Reflections on the role of a traveling wave along the basilar membrane in view of clinical and experimental findings

Sohmer, Haim

doi:10.1007/s00405-014-3045-z

Cited by 11 publications

(9 citation statements)

References 40 publications

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“…It is often argued that two compliant windows in the inner ear is required to evoke a BC response (Sohmer, 2014). For occlusion of either the RW or the OW, the effect on the BC thresholds was predicted similar by the model.…”

Section: Discussionmentioning

confidence: 87%

Inner ear contribution to bone conduction hearing in the human

Stenfelt

2015

Hearing Research

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Bone conduction (BC) hearing relies on sound vibration transmission in the skull bone.Several clinical findings indicate that in the human, the skull vibration of the inner ear dominates the response for BC sound. Two phenomena transform the vibrations of the skull surrounding the inner ear to an excitation of the basilar membrane, (1) inertia of the inner ear fluid and (2) compression and expansion of the inner ear space. The relative importance of these two contributors were investigated using an impedance lumped element model. By dividing the motion of the inner ear boundary in common and differential motion it was found that the common motion dominated at frequencies below 7 kHz but above this frequency differential motion was greatest. When these motions were used to excite the model it was found that for the normal ear, the fluid inertia response was up to 20 dB greater than the compression response. This changed in the pathological ear where, for example, otosclerosis of the stapes depressed the fluid inertia response and improved the compression response so that inner ear compression dominated BC hearing at frequencies above 400 Hz.The model was also able to predict experimental and clinical findings of BC sensitivity in the literature, for example the so called Carhart notch in otosclerosis, increased BC sensitivity in superior semicircular canal dehiscence, and altered BC sensitivity following a vestibular fenestration and RW atresia.

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Section: Discussionmentioning

confidence: 87%

Inner ear contribution to bone conduction hearing in the human

Stenfelt

2015

Hearing Research

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“…Therefore, it is likely that threshold intensity STC stimulation does not lead to vibrations of the skull bone (temporal/petrous bone), which are required for BC stimulation by inducing vibrations of the middle ear ossicles, the two windows, and of the cochlea (Tonndorf, 1968;Stenfelt and Goode, 2005). In addition, recent experiments in this laboratory have shown no change in STC and BC thresholds after immobilization and discontinuity of the middle ear ossicles and fixation of the two windows (Perez et al, 2011a,b;2014). Such immobilization, and discontinuity and fixation, eliminating middle ear and window involvement in BC mechanisms, would have been expected to lead to some degree of threshold elevation if skull vibrations (temporal/petrous bone) were involved during threshold BC stimulation.…”

Section: Introductionmentioning

confidence: 99%

Air Conduction, Bone Conduction, and Soft Tissue Conduction Audiograms in Normal Hearing and Simulated Hearing Losses

Adelman¹,

Cohen²,

Regev-Cohen³

et al. 2015

J Am Acad Audiol

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These results, which show a similar threshold shift for STC and for BC as a result of these simulations, together with additional clinical and laboratory findings, provide evidence that BC thresholds likely represent the threshold of the nonosseous BC (STC) component of multicomponent BC at the BC stimulation site, and thereby succeed in clinical practice to contribute to the differential diagnosis. This also provides evidence that STC (nonosseous BC) stimulation at low intensities probably does not involve components of the middle ear, represents true cochlear function, and therefore can also contribute to a differential diagnosis (e.g., in situations where the clinical bone vibrator cannot be applied to the mastoid or forehead with a 5 N force, such as in severe skull fracture).

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“…[243132] These findings, as well as clinical observations showing preserved BC thresholds in the absence of two mobile windows in the inner ear,[3334] support the existence of a mechanism that is different from AC and osseous BC. [35]…”

Section: Discussionmentioning

confidence: 99%

Soft tissue conduction as a possible contributor to the limited attenuation provided by hearing protection devices

Chordekar

Adelman

Sohmer³

et al. 2016

Noise Health

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Context:Damage to the auditory system by loud sounds can be avoided by hearing protection devices (HPDs) such as earmuffs, earplugs, or both for maximum attenuation. However, the attenuation can be limited by air conduction (AC) leakage around the earplugs and earmuffs by the occlusion effect (OE) and by skull vibrations initiating bone conduction (BC).Aims:To assess maximum attenuation by HPDs and possible flanking pathways to the inner ear.Subjects and Methods:AC attenuation and resulting thresholds were assessed using the real ear attenuation at threshold (REAT) procedure on 15 normal-hearing participants in four free-field conditions: (a) unprotected ears, (b) ears covered with earmuffs, (c) ears blocked with deeply inserted customized earplugs, and (d) ears blocked with both earplugs and earmuffs. BC thresholds were assessed with and without earplugs to assess the OE.Results:Addition of earmuffs to earplugs did not cause significantly greater attenuation than earplugs alone, confirming minimal AC leakage through the external meatus and the absence of the OE. Maximum REATs ranged between 40 and 46 dB, leading to thresholds of 46–54 dB HL. Furthermore, calculation of the acoustic impedance mismatch between air and bone predicted at least 60 dB attenuation of BC.Conclusion:Results do not support the notion that skull vibrations (BC) contributed to the limited attenuation provided by traditional HPDs. An alternative explanation, supported by experimental evidence, suggests transmission of sound to inner ear via non-osseous pathways such as skin, soft tissues, and fluid. Because the acoustic impedance mismatch between air and soft tissues is smaller than that between air and bone, air-borne sounds would be transmitted to soft tissues more effectively than to bone, and therefore less attenuation is expected through soft tissue sound conduction. This can contribute to the limited attenuation provided by traditional HPDs. The present study has practical implications for hearing conservation protocols.

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Reflections on the role of a traveling wave along the basilar membrane in view of clinical and experimental findings

Cited by 11 publications

References 40 publications

Inner ear contribution to bone conduction hearing in the human

Inner ear contribution to bone conduction hearing in the human

Air Conduction, Bone Conduction, and Soft Tissue Conduction Audiograms in Normal Hearing and Simulated Hearing Losses

Soft tissue conduction as a possible contributor to the limited attenuation provided by hearing protection devices

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