Auditory Distortions: Origins and Functions

Avan, Paul; Büki, Béla; Petit, Christine

doi:10.1152/physrev.00029.2012

Cited by 93 publications

(69 citation statements)

References 307 publications

(487 reference statements)

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“…The characteristics of distortion product otoacoustic emissions (DPOAEs), i.e., distortion products (DPs) measured in the ear canal, have been thoroughly described in the literature (e.g., Probst et al 1991;Avan et al 2013). In contrast, considerably less is known concerning the properties of intracochlear DPs (iDPs) at the DP frequency place (f dp ) on the basilar membrane (BM).…”

Section: Introductionmentioning

confidence: 99%

Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay

Martin

Stagner

Dong

et al. 2016

JARO

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The behavior of intracochlear distortion products (iDPs) was inferred by interacting a probe tone (f 3 ) with the iDP of interest to produce a Bsecondaryd istortion product otoacoustic emission termed DPOAE 2ry . Measures of the DPOAE 2ry were then used to deduce the properties of the iDP. This approach was used in alert rabbits and anesthetized gerbils to compare ear-canal 2f 1 -f 2 and 2f 2 -f 1 DPOAE f 2 /f 1 ratio functions, level/phase (L/P) maps, and interferenceresponse areas (IRAs) to their simultaneously collected DPOAE 2ry counterparts. These same measures were also collected in a human volunteer to demonstrate similarities with their laboratory animal counterparts and their potential applicability to humans. Results showed that DPOAEs and inferred iDPs evidenced distinct behaviors and properties. That is, DPOAE ratio functions elicited by low-level primaries peaked around an f 2 /f 1 = 1.21 or 1.25, depending on species, while the corresponding inferred iDP ratio functions peaked at f 2 /f 1 ratios of~1. Additionally, L/ P maps showed rapid phase variation with DPOAE frequency (f dp ) for the narrow-ratio 2f 1 -f 2 and all 2f 2 -f 1 DPOAEs, while the corresponding DPOAE 2ry measures evidenced relatively constant phases. Common features of narrow-ratio DPOAE IRAs, such as large enhancements for interference tones (ITs) presented above f 2 , were not present in DPOAE 2ry IRAs. Finally, based on prior experiments in gerbils, the behavior of the iDP directly measured in intracochlear pressure was compared to the iDP inferred from the DPOAE 2ry and found to be similar. Together, these findings are consistent with the notion that under certain conditions, ear-canal DPOAEs provide poor representations of iDPs and thus support a Bbeamforming^hypothe-sis. According to this concept, distributed emission components directed toward the ear canal from the f 2 and basal to f 2 regions can be of differing phases and thus cancel, while these same components directed toward f dp add in phase.

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Section: Introductionmentioning

confidence: 99%

Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay

Martin

Stagner

Dong

et al. 2016

JARO

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“…IHCs are the genuine sensory cells that transduce the sound stimuli into electrical signals in the primary auditory neurons. OHCs are mechanical effectors that amplify the sound-evoked movements of the cochlear partition, sharpen its frequency selectivity, and produce waveform distortions (1,2). A pure-tone stimulus entering the cochlea elicits a traveling wave that propagates along the BM from the cochlear base toward its apex, increasing in amplitude until it peaks at a characteristic place, where the mechanical properties of the cochlea are best tuned to the stimulus frequency.…”

mentioning

confidence: 99%

“…In the normal cochlea, in response to a pure tone, a locally restricted OHC-driven active process enhances and sharpens the peak of the traveling wave, particularly at low stimulus levels. This causes compressive growth of the wave amplitude at the place tuned to its frequency (1,2).…”

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confidence: 99%

An unusually powerful mode of low-frequency sound interference due to defective hair bundles of the auditory outer hair cells

Kamiya

Michel

Giraudet

et al. 2014

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

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A detrimental perceptive consequence of damaged auditory sensory hair cells consists in a pronounced masking effect exerted by low-frequency sounds, thought to occur when auditory threshold elevation substantially exceeds 40 dB. Here, we identified the submembrane scaffold protein Nherf1 as a hair-bundle component of the differentiating outer hair cells (OHCs). Nherf1 −/− mice displayed OHC hair-bundle shape anomalies in the mid and basal cochlea, normally tuned to mid-and high-frequency tones, and mild (22-35 dB) hearing-threshold elevations restricted to midhigh sound frequencies. This mild decrease in hearing sensitivity was, however, discordant with almost nonresponding OHCs at the cochlear base as assessed by distortion-product otoacoustic emissions and cochlear microphonic potentials. Moreover, unlike wild-type mice, responses of Nherf1 −/− mice to high-frequency (20-40 kHz) test tones were not masked by tones of neighboring frequencies. Instead, efficient maskers were characterized by their frequencies up to two octaves below the probe-tone frequency, unusually low intensities up to 25 dB below probe-tone level, and growth-ofmasker slope (2.2 dB/dB) reflecting their compressive amplification. Together, these properties do not fit the current acknowledged features of a hypersensitivity of the basal cochlea to lower frequencies, but rather suggest a previously unidentified mechanism. Low-frequency maskers, we propose, may interact within the unaffected cochlear apical region with midhigh frequency sounds propagated there via a mode possibly using the persistent contact of misshaped OHC hair bundles with the tectorial membrane. Our findings thus reveal a source of misleading interpretations of hearing thresholds and of hypervulnerability to low-frequency sound interference.off-frequency detection | Usher syndrome | hearing impairment | Nherf2 | tail hypersensitivity M ammalian hearing displays remarkable sensitivity, fine temporal acuity, and exquisite frequency selectivity, which contribute to auditory scene analysis and speech intelligibility. The first steps of sound processing, i.e., sound wave detection and neuronal encoding in the cochlea, are performed by two populations of hair cells, the inner hair cells (IHCs) and the outer hair cells (OHCs). These cells are sandwiched between the underlying basilar membrane (BM) and the overlying tectorial membrane (TM) (SI Appendix, Fig. S1A). IHCs are the genuine sensory cells that transduce the sound stimuli into electrical signals in the primary auditory neurons. OHCs are mechanical effectors that amplify the sound-evoked movements of the cochlear partition, sharpen its frequency selectivity, and produce waveform distortions (1, 2). A pure-tone stimulus entering the cochlea elicits a traveling wave that propagates along the BM from the cochlear base toward its apex, increasing in amplitude until it peaks at a characteristic place, where the mechanical properties of the cochlea are best tuned to the stimulus frequency. Beyond this characteristic place, the ampl...

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“…Nonetheless prominent symptoms of the condition are a "feeling of fullness", a fluctuating hearing loss and a low-frequency tinnitus. They may have many origins, yet are consistent with the existence of a mechanical bias acting on the basilar membrane [7] thereby producing asymmetric distortion of the cochlear microphonic plus concomitant changes in distortion products measured in the ear canal [1].…”

Section: Introductionmentioning

confidence: 59%

“…Hi-pass filtering by the helicotrema has traditionally been used to explain this. However, this is not true of Meniere's patients [1]. Our object is therefore to discover not just what causes failure of homeostasis, but what is responsible for it in the first place.…”

Section: Discussionmentioning

confidence: 95%

Direct testing of the biasing effect of manipulations of endolymphatic pressure on cochlear mechanical function

LePage¹,

Avan²

2015

AIP Conference Proceedings

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Abstract. The history of cochlear mechanical investigations has been carried out in two largely separate sets of endeavours; those interested in auditory processing in animal models and those interested in the origin of adverse vestibular symptoms in humans. In respect of the first, mechanical vibratory data is considered pathological and not representative of pristine behaviour if it departs from the reigning model of sharp tuning and high hearing sensitivity. Conversely, when the description of the pathological behaviour is the focus, fluid movements responsible for hearing loss and vestibular symptoms dominate. Yet both extensive sets of data possess a common factor now being reconsidered for its potential to shed light on the mechanisms in general. The common factor is a mechanical bias -the departure of cochlear epithelial membranes from their usual resting position. In both cases the bias modulates hearing sensitivity and distorts tuning characteristics. Indeed several early sets of guinea pig mechanical data were dismissed as "pathological" when in hindsight, the primary effect influencing the data was not loss of outer hair cell function per se, but a mechanical bias unknowingly introduced in process of making the measurement. Such biases in the displacement of the basilar membrane from its position are common, and may be caused by low-frequency sounds (topically including infrasound) or by variations in fluid volume in the chambers particularly applying the case of endolymphatic hydrops. Most biases are quantified in terms of visualisation of fluid volume change, electric potential changes and otoacoustic emissions. Notably many previous studies have also searched for raised pressures with negative results. Yet these repeated findings are contrary to the widespread notion that, at least when homeostasis is lost, it is a rise in endolymphatic pressure which is responsible for membrane rupture and Meniere's attacks. This current investigation in Mongolian gerbils is aimed at quantifying hydrostatic pressures in cochlear chambers by direct measurement using a null-flow micropipette pressure measurement system, while simultaneously quantifying electric potentials and distortion products to provide indirect measures of displacement bias and hair cell integrity. We now suspect that during any experiment obtaining of good pressure seals is critical. Secondary penetrations, such as occur in neural recordings, are contra-indicated. When we address the issue of seals we see raised pressures in response to manipulations known to disturb homeostasis, viz. diuretics and hypoxia.

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Auditory Distortions: Origins and Functions

Cited by 93 publications

References 307 publications

Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay

Comparing Distortion Product Otoacoustic Emissions to Intracochlear Distortion Products Inferred from a Noninvasive Assay

An unusually powerful mode of low-frequency sound interference due to defective hair bundles of the auditory outer hair cells

Direct testing of the biasing effect of manipulations of endolymphatic pressure on cochlear mechanical function

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