title: Non-linear response to amplitude-modulated waves in the apical turn of the guinea pig cochlea.
abstract: Mechanical vibrations of the Hensen's cells were measured in the apical turn of the cochlea in living guinea pigs, in response to amplitude-modulated (AM) sound. The FFT of the input wave consisted of spectral components at the carrier frequency C and two sidebands (C+/-M) separated from the carrier by the modulation frequency M. The FFT of the velocity response consisted of components at: (i) the modulation frequency M, and harmonics n M; (ii) Carrier frequency C and sidebands (C+/-n M); (iii) harmonics of the carrier frequency and their side bands (2C+/-n M); (3C+/-n M); (4C+/-n M); em leader n=1,2,3, em leader,10. The carrier and the first pair of side bands were broadly tuned and nearly linear. Other components were sharply tuned and highly non-linear, suggesting a different origin. Evidence is presented that these components are generated in the non-linear stereocilia dynamics. An important function of this non-linearity is to demodulate the AM wave to extract information contained in the modulation.
authors.affiliation: Columbia University, Department of Otolaryngology/Head and Neck Surgery, 630 West 168th Street, New York, NY 10032, USA. smk3@columbia.edu
authors.forename: S M
authors.initials: SM
authors.lastname: Khanna
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D003051:Cochlea / Q000166:cytology / Q000502:physiology*; D003056:Cochlear Nerve / Q000502:physiology; D004424:Ear Canal / Q000502:physiology; D005583:Fourier Analysis; D006168:Guinea Pigs; D008954:Models, Biological; D017711:Nonlinear Dynamics; D011312:Pressure; D013016:Sound; D013997:Time Factors; D014732:Vibration