Cochlear impulse responses resolved into sets of gammatones: the case for beating of closely spaced local resonances
Autor: | Hero P. Wit, Andrew Bell |
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Rok vydání: | 2018 |
Předmět: |
0301 basic medicine
AUDITORY-NERVE Tectorial membrane Impulse response Acoustics Biophysics Instantaneous frequency lcsh:Medicine Overfitting Impulse (physics) Instantaneous phase General Biochemistry Genetics and Molecular Biology INTERFERENCE PATTERNS TECTORIAL MEMBRANE 03 medical and health sciences 0302 clinical medicine CLICK RESPONSES MECHANICAL WAVE-FORM medicine Waveform Time domain Mathematical Biology Coupled oscillators Physics General Neuroscience lcsh:R Computational Biology General Medicine Basilar membrane FREQUENCY GLIDES TIME-DOMAIN Gammatones MODEL 030104 developmental biology medicine.anatomical_structure FILTER Otorhinolaryngology Beating BASILAR-MEMBRANE RESPONSES General Agricultural and Biological Sciences 030217 neurology & neurosurgery Neuroscience |
Zdroj: | PeerJ, 6:6016. PEERJ INC PeerJ PeerJ, Vol 6, p e6016 (2018) |
ISSN: | 2167-8359 |
Popis: | Gammatones have had a long history in auditory studies, and recent theoretical work suggests they may play an important role in cochlear mechanics as well. Following this lead, the present paper takes five examples of basilar membrane impulse responses and uses a curve-fitting algorithm to decompose them into a number of discrete gammatones. The limits of this ‘sum of gammatones’ (SOG) method to accurately represent the impulse response waveforms were tested and it was found that at least two and up to six gammatones could be isolated from each example. Their frequencies were stable and largely independent of stimulus parameters. The gammatones typically formed a regular series in which the frequency ratio between successive members was about 1.1. Adding together the first few gammatones in a set produced beating-like waveforms which mimicked waxing and waning, and the instantaneous frequencies of the waveforms were also well reproduced, providing an explanation for frequency glides. Consideration was also given to the impulse response of a pair of elastically coupled masses—the basis of two-degree-of-freedom models comprised of coupled basilar and tectorial membranes—and the resulting waveform was similar to a pair of beating gammatones, perhaps explaining why the SOG method seems to work well in describing cochlear impulse responses. A major limitation of the SOG method is that it cannot distinguish a waveform resulting from an actual physical resonance from one derived from overfitting, but taken together the method points to the presence of a series of closely spaced local resonances in the cochlea. |
Databáze: | OpenAIRE |
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