scholarly journals Revealing the actions of the human cochlear basilar membrane at low frequency

2022 ◽  
Vol 104 ◽  
pp. 106043
Author(s):  
Wenjuan Yao ◽  
Junyi Liang ◽  
Liujie Ren ◽  
Jianwei Ma ◽  
Zhengshan Zhao ◽  
...  
Keyword(s):  
Basilar Membrane ◽  
Low Frequency

scholarly journals Hearing at threshold intensities: by slow mechanical traveling waves or by fast cochlear fluid pressure waves

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haim Sohmer
Keyword(s):  
Soft Tissue ◽  
Hair Cells ◽  
Traveling Wave ◽  
Basilar Membrane ◽  
Fluid Pressure ◽  
Low Frequency ◽  
Frequency Discrimination ◽  
Outer Hair Cells ◽  
Common Mechanism ◽  
Frequency Stimulation

The three modes of auditory stimulation (air, bone and soft tissue conduction) at threshold intensities are thought to share a common excitation mechanism: the stimuli induce passive displacements of the basilar membrane propagating from the base to the apex (slow mechanical traveling wave), which activate the outer hair cells, producing active displacements, which sum with the passive displacements. However, theoretical analyses and modeling of cochlear mechanics provide indications that the slow mechanical basilar membrane traveling wave may not be able to excite the cochlea at threshold intensities with the frequency discrimination observed. These analyses are complemented by several independent lines of research results supporting the notion that cochlear excitation at threshold may not involve a passive traveling wave, and the fast cochlear fluid pressures may directly activate the outer hair cells: opening of the sealed inner ear in patients undergoing cochlear implantation is not accompanied by threshold elevations to low frequency stimulation which would be expected to result from opening the cochlea, reducing cochlear impedance, altering hydrodynamics. The magnitude of the passive displacements at threshold is negligible. Isolated outer hair cells in fluid display tuned mechanical motility to fluid pressures which likely act on stretch sensitive ion channels in the walls of the cells. Vibrations delivered to soft tissue body sites elicit hearing. Thus, based on theoretical and experimental evidence, the common mechanism eliciting hearing during threshold stimulation by air, bone and soft tissue conduction may involve the fast-cochlear fluid pressures which directly activate the outer hair cells.

Tinnitus: some thoughts about its origin

1984 ◽  
Vol 98 (S9) ◽  
pp. 31-37 ◽  
Author(s):  
J. J. Eggermont
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Basilar Membrane ◽  
Stimulus Frequency ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Ear Ossicles ◽  
Stimulus Transduction ◽  
Low Levels ◽  
Inner Ear Fluids

An auditory sensation follows generally as the result of the sequence stimulus, transduction, coding, transformation and sensation. This is then optionally followed by perception and a reaction. The stimulus is usually airborne sound causing movements of the tympanic membrane, the middle ear ossicles, the inner ear fluids and the basilar membrane. The movements of the basilar membrane are dependent on stimulus frequency: high frequency tones excite only the basal part of the cochlea, regardless of the stimulus intensity; low frequency tones at low levels only excite the so-called place specific region at the apical end but at high levels (above 60–70 dB SPL) cause appreciable movement of the entire basilar membrane. Basilar membrane tuning is as sharp as that of inner hair cells or auditory nerve fibers (Sellick et al., 1982) at least in the basal turn of animals that have a cochlea in physiologically impeccable condition.

Influence of ossicular chain malformation on the performance of round-window stimulation: A finite element approach

2019 ◽  
Vol 233 (5) ◽  
pp. 584-594 ◽  
Author(s):  
Houguang Liu ◽  
Hu Zhang ◽  
Jianhua Yang ◽  
Xinsheng Huang ◽  
Wen Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Middle Ear ◽  
Basilar Membrane ◽  
Round Window ◽  
Low Frequency ◽  
Element Model ◽  
Ossicular Chain ◽  
Asymmetric Structure ◽  
Low Frequencies ◽  
Stapes Fixation

As a novel application of implantable middle ear hearing device, round-window stimulation is widely used to treat hearing loss with middle ear disease, such as ossicular chain malformation. To evaluate the influence of ossicular chain malformations on the efficiency of the round-window stimulation, a human ear finite element model, which incorporates cochlear asymmetric structure, was constructed. Five groups of comparison with experimental data confirmed the model’s validity. Based on this model, we investigated the influence of three categories of ossicular chain malformations, that is, incudostapedial disconnection, incus and malleus fixation, and fixation of the stapes. These malformations’ effects were evaluated by comparing the equivalent sound pressures derived from the basilar membrane displacement. Results show that the studied ossicular chain malformations mainly affected the round-window simulation’s performance at low frequencies. In contrast to the fixation of the ossicles, which mainly deteriorates round-window simulation’s low-frequency performance, incudostapedial disconnection increases this performance, especially in the absence of incus process and stapes superstructure. Among the studied ossicular chain malformations, the stapes fixation has a much more severe impact on the round-window stimulation’s efficiency. Thus, the influence of the patients’ ossicular chain malformations should be considered in the design of the round-window stimulation’s actuator. The low-frequency output of the round-window simulation’s actuator should be enhanced, especially for treating the patients with stapes fixation.

Measurement of Vibration of the Basilar Membrane in the Squirrel Monkey

1974 ◽  
Vol 83 (5) ◽  
pp. 619-625 ◽  
Author(s):  
William S. Rhode
Keyword(s):  
Resonant Frequency ◽  
Squirrel Monkey ◽  
Basilar Membrane ◽  
Low Frequency ◽  
Wave Theory ◽  
Resonance Curve ◽  
Nerve Fibers ◽  
Neural Data ◽  
Oscillatory Response ◽  
Resonance Curves

The Mössbauer technique, which can be used to measure very small velocities, on the order of 0.2 mm/sec, has been used to measure the response of the basilar membrane to tones and clicks in squirrel monkeys. The results verify that there is a mechanical frequency analysis performed in the cochlea and that the traveling wave theory holds true. The resonance curves indicate that the tuning of the basilar membrane is greater than was thought. The basilar membrane in the 7–8 kHz region of the cochlea vibrates nonlinearly at frequencies near the “resonant frequency.” The click response shows that the “tail” of the decaying oscillatory response does not decrease in proportion to click amplitude while the early displacements of the basilar membrane have a nearly linear relationship with click amplitude. These results are in good agreement with the results of the measurements using tones as stimuli. Experiments examining postmortem behavior of the basilar membrane indicate a rapid decrease in the sensitivity of vibration along with a decrease of up to one octave in the “resonant” frequency within a six hour period after the animal's death. The shift in resonant frequency is accompanied by a corresponding shift in the phase characteristic. The low frequency slope of the resonance curve becomes 6 dB/octave exactly as Békésy found while the high frequency slope decreases slightly. Comparison of the mechanical resonance curves with the neural data for single auditory nerve fibers in the squirrel monkey indicates that the exquisite tuning exhibited in the nerve cannot be explained solely on the basis of the mechanical behavior of the basilar membrane.

A mathematical model of the dynamics of the inner ear

1982 ◽  
Vol 116 ◽  
pp. 59-75 ◽  
Author(s):  
Mark H. Holmes
Keyword(s):  
Cross Section ◽  
Basilar Membrane ◽  
Three Dimensional ◽  
Low Frequency ◽  
Transverse Cross Section ◽  
Frequency Theory ◽  
Slender Body Theory ◽  
High Frequencies ◽  
Hearing Range ◽  
Body Theory

A three-dimensional hydroelastic model of the dynamical motion in the cochlea is analysed. The fluid is Newtonian and incompressible, and the basilar membrane is modelled as an orthotropic elastic plate. Asymptotic expansions are introduced, based on slender-body theory and the relative high frequencies in the hearing range, which reduce the problem to an eigenvalue problem in the transverse cross-section. After this, an example is worked out and a comparison is made with experiment and the earlier low-frequency theory.

Two-tone suppression in the basilar membrane of the cochlea: mechanical basis of auditory-nerve rate suppression

1992 ◽  
Vol 68 (4) ◽  
pp. 1087-1099 ◽  
Author(s):  
M. A. Ruggero ◽  
L. Robles ◽  
N. C. Rich
Keyword(s):  
Auditory Nerve ◽  
Outer Hair Cell ◽  
Basilar Membrane ◽  
Frequency Tuning ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Oval Window ◽  
Outer Hair Cells ◽  
Probe Intensity ◽  
Rate Suppression

1. The vibratory response to two-tone stimuli was measured in the basilar membrane of the chinchilla cochlea by means of the Mossbauer technique or laser velocimetry. Measurements were made at sites with characteristic frequency (CF, the frequency at which an auditory structure is most sensitive) of 7-10 kHz, located approximately 3.5 mm from the oval window. 2. Two-tone suppression (reduction in the response to one tone due to the presence of another) was demonstrated for CF probe tones and suppressor tones with frequencies both higher and lower than CF, at moderately low stimulus levels, including probe-suppressor combinations for which responses to the suppressor were lower than responses to the probe tone alone. 3. For a fixed suppressor tone, suppression magnitude decreased as a function of increasing probe intensity. 4. The magnitude of suppression increased monotonically with suppressor intensity. 5. The rate of growth of suppression magnitude with suppressor intensity was higher for suppressors in the region below CF than for those in the region above CF. 6. For low-frequency suppressor tones, suppression magnitude varied periodically, attaining one or two maxima within each period of the suppressor tone. 7. Suppression was frequency tuned: for either above-CF or below-CF suppressor tones, suppression magnitude reached a maximum for probe frequencies near CF. 8. Cochlear damage or death diminished or abolished suppression. There was a clear positive correlation between magnitude of suppression and basilar-membrane sensitivity for responses to CF tones. 9. Suppression tended to be accompanied by small phase lags in responses to CF probe tones. 10. Because all of the features of two-tone suppression at the basilar membrane match qualitatively (and, generally, also quantitatively) the features of two-tone rate suppression in auditory-nerve fibers, it is concluded that neural two-tone rate suppression originates in mechanical phenomena at the basilar membrane. 11. Because the lability of mechanical suppression parallels the loss of sensitivity and frequency tuning due to outer hair cell dysfunction, the present findings suggest that mechanical two-tone suppression arises from an interaction between the outer hair cells and the basilar membrane.

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