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BGSU_Dissertations_0645_Rizzo.pdf (1.4 MB)

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Effects of Backward Masking on Human Auditory Brainstem Responses

Rizzo, Stephen Richard, Jr.
http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1570783750515013

Abstract Details

1980, Doctor of Philosophy (Ph.D.), Bowling Green State University, Communication Studies.
The purpose of this study was to determine whether backward masking (BWM) is mediated in the brainstem of the human central auditory nervous system (CANS).Separate experiments were conducted for the psychophysical and electrophysiological conditions. The psychophysical experiment established the BWM threshold shift functions between the click only (CO) and the click masker (CM) conditions. Four subjects determined their BWM thresholds at t's of -1, -5, -10, -25, and -100 msec and at masker levels of 50, 65, and 80 dB SPL. For each subject, more BWM was observed at short t’s (-10 to -1 msec) than at long t’s (-100 to -10 msec). As the intensity of the masker increased there was an increase in the amount of BWM. This was true for t’s less than -10 msec. For longer intervals, the effect of masker level on threshold shift was smaller. The electrophysiological experiment consisted of collecting auditory brainstem responses (ABR) to the same experimental conditions used in the psychophysical experiment. The intensity of the click was set at the psychophysical BWM threshold levels established by the 65 dB masker. The ABR conditions were designated CO, CM50, and CM80 as determined at t's of -1, -5, and -10 msec. The data were analyzed in terms of latency shift between CO and CM responses for waves I, III, and V. Latency comparisons of waves I, III, and V from CO and CM80 conditions at -1 msec (^t) revealed an increase in latency. At -5 msec, the latency shift was smaller. However, at -10 msec, CO responses produced longer latencies than those latencies recorded for CM80 responses. Latency comparisons made between CO and CM50 responses showed no latency effect. These results provide evidence that BWM is mediated, in part, at the level of the brainstem. The ABR latency data for the click and 80 dB masker followed a trend similar to the psychophysical threshold data. Specifically, shorter latencies and lower thresholds were observed as the t increased from -1 to -5 msec. This would suggest that at these intervals, the physiological mechanism involved in the BWM of the ABR and in the perception of the click are compatible.
Herbert J. Greenberg (Advisor)
Audiology

Recommended Citations

Citations

  • Rizzo, Jr., S. R. (1980). Effects of Backward Masking on Human Auditory Brainstem Responses [Doctoral dissertation, Bowling Green State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1570783750515013

    APA Style (7th edition)

  • Rizzo, Jr., Stephen. Effects of Backward Masking on Human Auditory Brainstem Responses. 1980. Bowling Green State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1570783750515013.

    MLA Style (8th edition)

  • Rizzo, Jr., Stephen. "Effects of Backward Masking on Human Auditory Brainstem Responses." Doctoral dissertation, Bowling Green State University, 1980. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1570783750515013

    Chicago Manual of Style (17th edition)

bgsu1570783750515013
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