Sound pressures in the basal turn of the cat cochlea

Nedzelnitsky, Victor

doi:10.1121/1.385200

Cited by 136 publications

(91 citation statements)

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“…7). Similar results were recorded by Puria et al (1997) in scala vestibuli in human temporal bones as well as by Nedzelnitsky (1980) for both scalae in the cat. Close inspection of our data shows that this non-ossicularly conducted sound appears nearly equally in scala vestibuli and scala tympani.…”

Section: Effect Of Ossicular Discontinuity On Sound Transmissionsupporting

confidence: 79%

“…The phases were generally similar at higher frequencies. Similar findings were reported in cat (Nedzelnitsky 1980) and the guinea pig (Dancer and Franke 1980).…”

Section: Pressure Measurements In Cochlear Scalaesupporting

confidence: 77%

“…Details of the calibration method can be found in Nedzelnitsky (1980) and Schloss and Strasberg (1962). In initial experiments, calibrations performed in water and in air were found to agree.…”

Section: Pressure Sensormentioning

confidence: 99%

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Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

Nakajima

Dong

Olson

et al. 2008

JARO

175

226

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We present the first simultaneous sound pressure measurements in scala vestibuli and scala tympani of the cochlea in human cadaveric temporal bones. The technique we employ, which exploits microscale fiberoptic pressure sensors, enables the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. In our results, the sound pressure in scala vestibuli (P SV ) was much greater than scala tympani pressure (P ST ), except for very low and high frequencies where P ST significantly affected the input to the cochlea. The differential pressure (P SV − P ST ) is a superior measure of ossicular transduction of sound compared to P SV alone: (P SV −P ST ) was reduced by 30 to 50 dB when the ossicular chain was disarticulated, whereas P SV was not reduced as much. The middle ear gain P SV /P EC and the differential pressure normalized to ear canal pressure (P SV − P ST )/P EC were generally bandpass in frequency dependence. At frequencies above 1 kHz, the group delay in the middle ear gain is about 83 μs, over twice that of the gerbil. Concurrent measurements of stapes velocity produced estimates of cochlear input impedance, the differential impedance across the partition, and round window impedance. The differential impedance was generally resistive, while the round window impedance was consistent with compliance in conjunction with distributed inertia and damping. Our technique of measuring differential pressure can be used to study inner ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round window stimulation and bone conduction)-situations that cannot be completely quantified by measurements of stapes velocity or scala vestibuli pressure by themselves.

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Section: Effect Of Ossicular Discontinuity On Sound Transmissionsupporting

confidence: 79%

“…The phases were generally similar at higher frequencies. Similar findings were reported in cat (Nedzelnitsky 1980) and the guinea pig (Dancer and Franke 1980).…”

Section: Pressure Measurements In Cochlear Scalaesupporting

confidence: 77%

See 1 more Smart Citation

Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

Nakajima

Dong

Olson

et al. 2008

JARO

175

226

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“…Although the ear-canal to cochlea pressure transfer function was not calculated by Funnell et al (17), the pressure transfer function magnitude will likely have the same slope as the umbo displacement, which is also Ϫ12 dB/octave, due to the lever model of the ossicles. This is inconsistent with measurements (21,22), where the slope is less than Ϫ6 dB/octave. In the present model, the average slope of the magnitude is closer to approximately Ϫ4 dB/octave (Fig.…”

Section: Discussioncontrasting

confidence: 53%

“…Fig. 2a compares the ear-canal-pressure to vestibule-pressure transfer function, or the middle-ear pressure gain, of the model to the range of experimental values (21,22). The measured magnitude varies by approximately Ϯ10 dB, which is not atypical for physiological measurements.…”

Section: Resultsmentioning

confidence: 99%

The discordant eardrum

Fay¹,

Puria

Steele³

2006

Proc. Natl. Acad. Sci. U.S.A.

124

141

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At frequencies above 3 kHz, the tympanic membrane vibrates chaotically. By having many resonances, the eardrum can transmit the broadest possible bandwidth of sound with optimal sensitivity. In essence, the eardrum works best through discord. The eardrum's success as an instrument of hearing can be directly explained through a combination of its shape, angular placement, and composition. The eardrum has a conical asymmetrical shape, lies at a steep angle with respect to the ear canal, and has organized radial and circumferential collagen fiber layers that provide the scaffolding. Understanding the role of each feature in hearing transduction will help direct future surgical reconstructions, lead to improved microphone and loudspeaker designs, and provide a basis for understanding the different tympanic membrane structures across species. To analyze the significance of each anatomical feature, a computer simulation of the ear canal, eardrum, and ossicles was developed. It is shown that a cone-shaped eardrum can transfer more force to the ossicles than a flat eardrum, especially at high frequencies. The tilted eardrum within the ear canal allows it to have a larger area for the same canal size, which increases sound transmission to the cochlea. The asymmetric eardrum with collagen fibers achieves optimal transmission at high frequencies by creating a multitude of deliberately mistuned resonances. The resonances are summed at the malleus attachment to produce a smooth transfer of pressure across all frequencies. In each case, the peculiar properties of the eardrum are directly responsible for the optimal sensitivity of this discordant drum.collagen fibers ͉ hearing sensitivity ͉ middle ear ͉ transducers T he function of the middle ear in terrestrial mammals is to transfer acoustic energy between the air of the ear canal to the fluid of the inner ear. The first and crucial step of the transduction process takes place at the tympanic membrane, which converts sound pressure in the ear canal into vibrations of the middle ear bones. Understanding how the tympanic membrane manages this task so successfully over such a broad range of frequencies has been a subject of research since Helmholtz's publication in 1868 (1, 2).Even though the function of the eardrum is clear and the anatomy of the eardrum is well characterized, the connection between the anatomical features and the ability of the eardrum to transduce sound has been missing. The missing structurefunction relationships can be summarized by the following three questions. Why does the mammalian eardrum have its distinctive conical and toroidal shape? What is the advantage of its angular placement in the ear canal? What is the significance of its highly organized radial and circumferential fibers?The shape of the human and feline eardrum is known from detailed Moiré interferometry contour maps (refs. 3 and 4 and Fig. 1a). From the contour maps, three-dimensional reconstructions reveal the striking similarity of the two eardrums. In both cases, the eardrum has an ell...

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The piezoelectric cochlear implant: Concept, feasibility, challenges, and issues

Mukherjee

Roseman

Willging

2000

J. Biomed. Mater. Res.

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A better understanding of the fundamental phenomena occurring in both the healthy and the artificially stimulated cochlea will greatly aid in the engineering of more effective cochlear implant devices and will, in general, enhance mankind's knowledge of inner ear function. This study was initiated to probe the feasibility of use of artificial piezoelectric transducer devices, both for the understanding of cochlear phenomena and as a possible cochlear implant. Aspects of feasibility of such an implant, the issues involved, the materials science challenges that need to be overcome to fabricate such a device, and results from initial in vivo experiments are discussed.

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Sound pressures in the basal turn of the cat cochlea

Cited by 136 publications

References 0 publications

Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

The discordant eardrum

The piezoelectric cochlear implant: Concept, feasibility, challenges, and issues

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