THE EFFECTS OF REVERSING THE POLARITY OF FREQUENCY-LIMITED SINGLE-CYCLE STIMULI ON THE HUMAN AUDITORY BRAIN-STEM RESPONSE

This study was conducted to investigate morphologic differences in the ABR as a result of reversing the stimulus polarity of frequency-limit ed single-cycle stimuli in normal-hearing subjects. The results clearl y demonstrate that large latency differences occur between condensatio n and rarefaction stimuli for low-frequency stimuli. It is believed th at polarity-specific latencies are a result of the highly phase-sensit ive neural elements tuned to low-frequency stimuli. In the majority of test subjects the rarefaction stimulus produced shorter absolute wave latencies; however, in a small number of subjects, significantly shor ter latencies were elicited with the condensation stimulus. It is beli eved that differences may occur from varying summation patterns of inn er hair cell depolarization between subjects which would be consistent over time within the same subject.