Effect of hearing loss and age on human cochlear traveling wave delay

Abstract

The cochlear traveling wave delay can be derived from distortion product emission (DPE) phase measurements [Kimberley et al., 1993]. By testing ears with mild cochlear hearing damage as well as ears with normal hearing thresholds (~25 dB SPL, ANSI 1969), it was shown that cochlear latencies measured in this way are not significantly affected by hearing loss. Traveling wave delay however does increase slightly with age. Optimal f2/ fi ratio and associated DPE amplitude were also tested for age or threshold effects. The f2/fi ratio remained unaffected by age or hearing loss, but decreased with increasing frequency. The maximum DPE amplitude decreased with both advancing age and with increasing pure-tone threshold, so it was impossible to isolate the contribution of each individual factor. The linearity between maximum DPE amplitude and threshold, at the frequencies tested, shows potential for clinical use.