Sixty-eight fixed frequency Bekesy tracings with patterns suggesting retrocochlear lesions were analyzed. Continuous tone (C) threshold minus interrupted tone (I) threshold, amplitudeC, amplitudeCre amplitudeI, rate of decayC, and pattern category were determined for each tracing. Medical diagnoses were related to these characteristics and a means of interpreting Bekesy audiograms for cochlear or retrocochlear malfunction is suggested in a table of probabilities drawn from the data. Significant indicators of retrocochlear lesions were thresholdC minus thresholdI > 26 dB, rate of decayC > 0.49 dB/sec, and decay pattern A, all measured at low, mid, and high frequencies. The best indicator of cochlear lesions was amplitudeC < 6 dB at low frequencies. Contrary to expectation, neither small amplitudeC at mid and high frequencies nor a relative amplitude measure at any frequency was found to be an effective discriminator of the site of lesion.
Ehrlich CH. Analysis of Selected Fixed Frequency Bekesy Tracings. Arch Otolaryngol. 1971;93(1):12–24. doi:10.1001/archotol.1971.00770060044003