Computational Modeling of Spontaneous Otoacoustic Emissions by the Mammalian Cochlea

2018 ◽  
Author(s):  
Julien Meaud ◽  
Thomas Bowling ◽  
Charlsie Lemons
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Dynamic Range ◽  
Micromechanical Model ◽  
Outer Hair Cells ◽  
Cell Biophysics ◽  
Three Dimensional Model ◽  
Spontaneous Otoacoustic Emissions ◽  
Broad Dynamic Range

The mammalian cochlea is a sensory system with high sensitivity, sharp frequency selectivity and a broad dynamic range. These characteristics are due to the active nonlinear feedback by outer hair cells. Because it is an active nonlinear system, the cochlea sometimes emits spontaneous otoacoustic emissions (SOAEs) that are generated in the absence of any external stimulus due to the emergence of limit cycle oscillations. In this work, we use a computational physics-based model of the mammalian cochlea to investigate the generation of SOAEs. This model includes a three-dimensional model of the fluid mechanics in the cochlear ducts, a micromechanical model for the vibrations of the cochlear structures, and a realistic model of outer hair cell biophysics. Direct simulations of SOAEs in the time-domain demonstrate that the model is able to capture key experimental observations regarding SOAEs. Parametric studies and analysis of model simulations are used to demonstrate that SOAEs are a global phenomenon that arises due to the collective action of a distributed region of the cochlea rather than from spontaneous oscillations from individual outer hair cells.

scholarly journals Overexpression of SK2 Channels Enhances Efferent Suppression of Cochlear Responses Without Enhancing Noise Resistance

2007 ◽  
Vol 97 (4) ◽  
pp. 2930-2936 ◽  
Author(s):  
Stéphane F. Maison ◽  
Lisan L. Parker ◽  
Lucy Young ◽  
John P. Adelman ◽  
Jian Zuo ◽  
...  
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Outer Hair Cells ◽  
Sk Channels ◽  
Cochlear Function ◽  
Cochlear Hair Cells ◽  
Efferent Suppression

Cochlear hair cells express SK2, a small-conductance Ca2+-activated K+ channel thought to act in concert with Ca2+-permeable nicotinic acetylcholine receptors (nAChRs) α9 and α10 in mediating suppressive effects of the olivocochlear efferent innervation. To probe the in vivo role of SK2 channels in hearing, we examined gene expression, cochlear function, efferent suppression, and noise vulnerability in mice overexpressing SK2 channels. Cochlear thresholds, as measured by auditory brain stem responses and otoacoustic emissions, were normal in overexpressers as was overall cochlear morphology and the size, number, and distribution of efferent terminals on outer hair cells. Cochlear expression levels of SK2 channels were elevated eightfold without striking changes in other SK channels or in the α9/α10 nAChRs. Shock-evoked efferent suppression of cochlear responses was significantly enhanced in overexpresser mice as seen previously in α9 overexpresser mice; however, in contrast to α9 overexpressers, SK2 overexpressers were not protected from acoustic injury. Results suggest that efferent-mediated cochlear protection is mediated by other downstream effects of ACh-mediated Ca2+ entry different from those involving SK2-mediated hyperpolarization and the associated reduction in outer hair cell electromotility.

A study of active artificial hair cell models inspired by outer hair cell somatic motility

2016 ◽  
Vol 28 (6) ◽  
pp. 811-823 ◽  
Author(s):  
Bryan S Joyce ◽  
Pablo A Tarazaga
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Dynamic Range ◽  
Outer Hair Cells ◽  
Quality Factors ◽  
Control Laws ◽  
Sensor Performance ◽  
Nonlinear Amplification ◽  
Key Aspects

The cochlea displays an important, nonlinear amplification of sound-induced oscillations. In mammals, this amplification is largely powered by the somatic motility of the outer hair cells. The resulting cochlear amplifier has three important characteristics useful for hearing: an amplification of responses from low sound pressures, an improvement in frequency selectivity, and an ability to transduce a broad range of sound pressure levels. These useful features can be incorporated into designs for active artificial hair cells, bio-inspired sensors for use as microphones, accelerometers, or other dynamic sensors. The sensor consists of a cantilever beam with piezoelectric actuators. A feedback controller applies a voltage to the actuators to mimic the outer hair cells’ somatic motility. This article describes three control laws for an active artificial hair cell inspired by models of the outer hair cells’ somatic motility. The first control law is based on a phenomenological model of the cochlea while the second and third models incorporate physiological aspects of the biological cochlea to further improve sensor performance. Simulations show that these models qualitatively reproduce the key aspects of the mammalian cochlea, namely, amplification of oscillations from weak stimuli, higher quality factors, and a wider input dynamic range.

scholarly journals THE STUDY OF MATURATION OF THE AUDITORY ANALYZER RABBIT ACCORDING DISTORTION-PRODUCT OTOACOUSTIC EMISSIONS

2013 ◽  
Vol 68 (11) ◽  
pp. 94-97
Author(s):  
I. N. D'yakonova ◽  
Yu. S. Ishanova ◽  
I. V. Rakhmanova
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Normative Data ◽  
Outer Hair Cell ◽  
Rabbit Model ◽  
Outer Hair Cells ◽  
Distortion Product Otoacoustic Emissions ◽  
Acoustic Response ◽  
Auditory Analyzer ◽  
Distortion Product

Aim: In our chronic experiment to  register changes of acoustic response of Distortion-Product Otoacoustic Emissions (DPOAE) of intact rabbits in postnatal ontogenesis for the purpose of getting normative data which can be used for studying impact of pathological factors on auditory function and maturation of activity of outer hair cell in ontogenesis. Materials and methods: Study of otoacoustic emissions used mature chinchilla rabbits with a 19 day life of up to 3 months. Results: in the course of ripening were obtained functional activity of outer hair cells of the cochlea. Conclusion: normative data obtained allow us to study using a rabbit model, the pathological effects of agents on the maturation of the outer hair cells of the cochlea in the experiment.

The location and mechanism of electromotility in guinea pig outer hair cells

1993 ◽  
Vol 70 (2) ◽  
pp. 549-558 ◽  
Author(s):  
R. Hallworth ◽  
B. N. Evans ◽  
P. Dallos
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Length Change ◽  
Opposite Polarity ◽  
Outer Hair Cells ◽  
Response Amplitude ◽  
Change Function ◽  
Length Changes ◽  
Diameter Change

1. The microchamber method was used to examine the motile responses of isolated guinea pig outer hair cells to electrical stimulation. In the microchamber method, an isolated cell is drawn partway into a suction pipette and stimulated transcellularly. The relative position of the cell in the microchamber is referred to as the exclusion fraction. 2. The length changes of the included and excluded segments were compared for constant sinusoidal stimulus amplitude as functions of the exclusion fraction. Both included and excluded segments showed maximal responses when the cell was excluded approximately halfway. Both segments showed smaller or absent responses when the cell was almost fully excluded or almost fully included. 3. When the cell was near to, but not at, the maximum exclusion, the included segment response amplitude was zero, whereas the excluded segment response amplitude was nonzero. In contrast, when the cell was nearly fully included, the excluded segment response amplitude was zero, but the included segment response amplitude was still detectable. A simple model of outer hair cell motility based on these results suggests that the cell has finite-resistance terminations and that the motors are restricted to a region above the nucleus and below its ciliated apex (cuticular plate). 4. The function describing length change as a function of command voltage was measured for each segment as the exclusion fraction was varied. The functions were similar at midrange exclusions (i.e., when the segments were about equal length), showing nonlinearity and saturability. The functions were strikingly different when the segment lengths were different. The effects of exclusion on the voltage to length-change functions suggested that the nonlinearity and saturability are local properties of the motility mechanism. 5. The diameter changes of both segments were examined. The segment diameter changes were always antiphasic to the length changes. This finding implies that the motility mechanism has an active antiphasic diameter component. The diameter change amplitude was a monotonically increasing function of exclusion for the included segment, and a decreasing function for the excluded segment. 6. The voltage to length-change and voltage to diameter-change functions were measured for the same cell and exclusion fraction. The voltage to diameter-change function was smaller in amplitude than the voltage to length-change function. The functions were of opposite polarity to each other, but were otherwise similar in character. Thus it is likely that the same motor mechanism is responsible for both axial and diameter deformations.

DPOAE-Grams in Patients with Acute Tonal Tinnitus

2005 ◽  
Vol 132 (4) ◽  
pp. 550-553 ◽  
Author(s):  
Haralampos Gouveris ◽  
Jan Maurer ◽  
Wolf Mann
Keyword(s):  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Cell Function ◽  
Hearing Threshold ◽  
Normal Hearing ◽  
Outer Hair Cells ◽  
Controlled Study ◽  
High Frequency Region ◽  
Mean Values ◽  
Distortion Products

OBJECTIVE: To investigate cochlear outer hair cell function in patients with acute tonal tinnitus and normal or near-normal hearing threshold. STUDY DESIGN AND SETTING: Prospective controlled study in an academic tertiary health center. Distortion products of otoacoustic emissions (DPOAE)-grams of 32 ears with acute tonal tinnitus and normal hearing or minimal hearing loss were compared with those of 17 healthy nontinnitus ears. RESULTS: Tinnitus ears exhibited relatively increased amplitudes of DPOAE at high frequencies (4-6.3 kHz) when compared with the group of healthy ears and relatively decreased DPOAE amplitudes at middle frequencies (1650-2400 Hz). Statistically significant ( P < 0.01) increased mean values of DPOAE amplitudes were observed only at a frequency of f2 equal to 4.9 kHz. CONCLUSIONS AND SIGNIFICANCE: These findings suggest an altered functional state of the outer hair cells at a selected high-frequency region of the cochlea in ears with acute tonal tinnitus and normal or near-normal hearing threshold.

Early Evidence of Cochlear Damage in a Large Sample of Percussionists

2005 ◽  
Vol 20 (3) ◽  
pp. 135-139
Author(s):  
Jodee A Pride ◽  
David R Cunningham
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Cell Damage ◽  
Normal Hearing ◽  
Outer Hair Cells ◽  
Sensory Loss ◽  
Distortion Product ◽  
Hair Cell Damage

Percussionists can be exposed to intermittent sound stimuli that exceed 145 dB SPL, although damage may occur to the outer hair cells at levels of 120 dB SPL. The present study measured distortion-product otoacoustic emissions (DPOAEs) in a group of 86 normal-hearing percussionists and 39 normal-hearing nonpercussionists. Results indicate that normal-hearing percussionists have lower DPOAE amplitudes than normal-hearing nonpercussionists. DPOAE amplitudes were significantly lower at 6000 Hz in both the left and right ears for percussionists. Percussionists also more frequently had absent DPOAEs, with the greatest differences occurring at 6000 Hz (absent DPOAEs in 25% of percussionists vs 10% of nonpercussionists). When all frequencies are considered as a group, 33% of the percussionists had an absent DPOAE in either ear at some frequency, compared to only 23% of the nonpercussionists. Otoacoustic emissions are more sensitive to outer hair cell damage than pure-tone threshold measurements and can serve as an important measurement of sensory loss (i.e., outer hair cell damage) in musicians before the person perceives the hearing loss. DPOAE monitoring for musicians, along with appropriate education and intervention, might help prevent or minimize music-induced hearing loss.

Protection against Noise Trauma by Sound Conditioning

1997 ◽  
Vol 76 (4) ◽  
pp. 248-255 ◽  
Author(s):  
Barbara Canlon
Keyword(s):  
Otoacoustic Emissions ◽  
Outer Hair Cell ◽  
Human Subjects ◽  
Acoustic Stimulus ◽  
Conditioning Stimulus ◽  
Outer Hair Cells ◽  
Noise Trauma ◽  
Distortion Product ◽  
Underlying Mechanisms ◽  
X 24

Sound conditioning provides protection against a subsequent noise trauma. The sound conditioning paradigm consists of a low-level, long-term, non-damaging acoustic stimulus (1 kHz, 81 dB SPL x 24 days). Morphological and physiological alterations are not induced by the sound conditioning stimulus alone. In addition, the middle ear muscles have been shown not to be influenced by sound conditioning. It has been shown that after exposure to a traumatic stimulus, sound conditioning protects the outer hair cell morphology (fewer missing outer hair cells), as well as physiology (distortion product otoacoustic emissions) compared to an unconditioned group exposed only to the traumatic stimulus. Further studies are needed in order to establish the underlying mechanisms for the phenomenon of sound conditioning. Nevertheless, since sound-conditioning experiments have been successfully applied to human subjects our understanding of hearing impaired individuals has been enhanced.

scholarly journals Disruption of Atg7-dependent autophagy causes electromotility disturbances, outer hair cell loss, and deafness in mice

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Han Zhou ◽  
Xiaoyun Qian ◽  
Nana Xu ◽  
Shasha Zhang ◽  
Guangjie Zhu ◽  
...  
Keyword(s):  
Hair Cells ◽  
Outer Hair Cell ◽  
Cell Loss ◽  
Outer Hair Cells ◽  
Hair Cell Loss ◽  
Timely Manner ◽  
Profound Hearing Loss ◽  
Genetic Ablation ◽  
Hearing Function ◽  
Over Time

Abstract Atg7 is an indispensable factor that plays a role in canonical nonselective autophagy. Here we show that genetic ablation of Atg7 in outer hair cells (OHCs) in mice caused stereocilium damage, somatic electromotility disturbances, and presynaptic ribbon degeneration over time, which led to the gradual wholesale loss of OHCs and subsequent early-onset profound hearing loss. Impaired autophagy disrupted OHC mitochondrial function and triggered the accumulation of dysfunctional mitochondria that would otherwise be eliminated in a timely manner. Atg7-independent autophagy/mitophagy processes could not compensate for Atg7 deficiency and failed to rescue the terminally differentiated, non-proliferating OHCs. Our results show that OHCs orchestrate intricate nonselective and selective autophagic/mitophagy pathways working in concert to maintain cellular homeostasis. Overall, our results demonstrate that Atg7-dependent autophagy plays a pivotal cytoprotective role in preserving OHCs and maintaining hearing function.

scholarly journals Calcium Modulates the Frequency and Amplitude of Spontaneous Otoacoustic Emissions in the Bobtail Skink

2004 ◽  
Vol 92 (5) ◽  
pp. 2685-2693 ◽  
Author(s):  
Geoffrey A. Manley ◽  
Ulrike Sienknecht ◽  
Christine Köppl
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Calcium Concentration ◽  
Chelating Agent ◽  
Lizard Species ◽  
Spontaneous Otoacoustic Emissions ◽  
Active Processes

Active processes in the inner ear of lizards can be monitored using spontaneous otoacoustic emissions (SOAE) measured outside the eardrum. In the Australian bobtail lizard, SOAE are generated by an active motility process in the hair-cell bundle. This mechanism has been shown to be sensitive to the calcium-chelating agent 1,2-bis(o-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid and is presumed to be related to the calcium-sensitive transduction-channel motor implicated in other nonmammalian hair cell systems. In studies of frog saccular and turtle auditory papillar hair cells in vitro, the frequency and amplitude of bundle oscillations depend on the concentration of calcium in the bathing solutions. In the present study, the calcium concentration in the endolymph was changed in vivo in the Australian bobtail lizard Tiliqua rugosa, and SOAE were monitored. Glass pipettes with large tips and containing different calcium concentrations in their fluids were introduced into scala media, and their contents were allowed to passively flow into the endolymph. Low calcium concentrations resulted in a downward shift in the frequency of SOAE spectral peaks and generally an increase in their amplitudes. Calcium concentrations >2 mM resulted in increases in frequency of SOAE peaks and generally a loss in amplitude. These frequency shifts were consistent with in vitro data on the frequencies and amplitudes of spontaneous oscillation of hair cell bundles and thus also implicate calcium ions in the generation of active motility in nonmammalian hair cells. The data also suggest that in this lizard species, the ionic calcium concentration in the cochlear endolymph is ≥1 mM.

scholarly journals Low-frequency sound affects active micromechanics in the human inner ear

2014 ◽  
Vol 1 (2) ◽  
pp. 140166 ◽  
Author(s):  
Kathrin Kugler ◽  
Lutz Wiegrebe ◽  
Benedikt Grothe ◽  
Manfred Kössl ◽  
Robert Gürkov ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Low Frequency ◽  
Short Exposure ◽  
Low Frequencies ◽  
Spontaneous Otoacoustic Emissions ◽  
Human Cochlea ◽  
Human Hearing ◽  
The Impact

Noise-induced hearing loss is one of the most common auditory pathologies, resulting from overstimulation of the human cochlea, an exquisitely sensitive micromechanical device. At very low frequencies (less than 250 Hz), however, the sensitivity of human hearing, and therefore the perceived loudness is poor. The perceived loudness is mediated by the inner hair cells of the cochlea which are driven very inadequately at low frequencies. To assess the impact of low-frequency (LF) sound, we exploited a by-product of the active amplification of sound outer hair cells (OHCs) perform, so-called spontaneous otoacoustic emissions. These are faint sounds produced by the inner ear that can be used to detect changes of cochlear physiology. We show that a short exposure to perceptually unobtrusive, LF sounds significantly affects OHCs: a 90 s, 80 dB(A) LF sound induced slow, concordant and positively correlated frequency and level oscillations of spontaneous otoacoustic emissions that lasted for about 2 min after LF sound offset. LF sounds, contrary to their unobtrusive perception, strongly stimulate the human cochlea and affect amplification processes in the most sensitive and important frequency range of human hearing.

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