Effects of click polarity on ABR peak latency and morphology in a clinical population

Magnitude and direction of click phase-related shifts for ABR peaks I through V and the major interpeak intervals were measured for normal ears and ears with varying degrees of high frequency (HF) hearing loss. Latencies of Waves I and V were relatively stable with inversion of stimulus phase in ears with normal hearing and mild degrees of HF hearing loss, but the incidence of substantial phase-induced latency shifts increased in proportion to pure tone deficits. Waves II and IV demonstrated the greatest shifts in all hearing loss categories. Summation of dissimilar responses obtained with opposite acoustic polarities may result in response degradation. A number of phase-specific ABR abnormalities are discussed. In the greater proportion of ears, rarefaction clicks were the more productive stimulus in eliciting the full complement of response peaks.