Enhanced Place Specificity of the Parallel Auditory Brainstem Response: An Electrophysiological Study

Abstract

PurposeThis study investigates the effect of parallel stimulus presentation on the place specificity of the auditory brainstem response (ABR) in human listeners. Frequency-specific stimuli do not guarantee a response place on the cochlea corresponding only to that characteristic frequency – especially for brief and high-level stimuli. Masking techniques can ensure place specific responses, and prior modeling has suggested parallel presentation of frequency-specific stimuli improves place specificity. We tested this hypothesis experimentally here, comparing the place specificity of responses to serial and parallel stimuli at two stimulus frequencies and three stimulus rates.MethodsStimuli were presented alongside high-pass filtered noise with a varied cutoff frequency. Latencies of the ABRs were examined to assess place specificity of responses. Response bands were derived by subtracting responses from different high pass noise conditions. The response amplitude from each derived response band was then used to determine how much individual frequency regions of the auditory system were contributing to the overall response.ResultsWe find that parallel presentation improves place specificity of ABRs for the lower stimulus frequency and at higher stimulus rates. At a higher stimulus frequency, serial and parallel presentation were equally place specific.ConclusionParallel presentation can provide more place specific responses than serial for lower stimulus frequencies. The improvement increases with higher stimulus rates and is in addition to the parallel ABR’s primary benefit of faster test times.