Flexible Solver For 1-D Cochlear Partition Simulations

2016 ◽  
Author(s):  
Pablo E. Riera ◽  
Manuel C. Eguía
Keyword(s):  
Cochlear Partition

Mechanical Responses to Two-Tone Distortion Products in the Apical and Basal Turns of the Mammalian Cochlea

1997 ◽  
Vol 78 (1) ◽  
pp. 261-270 ◽  
Author(s):  
N. P. Cooper ◽  
W. S. Rhode
Keyword(s):  
Guinea Pig ◽  
Sound Pressure ◽  
Basal Turn ◽  
Mechanical Responses ◽  
Acoustic Stimuli ◽  
Distortion Products ◽  
Guinea Pig Cochlea ◽  
Absolute Magnitudes ◽  
Cochlear Partition ◽  
Frequency Ratios

Cooper, N. P. and W. S. Rhode. Mechanical responses to two-tone distortion products in the apical and basal turns of the mammalian cochlea. J. Neurophysiol. 78: 261–270, 1997. Mechanical responses to one- and two-tone acoustic stimuli were recorded from the cochlear partition in the apical turn of the chinchilla cochlea, the basal turn of the guinea pig cochlea, and the hook region of the guinea pig cochlea. The most sensitive or “best” frequencies (BFs) for the sites studied were ∼500 Hz, 17 kHz, and 30 kHz, respectively. Responses to the cubic difference tone (CDT), 2 F 1 − F 2 (where F 1 and F 2 are the frequencies of the primary stimuli), were characterized at each site. Responses to the quadratic difference tone (QDT), F 2 − F 1, were also characterized in the apical turn preparations (QDT responses were too small to measure in the basal cochlea). The observed responses to BF QDTs and CDTs and to BF CDTs at each site appeared similar in many ways; the relative magnitudes of the responses were highest at low-to-moderate sound pressure levels (SPLs), for example, and the absolute magnitudes grew nonmonotonically with increases in the level of either primary ( L 1 or L 2) alone. The peak effective levels of the CDT and QDT responses were also similar, at around −20 dB re L 1 and/or L 2. In other respects, however, the responses to CDTs and QDTs and to BF CDTs at each site behaved quite differently. At low-to-moderate SPLs, for example, most CDT phase leads decreased with increases in either L 1 or L 2, whereas most QDT phase leads increased with increasing L 1 and varied little with L 2. Most CDT responses also varied monotonically with equal-level primaries (i.e., when L 1 = L 2), whereas most QDT responses varied nonmonotonically. Different responses also varied in different ways when F 1 and F 2 were varied. Apical turn QDT responses were observed over a very wide F 1/ F 2 range ( F 1 =1–12 kHz), but were usually largest for stimuli <2–4 kHz. Apical turn CDT levels decreased (at rates of ∼40–80 dB/octave) only when the frequency ratio F 2/ F 1 increased beyond ∼1.4–1.5. In the basal turn and hook regions, the CDT levels depended nonmonotonically on F 2/ F 1, with the eventual rates of decrease being ∼200 dB/octave. Optimal frequency ratios for the CDT increased from ( F 2 < 1.1 F 1) to ( F 2 ≈ 1.2 F 1) with increasing SPL in the basal turn, but were stable at around F 2/ F 1 ≈ 1.05 in the hook region. CDT phase leads tended to increase with increasing F 2/ F 1 in all three regions of the cochlea, particularly at low-to-moderate SPLs. These findings are discussed in relation to previous studies of cochlear mechanics, physiology, and psychophysics.

Representation of cochlea within primary auditory cortex in the cat

1975 ◽  
Vol 38 (2) ◽  
pp. 231-249 ◽  
Author(s):  
M. M. Merzenich ◽  
P. L. Knight ◽  
G. L. Roth
Keyword(s):  
Auditory Cortex ◽  
Frequency Band ◽  
Constant Width ◽  
Primary Auditory Cortex ◽  
Cortical Surface ◽  
Cortical Layers ◽  
Secondary Field ◽  
Mapping Techniques ◽  
Cochlear Partition ◽  
Tonal Stimuli

The representation of sound frequency (and of the cochlear partition) within primary auditory cortex has been investigated with use of microelectrode-mapping techniques in a series of 25 anesthetized cats. Among the results were the following: 1) Within vertical penetrations into AI, best frequency and remarkably constant for successively studied neurons across the active middle and deep cortical layers. 2) There is an orderly representation of frequency (and of represented cochlear place) within AI. Frequency is rerepresented across the mediolateral dimension of the field. On an axis perpendicular to this plane of rerepresentation, best-frequency (represented cochlear place) changes as a simple function of cortical location. 3) Any given frequency band (or sector of the cochlear partition) is represented across a belt of cortex of nearly constant width that runs on a nearly straight axis across AI. 4) There is a disproportionately large cortical surface representation of the highest-frequency octaves (basal cochlea) within AI. 5) The primary and secondary field locations were somewhat variable, when referenced to cortical surface landmarks. 6) Data from long penetrations passing down the rostral bank of the posterior ectosylvian sulcus were consistent with the existence of a vertical unit of organization in AI, akin to cortical columns described in primary visual and somatosensory cortex. 7) Responses to tonal stimuli were encountered in fields dorsocaudal, caudal, ventral, and rostral to AI. There is an orderly representation of the cochlea within the field rostal to AI, with a reversal in best frequencies across its border with AI. 8) Physiological definitions of AI boundaries are consistent with their cytoarchitectonic definition. Some of the implications of these findings are discussed.

A model cochlear partition involving longitudinal elasticity

2002 ◽  
Vol 112 (2) ◽  
pp. 576-589 ◽  
Author(s):  
Taha S. A. Jaffer ◽  
Hans Kunov ◽  
Willy Wong
Keyword(s):  
Cochlear Partition

scholarly journals Effects of coiling on the micromechanics of the mammalian cochlea

2005 ◽  
Vol 2 (4) ◽  
pp. 341-348 ◽  
Author(s):  
Hongxue Cai ◽  
Daphne Manoussaki ◽  
Richard Chadwick
Keyword(s):  
Outer Hair Cell ◽  
Basilar Membrane ◽  
Travelling Waves ◽  
Organ Of Corti ◽  
Tectorial Membrane ◽  
Governing Equations ◽  
Element Analysis ◽  
Curvature Effects ◽  
Curvilinear Coordinate ◽  
Cochlear Partition

The cochlea transduces sound-induced vibrations in the inner ear into electrical signals in the auditory nerve via complex fluid–structure interactions. The mammalian cochlea is a spiral-shaped organ, which is often uncoiled for cochlear modelling. In those few studies where coiling has been considered, the cochlear partition was often reduced to the basilar membrane only. Here, we extend our recently developed hybrid analytical/numerical micromechanics model to include curvature effects, which were previously ignored. We also use a realistic cross-section geometry, including the tectorial membrane and cellular structures of the organ of Corti, to model the apical and basal regions of a guinea-pig cochlea. We formulate the governing equations of the fluid and solid domains in a curvilinear coordinate system. The WKB perturbation method is used to treat the propagation of travelling waves along the coiled cochlear duct, and the O (1) system of the governing equations is solved in the transverse plane using finite-element analysis. We find that the curvature of the cochlear geometry has an important functional significance; at the apex, it greatly increases the shear gain of the cochlear partition, which is a measure of the bending efficiency of the outer hair cell stereocilia.

Incomplete Cochlear Partition Type II Variants as an Indicator of Congenital Partial Deafness

2012 ◽  
Vol 33 (6) ◽  
pp. 957-962 ◽  
Author(s):  
Jennifer F. Ha ◽  
Bradley Wood ◽  
Jay Krishnaswamy ◽  
Gunesh P. Rajan
Keyword(s):  
Type Ii ◽  
Cochlear Partition
Sign in / Sign up

Export Citation Format

Share Document