and middle latency (MLR) responses to brief tonal stimuli: (1) the use of low-frequency stimuli (i.e., 500 Hz) at high stimulus intensities for recording the ABR; (2) the suggestion that the MLR provides a more frequency-specific response to low-frequency tones compared to the ABR; and (3) the use of a nonlinear-gated stimuli (e.g., exact-Blackman-gated tone) versus conventional linear-gated stimuli to improve the frequency specificity of the ABR and/or MLR.;The frequency specificity of the ABR and MLR to 500- and 2000-Hz brief tones was investigated in 12 normal subjects using the high-pass noise/derived response technique (1/2-octave- and 1-octave-wide derived bands). Stimuli were exact-Blackman-(5 cycles) and linear-(2-1-2 cycles) gated tones presented at 80 dB peak-to-peak equivalent (ppe) SPL. Cochlear contributions to ABR wave V-V{dollar}\sp\prime{dollar} and MLR wave Na-Pa were assessed by: (1) effects of high-pass noise masking on response amplitudes and latencies; and (2) response amplitude profiles as a function of derived-band center frequency.;The high-pass noise and derived response results indicate that the ABR and MLR to 80 dB ppe SPL brief tones show good frequency specificity. The maxima in the ABR and MLR amplitude profiles occurred in the 500- and 707-Hz derived bands for the exact-Blackman- and linear-gated 500-Hz tones. The peak in the ABR amplitude profiles to both 2000-Hz stimuli was seen in the 2000-Hz derived band. For the MLR, the largest peaks in the amplitude profiles occurred in the 2000-and 1410-Hz derived bands for the exact-Blackman- and linear-gated tones. Cochlear contributions to the ABR and MLR to these tones were also present but smaller at 0.5 to 1 octave above and below the nominal frequencies of the stimuli. To summarize, ABRs and MLRs to 80 dB ppe SPL 500- and 2000-Hz brief tones show good frequency specificity and no significant differences were found in the frequency specificity of: (1) ABR versus MLR; (2) responses to 500-versus 2000-Hz tones; and (3) responses to exact-Blackman- versus linear-gated tones.
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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.
