Distortion product emissions from a cochlear model with nonlinear mechanoelectrical transduction in outer hair cells.
A model of cochlear mechanics is described in which force-producing outer hair cells (OHC) are embedded in a passive cochlear partition. The OHC mechanoelectrical transduction current is nonlinearly modulated by reticular-lamina (RL) motion, and the resulting change in OHC membrane voltage produces contraction between the RL and the basilar membrane (BM). Model parameters were chosen to produce a tonotopic map typical of a human cochlea. Time-domain simulations showed compressive BM displacement responses typical of mammalian cochleae. Distortion product (DP) otoacoustic emissions at 2f(1)-f(2) are plotted as isolevel contours against primary levels (L(1),L(2)) for various primary frequencies f(1) and f(2) (f(1)<f(2)). The L(1) at which the DP reaches its maximum level increases as L(2) increases, and the slope of the "optimal" linear path decreases as f(2)/f(1) increases. When primary levels and f(2) are fixed, DP level is band passed against f(1). In the presence of a suppressor, DP level generally decreases as suppressor level increases and as suppressor frequency gets closer to f(2); however, there are exceptions. These results, being similar to data from human ears, suggest that the model could be used for testing hypotheses regarding DP generation and propagation in human cochleae.
Liu
Yi-Wen
YW
Boys Town National Research Hospital, 555 North 30th Street, Omaha, Nebraska 68131, USA.
Neely
Stephen T
ST
D000161:Acoustic Stimulation; D001489:Basilar Membrane / Q000502:physiology; D003051:Cochlea / Q000502:physiology*; D003198:Computer Simulation; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D006801:Humans; D040542:Mechanotransduction, Cellular; D008564:Membrane Potentials; D008954:Models, Biological; D017711:Nonlinear Dynamics; D009716:Numerical Analysis, Computer-Assisted; D017084:Otoacoustic Emissions, Spontaneous; D010898:Pitch Perception; D011930:Reaction Time; D013997:Time Factors