Middle-ear velocity transfer function, cochlear input immittance, and middle-ear efficiency in chinchilla

Abstract

The transfer function H(V) between stapes velocity V(S) and sound pressure near the tympanic membrane P(TM) is a descriptor of sound transmission through the middle ear (ME). The ME power transmission efficiency (MEE), the ratio of sound power entering the cochlea to power entering the middle ear, was computed from H(V) measured in seven chinchilla ears and previously reported measurements of ME input admittance Y(TM) and ME pressure gain G(MEP) [Ravicz and Rosowski, J. Acoust. Soc. Am. 132, 2437-2454 (2012); J. Acoust. Soc. Am. 133, 2208-2223 (2013)] in the same ears. The ME was open, and a pressure sensor was inserted into the cochlear vestibule for most measurements. The cochlear input admittance Y(C) computed from H(V) and G(MEP) is controlled by a combination of mass and resistance and is consistent with a minimum-phase system up to 27 kHz. The real part Re{Y(C)}, which relates cochlear sound power to inner-ear sound pressure, decreased gradually with frequency up to 25 kHz and more rapidly above that. MEE was about 0.5 between 0.1 and 8 kHz, higher than previous estimates in this species, and decreased sharply at higher frequencies.

Stapes Vibration in the Chinchilla Middle Ear: Relation to Behavioral and Auditory-Nerve Thresholds

“…5 and 6 of )), one might expect that the wider bandwidth of the present stapes-velocity measurements (Fig. 6A) should be associated with shorter phase delays than in previous measurements Ravicz and Rosowski 2013b). However, the present phase delays are longer than those of previous measurements (Fig.…”

“…[Note that at least for frequencies 150-2000 Hz at the base of the chinchilla cochlea, basilar-membrane displacement is proportional to, and in phase with, velocity (rather than displacement) of the stapes ).] Indeed, as Figure 7 shows, the stapes-velocity and the modified neural-sensitivity curves are similar over nearly a two-decade frequency range (200 Hz-14 kHz), mostly differing in that the neural curve shows no evidence of a counterpart to the prominent 3-kHz notch in the stapes-velocity curve, which is also evident in other middle-ear measurements Ravicz and Rosowski 2013b)). The absence of a notch in the average neural data may be due to individual variations in the sizes of bulla openings.…”

Estimation of Round-Trip Outer-Middle Ear Gain Using DPOAEs

“…Investigating how the outer and middle ear shape the transmitted sound would benefit OAEs as a research and diagnostic tool. Efforts to determine sound transmission characteristics of the middle ear invasively were made on living human ears (Huber et al 2001;Chien et al 2009), human cadaveric temporal bones (Puria and Rosowski 1996;Puria et al 1997;Voss et al 2000;Aibara et al 2001;Puria 2003;Nakajima et al 2009), gerbils (Dong and Olson 2006;Ravicz et al 2008;Dong et al 2012), cats (Voss and Shera 2004), chinchillas (Songer and Rosowski 2007;Ravicz et al 2010;Ravicz and Rosowski 2013), and guinea pigs (Nuttall 1974;Magnan et al 1997). Huber et al (2001) measured stapes displacement during surgery in patients who were going under cochlear implantation.…”

Non-invasive estimation of middle-ear input impedance and efficiency

“…(16) (replacing Z EC_M with Z EC and Z ED_M with Z ED ) for Z ED . From the ME and cochlear model, ME efficiency (g ME ; Rosowski et al, 1986;Rosowski, 1991;Ravicz and Rosowski, 2013) was calculated as…”

“…Knowing Z ED , as well as A and jRj 2 , may still not take full advantage of the diagnostic power of ear-canal measurements without some additional measure describing the efficiency of the ME in delivering sound to the cochlea (i.e., ME efficiency, Rosowski et al, 1986;Rosowski, 1991;Ravicz and Rosowski, 2013). For instance, jRj 2 in ears with large eardrum perforations can approximate normal ears despite the likely presence of a conductive hearing loss (Voss et al, 2001a;Voss et al, 2012;Mehta et al, 2006).…”