A comparison of AP and ABR tuning characteristics in the guinea pig

Abstract

AP and ABR tuning curves were measured using a forward‐masking paradigm in guinea pigs with chronically implanted electrodes. Measurements were made before exposure to wide‐band noise and at several intervals after exposure. The noise exposure was sufficient to produce temporary threshold shifts up to 60 dB lasting several days and resulted in a systematic widening of both AP and ABR tuning curves and a reduction in tip‐to‐tail ratios. No significant differences were found between simultaneously recorded AP and ABR tuning curves as measured by Q10, tip‐to‐tail ratio, or the slope of the tuning curves. Tuning curves obtained by measuring AP and ABR response latency as a function of masker level, showed similar form and changes with hearing loss to those based on amplitude of response. The similarities between AP and ABR tuning characteristics provide evidence that the ABR is sensitive enough to peripheral changes to be a useful tool in the study of auditory frequency selectivity.