Inverted direction of wave propagation (IDWP) in the cochlea

Boer, E. de; Zheng, Jie; Porsov, Edward; Nuttall, Alfred L.

doi:10.1121/1.2828064

Cited by 27 publications

(37 citation statements)

References 33 publications

(31 reference statements)

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“…The modeling studies reported here address the counterintuitive experimental finding (Ren, 2002;He et al, 2007He et al, , 2008He et al, , 2010de Boer and Nuttall, 2008) that the spatial phase profile of the DP traveling wave along the BM has a negative phase slope (NPS), implying that DP waves are traveling predominantly into the cochlea rather than out of it. The explanation proposed by Ren is that backwardtraveling waves on the BM are small (or nonexistent) because the DP energy escapes from the cochlea via an alternative propagation mode (namely fast compressional waves in the fluid) that, unlike the transpartition pressure wave, couples only weakly (if at all) to the motion of the BM.…”

Section: Discussionmentioning

confidence: 99%

“…The basic assumption of de Boer et al (2008) was that a backward wave, propagating from the DP generation place, either x 2 or x DP , to the cochlear base should have a PPS at a fixed place, x 0 . We have seen that this assumption can be justified by the arguments leading to Eq.…”

Section: A Frequency-domain Analytical Estimatesmentioning

confidence: 99%

“…Recent measurements of the amplitude and phase of the BM vibration in gerbils at the DP frequency at different cochlear places (He et al, 2007) have been interpreted as a demonstration that there is no backward-traveling wave at the DP frequency. More recently, de Boer et al (2008) performed a slightly different experiment on guinea pigs, in which the phase of the BM vibration at the DP frequency was recorded as a function of the varying primary frequency f 2 , at constant primary frequency ratio f 2 /f 1 . The BM vibration was measured at a fixed cochlear place x(f 0 ) (x 0 , in the following), which, for f 0 >f 2 is basal to x 2 .…”

Section: Introductionmentioning

confidence: 99%

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Distortion products and backward-traveling waves in nonlinear active models of the cochlea

Sisto

Moleti

Botti

et al. 2011

The Journal of the Acoustical Society of America

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This study explores the phenomenology of distortion products in nonlinear cochlear models, predicting their amplitude and phase along the basilar membrane. The existence of a backward-traveling wave at the distortion-product frequency, which has been recently questioned by experiments measuring the phase of basilar-membrane vibration, is discussed. The effect of different modeling choices is analyzed, including feed-forward asymmetry, micromechanical roughness, and breaking of scaling symmetry. The experimentally observed negative slope of basilar-membrane phase is predicted by numerical simulations of nonlinear cochlear models under a wide range of parameters and modeling choices. In active models, positive phase slopes are predicted by the quasi-linear analytical computations and by the fully nonlinear numerical simulations only if the distortionproduct sources are localized apical to the observation point and if the stapes reflectivity is unrealistically small. The results of this study predict a negative phase slope whenever the source is distributed over a reasonably wide cochlear region and/or a reasonably high stapes reflectivity is assumed. Therefore, the above-mentioned experiments do not contradict "classical" models of cochlear mechanics and of distortion-product generation.

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Section: Discussionmentioning

confidence: 99%

Section: A Frequency-domain Analytical Estimatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distortion products and backward-traveling waves in nonlinear active models of the cochlea

Sisto

Moleti

Botti

et al. 2011

The Journal of the Acoustical Society of America

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“…One reason is that most of the studies have focused on frequency regions around the BF, which seem to be dominated by the local/forwardtraveling component, especially for the 2f 1 − f 2 [see DP evoked by 50 dB SPL, blue lines in Fig. 2 and, i.e., Ren (2004) andde Boer et al (2008)]. When an effort was made to make the comparison between the DPs measured at two longitudinal BM locations, the ∼200 μm separation of two locations appeared to not be large enough to resolve the non-local reversetraveling component when considering that the generation region broadens with increasing primary levels (He et al 2007).…”

Section: Discussionmentioning

confidence: 99%

“…The characteristics of DPs are complex when measured at one location in the cochlea and appear to include both local and non-local or forward-and reverse-traveling components (de Boer 2007;de Boer et al 2007;Rhode 2007;Shera et al 2007;de Boer et al 2008;Dong andOlson 2008, 2010). Therefore, recognizing different components of the measured intracochlear DP is an important starting point.…”

Section: Propagation Of Dps In the Cochleamentioning

confidence: 99%

Simultaneous Intracochlear Pressure Measurements from Two Cochlear Locations: Propagation of Distortion Products in Gerbil

Dong

2016

JARO

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Sound energy propagates in the cochlea through a forward-traveling or slow wave supported by the cochlear partition and fluid inertia. Additionally, cochlear models support traveling wave propagation in the reverse direction as the expected mechanism for conveying otoacoustic emissions out of the cochlea. Recently, however, this hypothesis has been questioned, casting doubt on the process by which otoacoustic emissions travel back out through the cochlea. The proposed alternative reverse travel path for emissions is directly through the fluids of the cochlea as a compression pressure in the form of a fast wave. In the present study, a custom-made micropressure sensor was used in vivo in the gerbil cochlea to map two-tone-evoked pressure responses at distinct longitudinal and vertical locations in both the scala tympani and scala vestibuli. Analyses of the magnitude and phase of intracochlear pressure responses at the primary tone and distortion product frequencies were used to distinguish between fast and slow waves in both the forward-and reverse-propagation directions. Results demonstrated that distortion products may travel in both forward and reverse directions postgeneration and the existence of both traveling and compression waves. The forward-traveling component appeared to duplicate the process of any external tone, tuned to the local characteristic-frequency place, as it increased compressively and nonlinearly with primary-tone levels. A compression wave was evidenced at frequencies above the cutoff of the recording site. In the opposite direction, a reversetraveling wave played the major role in driving the stapes reversely and contributed to the distortion product otoacoustic emission. The compression wave may also play a role in reverse propagation when distortion products are generated at a region close to the stapes.

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Optimal Scale-Invariant Wavelet Representation and Filtering of Human Otoacoustic Emissions

Moleti

2024

JARO

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Otoacoustic emissions (OAEs) are generated in the cochlea and recorded in the ear canal either as a time domain waveform or as a collection of complex responses to tones in the frequency domain (Probst et al. J Account Soc Am 89:2027–2067, 1991). They are typically represented either in their original acquisition domain or in its Fourier-conjugated domain. Round-trip excursions to the conjugated domain are often used to perform filtering operations in the computationally simplest way, exploiting the convolution theorem. OAE signals consist of the superposition of backward waves generated in different cochlear regions by different generation mechanisms, over a wide frequency range. The cochlear scaling symmetry (cochlear physics is the same at all frequency scales), which approximately holds in the human cochlea, leaves its fingerprints in the mathematical properties of OAE signals. According to a generally accepted taxonomy (Sher and Guinan Jr, J Acoust Soc Am 105:782–798, 1999), OAEs are generated either by wave-fixed sources, moving with frequency according with the cochlear scaling (as in nonlinear distortion) or by place-fixed sources (as in coherent reflection by roughness). If scaling symmetry holds, the two generation mechanisms yield OAEs with different phase gradient delay: almost null for wave-fixed sources, and long (and scaling as 1/f) for place-fixed sources. Thus, the most effective representation of OAE signals is often that respecting the cochlear scale-invariance, such as the time-frequency domain representation provided by the wavelet transform. In the time-frequency domain, the elaborate spectra or waveforms yielded by the superposition of OAE components from different generation mechanisms assume a much clearer 2-D pattern, with each component localized in a specific and predictable region. The wavelet representation of OAE signals is optimal both for visualization purposes and for designing filters that effectively separate different OAE components, improving both the specificity and the sensitivity of OAE-based applications. Indeed, different OAE components have different physiological meanings, and filtering dramatically improves the signal-to-noise ratio.

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Inverted direction of wave propagation (IDWP) in the cochlea

Cited by 27 publications

References 33 publications

Distortion products and backward-traveling waves in nonlinear active models of the cochlea

Distortion products and backward-traveling waves in nonlinear active models of the cochlea

Simultaneous Intracochlear Pressure Measurements from Two Cochlear Locations: Propagation of Distortion Products in Gerbil

Optimal Scale-Invariant Wavelet Representation and Filtering of Human Otoacoustic Emissions

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