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Estimating the Basilar Membrane Input-Output Function Using Fixed-Duration Masking Curves

Authors Leucke, L.
Year 2016
Thesis Type Audio Engineering project
Topic Psychoacoustics
Abstract It is known very well that the auditory system, and especially the cochlea, reacts in a nonlinear way to incoming sounds. Nevertheless, some aspects regarding the nonlinearity of the basilar membrane (BM) are not fully understood yet. Different models have been established estimating gain, compression and inputoutput function (I/O function) of the BM. As a matter of fact, the response of the BM evolves over the course of acoustic stimulation, an effect that is not taken into account in most models. One effect influencing BM response is the so-called medial olivocochlear reflex (MOCR). Based on experiments with animals, it is supposed that activation of the MOCR changes the BM I/O function. Precisely, the BM I/O function is shifted rightwards (i.e. towards high input levels) in comparison to the I/O function without influence of MOCR. As a result, a reduction in BM compression is expected. The results from previous studies with humans are inconclusive, though. In other words, the change in BM compression could not be confirmed. In this study, this hypothesis has been investigated by a method called fixedduration masking curves (FDMCs). As the method in its original form can not investigate the influence of MOCR on BM I/O function, the method has been adapted for this particular purpose. Two experiments were conducted. The results tend to confirm the change in BM compression with MOCR activation.
Supervisors Marentakis, G., Majdak, P.