Abstract
Two objective measures of human cochlear tuning, using stimulus-frequency otoacoustic emissions
(SFOAE), have been proposed. One measure used SFOAE phase-gradient delay and the other twotone
suppression (2TS) tuning curves. Here, it is hypothesized that the two measures lead to different
frequency functions in the same listener. Two experiments were conducted in ten young adult
normal-hearing listeners in three frequency bands (1-2 kHz, 3-4 kHz and 5-6 kHz). Experiment 1
recorded SFOAE latency as a function of stimulus frequency, and experiment 2 recorded 2TS isoinput
tuning curves. In both cases, the output was converted into a sharpness-of-tuning factor based
on the equivalent rectangular bandwidth. In both experiments, sharpness-of-tuning curves were
shown to be frequency dependent, yielding sharper relative tuning with increasing frequency. Only
a weak frequency dependence of the sharpness-of-tuning curves was observed for experiment 2,
consistent with objective and behavioural estimates from the literature. Most importantly, the absolute
difference between the two tuning estimates was very large and statistically significant. It is
argued that the 2TS estimates of cochlear tuning likely represents the underlying properties of the
suppression mechanism, and not necessarily cochlear tuning. Thus the phase-gradient delay estimate
is the most likely one to reflect cochlear tuning.
Original language | English |
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Journal | Journal of the Acoustical Society of America |
Volume | 129 |
Issue number | 6 |
Pages (from-to) | 3797-3807 |
ISSN | 0001-4966 |
DOIs | |
Publication status | Published - 2011 |
Keywords
- Cochlear mechanics
- Hearing
- Otoacoustic emissions