Relations among measures of the slow cortical response (SCR) and Absolute Magnitude Estimation (AME) loudness judgments in young normal-hearing adults
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xiii, 128 pages
DepartmentTowson University. Department of Audiology, Speech-Language Pathology and Deaf Studies
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The goal of the current study was to determine the relation, if any, between behavioral loudness judgments, using the Absolute Magnitude Estimation (AME) protocol, and the response properties of the slow cortical response (SCR) to 2000-Hz tone-burst stimuli. A secondary goal of the study was to determine the relation, if any, between the subjects' loudness judgments and the annoyance ratings that accompanied these loudness judgments. Eleven normal-hearing young adults participated in the study. Subjects provided an AME loudness judgment rating as well as an annoyance rating to a train of seven 2000-Hz tonal stimuli that were presented from 10 to 80 dB nHL, in 10 dB increments. Following the loudness judgment ratings, slow cortical responses were recorded for each subject at each stimulus intensity. The acoustic stimuli for the slow cortical response recordings consisted of the same 2000-Hz tone bursts. After the slow cortical response was recorded at each stimulus intensity, each subject was asked to provide judgments of both the loudness and annoyance of these 2000-Hz tonal stimuli at that stimulus intensity. The peak-to-peak amplitude values of waves P1-N1 and N1-P2, as well as the absolute latency values of waves P1, N1, and P2, were measured to explore the possible relations, if any, of these response measurements with the behavioral growth of loudness for these tonal stimuli. Each response property of the slow cortical response was plotted in a scatter plot as a function of stimulus intensity. Linear regression analyses were fitted to each response data set separately and Spearman's rank correlation values were calculated. The peak-to-peak amplitude values of wave N1-P2 have the strongest correlation to the growth of loudness as a function of stimulus intensity in comparison to the response latencies of the various peaks. Future studies should continue to look into the slow cortical response as a possible objective measure to characterize loudness growth in difficult to test populations.