The long-term goal of Peripheral Mechanisms of Hearing is to describe the transformations that acoustic signals undergo in the ear, focusing on the vibrations of the basilar membrane, the mechanical analyzer that separates sound into its frequency components and on which rests the organ of Corti and its hair cells, which convert vibrations into bioelectric potentials;the trains of action potentials that travel along auditory-nerve fibers, carrying acoustic information to the brain;and otoacoustic emissions, sounds produced by the ears of four-limbed animals, including humans. The investigations are carried out in deeply-anesthetized chinchillas, gerbils and pigeons. The ears of chinchillas and gerbils resemble those of other mammals including humans, and therefore serve as models to study cochlear function of direct relevance to human hearing. Birds, including pigeons, are more distantly related to humans, having evolved from dinosaurs. The study of their ears serves as a comparative counterpoint to the studies in chinchilla and gerbil. Cochlear vibrations are recorded with a laser system capable of measuring displacements of atomic dimensions. Otoacoustic emissions are measured with a sensitive microphone. The electrical responses of individual auditory-nerve fibers are recorded with fine-tipped microelectrodes. Cochlear vibrations will be measured at both apical and basal regions, which principally encode low- and high-frequency sounds, respectively. The responses of auditory-nerve fibers will be studied as functions of stimulus frequency and intensity, to establish their correspondence with the underlying vibrations. Otoacoustic emissions will be measured in animals with intact ears and also in conjunction with simultaneous recordings of cochlear vibrations or responses of auditory-nerve fibers. Similar studies will also be carried in pigeons.

Public Health Relevance

The proposed studies will enhance present knowledge of cochlear vibrations, otoacoustic emissions and auditory-nerve physiology in mammals and birds. Such knowledge will be applicable to human hearing and its disorders, contributing to the improvement of audiological diagnostic procedures and to the refinement of design goals for cochlear prostheses.

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Auditory System Study Section (AUD)
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Cyr, Janet
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Northwestern University at Chicago
Other Health Professions
Schools of Arts and Sciences
United States
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Charaziak, Karolina K; Siegel, Jonathan H; Shera, Christopher A (2018) Spectral Ripples in Round-Window Cochlear Microphonics: Evidence for Multiple Generation Mechanisms. J Assoc Res Otolaryngol 19:401-419
Temchin, Andrei N; Ruggero, Mario A (2014) Spatial irregularities of sensitivity along the organ of Corti of the cochlea. J Neurosci 34:11349-54
Recio-Spinoso, Alberto; Fan, Yun-Hui; Ruggero, Mario A (2011) Basilar-membrane responses to broadband noise modeled using linear filters with rational transfer functions. IEEE Trans Biomed Eng 58:1456-65
Temchin, Andrei N; Recio-Spinoso, Alberto; Ruggero, Mario A (2011) Timing of cochlear responses inferred from frequency-threshold tuning curves of auditory-nerve fibers. Hear Res 272:178-86
Temchin, Andrei N; Ruggero, Mario A (2010) Phase-locked responses to tones of chinchilla auditory nerve fibers: implications for apical cochlear mechanics. J Assoc Res Otolaryngol 11:297-318
Recio-Spinoso, Alberto; Narayan, Shyamla S; Ruggero, Mario A (2009) Basilar membrane responses to noise at a basal site of the chinchilla cochlea: quasi-linear filtering. J Assoc Res Otolaryngol 10:471-84
Ruggero, Mario A; Temchin, Andrei N (2007) Similarity of traveling-wave delays in the hearing organs of humans and other tetrapods. J Assoc Res Otolaryngol 8:153-66
Temchin, Andrei N; Recio-Spinoso, Alberto; van Dijk, Pim et al. (2005) Wiener kernels of chinchilla auditory-nerve fibers: verification using responses to tones, clicks, and noise and comparison with basilar-membrane vibrations. J Neurophysiol 93:3635-48
Siegel, Jonathan H; Cerka, Amanda J; Recio-Spinoso, Alberto et al. (2005) Delays of stimulus-frequency otoacoustic emissions and cochlear vibrations contradict the theory of coherent reflection filtering. J Acoust Soc Am 118:2434-43
Ruggero, Mario A; Temchin, Andrei N (2005) Unexceptional sharpness of frequency tuning in the human cochlea. Proc Natl Acad Sci U S A 102:18614-9

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