Cochlear mechanisms at low frequencies in the guinea pig

Franke, R.; Dancer, A.

doi:10.1007/bf00453634

Cited by 10 publications

(13 citation statements)

References 3 publications

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“…6 and 7; see also refs. [8][9][10]. The existence of this reactive component of cochlear input impedance subsequently was confirmed by direct measurements (11,12).…”

Section: Historical Overviewmentioning

confidence: 70%

The roles of the external, middle, and inner ears in determining the bandwidth of hearing

Ruggero

Temchin

2002

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

108

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The view seems to prevail that the frequency range of hearing is determined by the properties of the outer and middle ears. We argue that this view is an oversimplification, in part because the reactive component of cochlear input impedance, which affects the low-frequency sensitivity of the cochlea, is neglected. Further, we use comparisons of audiograms and transfer functions for stapes (or columella) velocity or pressure in scala vestibuli near the stapes footplate to show that the middle ear by itself is not responsible for limiting high-frequency hearing in the few species for which such comparisons are possible. Finally, we propose that the tonotopic organization of the cochlea plays a crucial role in setting the frequency limits of cochlear sensitivity and hence in determining the bandwidth of hearing.T his article has two purposes. The first is to argue that the often-stated notion that the shape of the audiogram is largely due to the frequency-filtering properties of the external and middle ears is an oversimplification. That notion neglects the fact that a reactive component of cochlear input impedance decreases the low-frequency sensitivity of the cochlea. More importantly, comparisons of behavioral thresholds and the magnitudes of stapes (or columella) velocity (V) or pressure in scala vestibuli near the stapes footplate (P SV ) reveal that the middle ear does not limit highfrequency hearing in the few species for which such comparisons are possible. The second purpose is to offer the hypothesis that the tonotopic organization of the cochlea makes a crucial contribution to setting the frequency limits of inner-ear responses and hence the bandwidth of hearing thresholds. Historical OverviewWhen it became evident that ''high-frequency hearing is . . . a uniquely mammalian characteristic'' (1), there was speculation on the physiological and phylogenetic origins of the frequency limitations of hearing. According to one view, high-frequency hearing in mammals ''depends on the ossicular linkage in the middle ear and may have been one of the primary sources of selective pressure that resulted in the evolutionary transformation of reptilian jaw bones into mammalian auditory ossicles'' (1). A more inclusive perspective was that ''the ossicular chain of the mammalian ear is not the only factor involved in the high-frequency sensitivity of mammals'' (2), and it was suggested that the high-frequency limit of hearing across species is well correlated with an index derived from the length and width of the basilar membrane (BM; ref.3).On the basis of theoretical considerations, it was postulated long ago that cochlear input impedance is resistive at most frequencies and that reactive components affect cochlear responses only at very low (e.g., Ͻ3-10 Hz) and very high (4, 5) frequencies, thus playing a very minor role in determining the bandwidth of hearing. However, a significant role for the cochlea in setting the low-frequency limit of hearing became evident when microphonics data suggested that cochlear input im...

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“…6 and 7; see also refs. [8][9][10]. The existence of this reactive component of cochlear input impedance subsequently was confirmed by direct measurements (11,12).…”

Section: Historical Overviewmentioning

confidence: 70%

The roles of the external, middle, and inner ears in determining the bandwidth of hearing

Ruggero

Temchin

2002

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

108

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“…Later, Zwicker ͑1977͒ confirmed some aspects of Dallos' hypothesis by studying the effect of basilar membrane biasing by LF sounds on tone-burst detection threshold. Further physiological studies regarding the transfer of LF sound into the cochlea have been performed in animals ͑Weiss et al., 1971;Nedzelnitsky, 1980;Dancer and Franke, 1980;Lynch et al, 1982;Franke and Dancer, 1982;Franke et al, 1985;Ruggero et al, 1986;Magnan et al, 1999͒ andin temporal bone preparations from human cadavers ͑Kurokawa andGoode, 1995;Merchant et al, 1996;Puria et al, 1997;Aibara et al, 2001;Puria, 2003͒. With the exception of Zwicker's indications, which stem from psychoacoustical experiments, data have been obtained invasively.…”

Section: Introductionmentioning

confidence: 93%

Low-frequency characteristics of human and guinea pig cochleae

Marquardt

Hensel

Mrowinski

et al. 2007

The Journal of the Acoustical Society of America

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Previous physiological studies investigating the transfer of low-frequency sound into the cochlea have been invasive. Predictions about the human cochlea are based on anatomical similarities with animal cochleae but no direct comparison has been possible. This paper presents a noninvasive method of observing low frequency cochlear vibration using distortion product otoacoustic emissions (DPOAE) modulated by low-frequency tones. For various frequencies (15-480 Hz), the level was adjusted to maintain an equal DPOAE-modulation depth, interpreted as a constant basilar membrane displacement amplitude. The resulting modulator level curves from four human ears match equal-loudness contours (ISO226:2003) except for an irregularity consisting of a notch and a peak at 45 Hz and 60 Hz, respectively, suggesting a cochlear resonance. This resonator interacts with the middle ear stiffness. The irregularity separates two regions of the middle ear transfer function in humans: A slope of 12 dB/octave below the irregularity suggests mass-controlled impedance resulting from perilymph movement through the helicotrema; a 6-dB/octave slope above the irregularity suggests resistive cochlear impedance and the existence of a traveling wave. The results from four guinea pig ears showed a 6-dB/octave slope on either side of an irregularity around 120 Hz, and agree with published data.

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“…Mechanically, the middle ear attenuates low-frequency sounds by $6 dB/octave as frequency is lowered below 1 kHz (Dallos, 1973;Cheatham and Dallos, 2001). The helicotrema shunts pressure between scala tympani (ST) and scala vestibuli, attenuating lowfrequency stimulation by $6 dB/octave below 100 Hz both in humans (Dallos, 1970) and in guinea pigs (Franke and Dancer, 1982;Salt and Hullar, 2010). The stereocilia of the inner hair cells (IHCs) are not directly coupled to the tectorial membrane but are stimulated by fluid movements in the subtectorial space (Nowotny and Gummer, 2006;; this causes IHCs to be sensitive to basilar membrane velocity and attenuates low-frequency input by 6 dB/octave below $470 Hz (Cheatham and Dallos, 2001).…”

Section: Introductionmentioning

confidence: 98%

Large endolymphatic potentials from low-frequency and infrasonic tones in the guinea pig

Salt

Lichtenhan

Gill

et al. 2013

The Journal of the Acoustical Society of America

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Responses of the ear to low-frequency and infrasonic sounds have not been extensively studied. Understanding how the ear responds to low frequencies is increasingly important as environmental infrasounds are becoming more pervasive from sources such as wind turbines. This study shows endolymphatic potentials in the third cochlear turn from acoustic infrasound (5 Hz) are larger than from tones in the audible range (e.g., 50 and 500 Hz), in some cases with peak-to-peak amplitude greater than 20 mV. These large potentials were suppressed by higher-frequency tones and were rapidly abolished by perilymphatic injection of KCl at the cochlear apex, demonstrating their third-turn origins. Endolymphatic iso-potentials from 5 to 500 Hz were enhanced relative to perilymphatic potentials as frequency was lowered. Probe and infrasonic bias tones were used to study the origin of the enhanced potentials. Potentials were best explained as a saturating response summed with a sinusoidal voltage (Vo), that was phase delayed by an average of 60° relative to the biasing effects of the infrasound. Vo is thought to arise indirectly from hair cell activity, such as from strial potential changes caused by sustained current changes through the hair cells in each half cycle of the infrasound.

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Cochlear mechanisms at low frequencies in the guinea pig

Cited by 10 publications

References 3 publications

The roles of the external, middle, and inner ears in determining the bandwidth of hearing

The roles of the external, middle, and inner ears in determining the bandwidth of hearing

Low-frequency characteristics of human and guinea pig cochleae

Large endolymphatic potentials from low-frequency and infrasonic tones in the guinea pig

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