The Remarkable Outer Hair Cell: Proceedings of a Symposium in Honour of W. E. Brownell

Ashmore, Jonathan; Oghalai, John S.; Dewey, James B.; Olson, Elizabeth S.; Strimbu, C. Elliott; Wang, Yi; Shera, Christopher A.; Altoè, Alessandro; Abdala, Carolina; Elgoyhen, Ana BelÃ©n; Eatock, Ruth Anne; Raphael, Robert M.

doi:10.1007/s10162-022-00852-4

Cited by 3 publications

(2 citation statements)

References 77 publications

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“…This is a highly relevant question that we are exploring at present with other studies. In emerging work, however, we have observed distinct patterns in OAE level reduction from ears with noise-induced hearing loss versus presbyacusis (Abdala et al 2023). And here, we note that even in EH ears with no elevated thresholds, OAEs were abnormally reduced.…”

Section: A Signature Oae Profile For Eh?mentioning

confidence: 37%

“…The joint-OAE profile may be helpful in the diagnosis and monitoring of EH. While measuring reflection (stimulus-frequency [SF]) and distortion (DP) OAEs in an initial pilot subject with diagnosed EH, we observed an interesting pattern: DPOAEs were extremely low level or non-measurable at low frequencies, while SFOAEs were near-normal at these same frequencies (Abdala et al 2020; Ashmore et al 2023). Previous work in guinea pigs supports this result.…”

Section: Introductionmentioning

confidence: 97%

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Characterizing a Joint Reflection-Distortion OAE Profile in Humans With Endolymphatic Hydrops

2023

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Objectives: Endolymphatic hydrops (EH), a hallmark of Meniere disease, is an inner-ear disorder where the membranes bounding the scala media are distended outward due to an abnormally increased volume of endolymph. In this study, we characterize the joint-otoacoustic emission (OAE) profile, a results profile including both distortion- and reflection-class emissions from the same ear, in individuals with EH and speculate on its potential utility in clinical assessment and monitoring. Design: Subjects were 16 adults with diagnosed EH and 18 adults with normal hearing (N) matched for age. Both the cubic distortion product (DP) OAE, a distortion-type emission, and the stimulus-frequency (SF) OAE, a reflection-type emission, were measured and analyzed as a joint OAE profile. OAE level, level growth (input/output functions), and phase-gradient delays were measured at frequencies corresponding to the apical half of the human cochlea and compared between groups. Results: Normal hearers and individuals with EH shared some common OAE patterns, such as the reflection emissions being generally higher in level than distortion emissions and showing more linear growth than the more strongly compressed distortion emissions. However, significant differences were noted between the EH and N groups as well. OAE source strength (a metric based on OAE amplitude re: stimulus level) was significantly reduced, as was OAE level, at low frequencies in the EH group. These reductions were more marked for distortion than reflection emissions. Furthermore, two significant changes in the configuration of OAE input/output functions were observed in ears with EH: a steepened growth slope for reflection emissions and an elevated compression knee for distortion emissions. SFOAE phase-gradient delays at 40 dB forward-pressure level were slightly shorter in the group with EH compared with the normal group. Conclusions: The underlying pathology associated with EH impacts the generation of both emission types, reflection and distortion, as shown by significant group differences in OAE level, growth, and delay. However, hydrops impacts reflection and distortion emissions differently. Most notably, DPOAEs were more reduced by EH than were SFOAEs, suggesting that pathologies associated with the hydropic state do not act identically on the generation of nonlinear distortion at the hair bundle and intracochlear reflection emissions near the peak of the traveling wave. This differential effect underscores the value of applying a joint OAE approach to access both intracochlear generation processes concurrently.

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Section: A Signature Oae Profile For Eh?mentioning

confidence: 37%

Section: Introductionmentioning

confidence: 97%

Characterizing a Joint Reflection-Distortion OAE Profile in Humans With Endolymphatic Hydrops

2023

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The Long Outer-Hair-Cell RC Time Constant: A Feature, Not a Bug, of the Mammalian Cochlea

Altoè

Shera

2023

JARO

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The cochlea of the mammalian inner ear includes an active, hydromechanical amplifier thought to arise via the piezoelectric action of the outer hair cells (OHCs). A classic problem of cochlear biophysics is that the RC (resistance-capacitance) time constant of the hair-cell membrane appears inconveniently long, producing an effective cut-off frequency much lower than that of most audible sounds. The long RC time constant implies that the OHC receptor potential—and hence its electromotile response—decreases by roughly two orders of magnitude over the frequency range of mammalian hearing, casting doubt on the hypothesized role of cycle-by-cycle OHC-based amplification in mammalian hearing. Here, we review published data and basic physics to show that the “RC problem” has been magnified by viewing it through the wrong lens. Our analysis finds no appreciable mismatch between the expected magnitude of high-frequency electromotility and the sound-evoked displacements of the organ of Corti. Rather than precluding significant OHC-based boosts to auditory sensitivity, the long RC time constant appears beneficial for hearing, reducing the effects of internal noise and distortion while increasing the fidelity of cochlear amplification.

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Swept Along: Measuring Otoacoustic Emissions Using Continuously Varying Stimuli

Shera

2024

JARO

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At the 2004 Midwinter Meeting of the Association for Research in Otolaryngology, Glenis Long and her colleagues introduced a method for measuring distortion-product otoacoustic emissions (DPOAEs) using primary-tone stimuli whose instantaneous frequencies vary continuously with time. In contrast to standard OAE measurement methods, in which emissions are measured in the sinusoidal steady state using discrete tones of well-defined frequency, the swept-tone method sweeps across frequency, often at rates exceeding 1 oct/s. The resulting response waveforms are then analyzed using an appropriate filter (e.g., by least-squares fitting). Although introduced as a convenient way of studying DPOAE fine structure by separating the total OAE into distortion and reflection components, the swept-tone method has since been extended to stimulus-frequency emissions and has proved an efficient and valuable tool for probing cochlear mechanics. One day—a long time coming—swept tones may even find their way into the audiology clinic.

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The Remarkable Outer Hair Cell: Proceedings of a Symposium in Honour of W. E. Brownell

Cited by 3 publications

References 77 publications

Characterizing a Joint Reflection-Distortion OAE Profile in Humans With Endolymphatic Hydrops

Characterizing a Joint Reflection-Distortion OAE Profile in Humans With Endolymphatic Hydrops

The Long Outer-Hair-Cell RC Time Constant: A Feature, Not a Bug, of the Mammalian Cochlea

Swept Along: Measuring Otoacoustic Emissions Using Continuously Varying Stimuli

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