Frequency information in the auditory brainstem response evoked by tonal transients

The auditory brainstem response (ABR) is a composite of potentials generated by neural activity stemming from several regions of the cochlea. A derivation technique is described for reducing the contributions to the ABR that arise from frequencies outside of the frequency band of interest. The technique treats averaged waveforms in an algebraic manner and uses a method of successive substitutions to obtain a derived waveform. The recorded and derived ABR waveforms were analyzed with respect to changes of latency and morphology. The behavior of the waveform components of the derived regional responses was in accord with the data of other studies in which narrow-band responses were derived from waveforms produced by high-pass masking of click stimuli. Frequency information was thus extracted from the ABR without the simultaneous presence of other stimuli as in masking-based derivations. The method of successive substitutions used with brief transient stimuli of different frequencies appears to yield derived ABRs that reflect activity from different cochlear regions.