Forward and reverse transfer functions of the middle ear based on pressure and velocity DPOAEs with implications for differential hearing diagnosis

Dalhoff, Ernst; Ţurcanu, Diana; Gummer, Anthony W.

doi:10.1016/j.heares.2011.04.015

Cited by 15 publications

(15 citation statements)

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“…Umbo velocity and EC pressure were used to estimate the FTF and RTF in guinea pig by Dalhoff et al (2011), and in general, the RTF was greater than the FTF, similar to our results. In addition, they observed a notch in the RTF; while the DPOAE was relatively smooth with frequency, the umbo velocity had a deep notch at ∼8 kHz.…”

Section: Discussionsupporting

confidence: 85%

“…All of these studies showed gain and delay in forward transmission (from the EC to the stapes or scala vestibuli (SV) close to the stapes) and loss and delay in backward transmission (from the stapes or SV to the EC). In related work, Dalhoff et al (2011) compared DPs on the umbo and EC for diagnosis of hearing problems. Our previous results comparing forward and reverse transmission in gerbil provided background to the present study, with an example shown in Figure 1.…”

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confidence: 99%

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Reverse Transmission along the Ossicular Chain in Gerbil

Dong

Decraemer

Olson

2012

JARO

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In a healthy cochlea stimulated with two tones f 1 and f 2 , combination tones are generated by the cochlea's active process and its associated nonlinearity. These distortion tones travel "in reverse" through the middle ear. They can be detected with a sensitive microphone in the ear canal (EC) and are known as distortion product otoacoustic emissions. Comparisons of ossicular velocity and EC pressure responses at distortion product frequencies allowed us to evaluate the middle ear transmission in the reverse direction along the ossicular chain. In the current study, the gerbil ear was stimulated with two equal-intensity tones with fixed f 2 /f 1 ratio of 1.05 or 1.25. The middle ear ossicles were accessed through an opening of the pars flaccida, and their motion was measured in the direction in line with the stapes pistonlike motion using a laser interferometer. When referencing the ossicular motion to EC pressure, an additional amplitude loss was found in reverse transmission compared to the gain in forward transmission, similar to previous findings relating intracochlear and EC pressure. In contrast, sound transmission along the ossicular chain was quite similar in forward and reverse directions. The difference in middle ear transmission in forward and reverse directions is most likely due to the different load impedances-the cochlea in forward transmission and the EC in reverse transmission.Keywords: middle ear, ossicles, middle ear gain, otoacoustic emissions Since Kemp's (1978) discovery of otoacoustic emissions (OAEs), OAEs have been used for probing the active process of the cochlea. The middle ear is responsible for transmitting sound in and out of the cochlea, thus it shapes the OAE as well as the primaries. Consequently, it is important to understand how the middle ear transmits sound reversely, from the cochlea to the ear canal (EC). In forward sound transmission, the external and middle ear convey environmental sound to the inner ear, the cochlea. The middle ear plays the role of an impedance matcher, coupling the relatively low acoustic impedance of the EC to the much higher input impedance of the cochlea. Sound pressure drives the tympanic membrane (TM), which induces vibration along the ossicular chain, composed of the malleus, incus, and stapes. The stapes vibration produces an intracochlear pressure that is larger than the input pressure at the TM, which is characterized as "middle-ear pressure gain." This pressure gain through the middle ear has been studied in cat (Decory et al. 1990;Nedzelnitsky 1980), chinchilla (Decory et al. 1990;Slama et al. 2010), gerbil (de La Rochefoucauld et al. 2008Dong and Olson 2006;Olson 1998Olson , 2001), guinea pig (Dancer and Franke 1980;Decory et al. 1990;Magnan et al. 1997), and human temporal bone (Aibara et al. 2001;Nakejima et al. 2008;Puria 2003a;Puria et al. 1997). In addition to the pressure gain, the more recent studies also document a delay associated with the transmission between the EC and cochlea.The effect of the middle ear on OAEs has been explo...

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Section: Discussionsupporting

confidence: 85%

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confidence: 99%

Reverse Transmission along the Ossicular Chain in Gerbil

Dong

Decraemer

Olson

2012

JARO

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“…The same problem occurred for the hybrid model investigated by Dalhoff et al, 10 where it is discussed in detail. In our model as well, it could not be solved by changing the resistive component of the eardrum.…”

Section: A String With Rigid Supportmentioning

confidence: 64%

“…Recently, this model has been adapted to study a reverse transfer function of the tympanic membrane of the guinea pig. 10 The problem with that model is that the transmission line seems to be justified merely by empirical findings. In particular, one of its deficiencies is that all acoustical input to the transmission line, i.e., the sound pressure in front of the tympanic membrane, undergoes the same delay, whereas in reality, there should be different contributions whose delay depends on whether the sound pressure acts on the periphery or onto the center of the membrane.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the eardrum as a string with distributed force

Goll

Dalhoff

2011

The Journal of the Acoustical Society of America

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In this paper, an analytical model of the tympanic membrane is introduced where the two-dimensional tympanic membrane is reduced to a one-dimensional string. It is intended to bridge the gap between lumped-element models and finite-element models. In contrast to known lumped-element models, the model takes the distributed effect of the sound field on the tympanic membrane into account. Compared to finite-element models, it retains the advantage of a low number of parameters. The model is adjusted to forward and reverse transfer functions of the guinea-pig middle ear. Although the fitting to experimental data is not perfect, important conclusions can be drawn. For instance, the model shows that the delay of surface waves on the tympanic membrane can be different from the signal transmission delay of the tympanic membrane. In a similar vein, the standing wave ratio on the tympanic membrane and within the ear canal can considerably differ. Further, the model shows that even in a low-loss tympanic membrane the effective area, which commonly is associated with the transformer ratio in a lumped-element and some hybrid circuit models, not only is frequency-dependent, but also different for forward and reverse transduction.

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