scholarly journals Modelling the Generation of the Cochlear Microphonic

2021 ◽  
Author(s):  
◽  
Mohammad Ayat
Keyword(s):  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Electrical Signal ◽  
Mechanical Activity ◽  
Cochlear Amplifier ◽  
Cochlear Microphonic ◽  
Cochlear Function ◽  
Phase Cancellation ◽  
Wide Range ◽  
Human Ear

<p>The human ear is a remarkable sensory organ. A normal healthy human ear is able to process sounds covering a wide range of frequencies and intensities, while distinguishing between different components of complex sounds such as a musical chord. In the last four decades, knowledge about the cochlea and the mechanisms involved in its operation has greatly increased, but many details about these mechanisms remain unresolved and disputed. The cochlea has a vulnerable structure. Consequently, measuring and monitoring its mechanical and electrical activities even with contemporary devices is very difficult. Modelling can be used to fill gaps between those measurements that are feasible and actual cochlear function. Modelling techniques can also help to simplify complex cochlear operation to a tractable and comprehensible level while still reproducing certain behaviours of interest. Modelling therefore can play an essential role in developing a better understanding of the cochlea. The Cochlear Microphonic (CM) is an electrical signal generated inside the cochlea in response to sound. This electrical signal reflects mechanical activity in the cochlea and the excitation processes involved in its generation. However, the difficulty of obtaining this signal and the simplicity of other methods such as otoacoustic emissions have discouraged the use of the cochlear microphonic as a tool for studying cochlear functions. In this thesis, amodel of the cochlea is presented which integrates bothmechanical and electrical aspects, enabling the interaction between them to be investigated. The resulting model is then used to observe the effect of the cochlear amplifier on the CM. The results indicate that while the cochlear amplifier significantly amplifies the basilar membrane displacement, the effect on the CM is less significant. Both of these indications agree with previous physiological findings. A novel modelling approach is used to investigate the tuning discrepancy between basilar membrane and CMtuning curves. The results suggest that this discrepancy is primarily due to transversal phase cancellation in the outer hair cell rather than longitudinal phase cancellation along the basilar membrane. In addition, the results of the model suggest that spontaneous cochlear microphonic should exist in the cochlea. The existence of this spontaneous electrical signal has not yet been reported.</p>

scholarly journals Modelling the Generation of the Cochlear Microphonic

2021 ◽  
Author(s):  
◽  
Mohammad Ayat
Keyword(s):  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Electrical Signal ◽  
Mechanical Activity ◽  
Cochlear Amplifier ◽  
Cochlear Microphonic ◽  
Cochlear Function ◽  
Phase Cancellation ◽  
Wide Range ◽  
Human Ear

<p>The human ear is a remarkable sensory organ. A normal healthy human ear is able to process sounds covering a wide range of frequencies and intensities, while distinguishing between different components of complex sounds such as a musical chord. In the last four decades, knowledge about the cochlea and the mechanisms involved in its operation has greatly increased, but many details about these mechanisms remain unresolved and disputed. The cochlea has a vulnerable structure. Consequently, measuring and monitoring its mechanical and electrical activities even with contemporary devices is very difficult. Modelling can be used to fill gaps between those measurements that are feasible and actual cochlear function. Modelling techniques can also help to simplify complex cochlear operation to a tractable and comprehensible level while still reproducing certain behaviours of interest. Modelling therefore can play an essential role in developing a better understanding of the cochlea. The Cochlear Microphonic (CM) is an electrical signal generated inside the cochlea in response to sound. This electrical signal reflects mechanical activity in the cochlea and the excitation processes involved in its generation. However, the difficulty of obtaining this signal and the simplicity of other methods such as otoacoustic emissions have discouraged the use of the cochlear microphonic as a tool for studying cochlear functions. In this thesis, amodel of the cochlea is presented which integrates bothmechanical and electrical aspects, enabling the interaction between them to be investigated. The resulting model is then used to observe the effect of the cochlear amplifier on the CM. The results indicate that while the cochlear amplifier significantly amplifies the basilar membrane displacement, the effect on the CM is less significant. Both of these indications agree with previous physiological findings. A novel modelling approach is used to investigate the tuning discrepancy between basilar membrane and CMtuning curves. The results suggest that this discrepancy is primarily due to transversal phase cancellation in the outer hair cell rather than longitudinal phase cancellation along the basilar membrane. In addition, the results of the model suggest that spontaneous cochlear microphonic should exist in the cochlea. The existence of this spontaneous electrical signal has not yet been reported.</p>

scholarly journals Otoacoustic Emissions from Residual Oscillations of the Cochlear Basilar Membrane in a Human Ear Model

2003 ◽  
Vol 4 (4) ◽  
pp. 478-494 ◽  
Author(s):  
Renato Nobili ◽  
Aleš Vetešnik ◽  
Lorenzo Turicchia ◽  
Fabio Mammano
Keyword(s):  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Human Ear

Loud Sound-Induced Changes in Cochlear Mechanics

2002 ◽  
Vol 88 (5) ◽  
pp. 2341-2348 ◽  
Author(s):  
Anders Fridberger ◽  
Jiefu Zheng ◽  
Anand Parthasarathi ◽  
Tianying Ren ◽  
Alfred Nuttall
Keyword(s):  
Inner Ear ◽  
Time Course ◽  
Basilar Membrane ◽  
Organ Of Corti ◽  
Compound Action Potential ◽  
Cochlear Microphonic ◽  
Cochlear Function ◽  
Loud Sound ◽  
Induced Changes ◽  
Membrane Vibrations

To investigate the inner ear response to intense sound and the mechanisms behind temporary threshold shifts, anesthetized guinea pigs were exposed to tones at 100–112 dB SPL. Basilar membrane vibration was measured using laser velocimetry, and the cochlear microphonic potential, compound action potential of the auditory nerve, and local electric AC potentials in the organ of Corti were used as additional indicators of cochlear function. After exposure to a 12-kHz intense tone, basilar membrane vibrations in response to probe tones at the characteristic frequency of the recording location (17 kHz) were transiently reduced. This reduction recovered over the course of 50 ms in most cases. Organ of Corti AC potentials were also reduced and recovered with a time course similar to the basilar membrane. When using a probe tone at either 1 or 4 kHz, organ of Corti AC potentials were unaffected by loud sound, indicating that transducer channels remained intact. In most experiments, both the basilar membrane and the cochlear microphonic response to the 12-kHz overstimulation was constant throughout the duration of the intense stimulus, despite a large loss of cochlear sensitivity. It is concluded that the reduction of basilar membrane velocity that followed loud sound was caused by changes in cochlear amplification and that the cochlear response to intense stimulation is determined by the passive mechanical properties of the inner ear structures.

scholarly journals Two-Tone Distortion on the Basilar Membrane of the Chinchilla Cochlea

1997 ◽  
Vol 77 (5) ◽  
pp. 2385-2399 ◽  
Author(s):  
Luis Robles ◽  
Mario A. Ruggero ◽  
Nola C. Rich
Keyword(s):  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Stimulus Level ◽  
Frequency Spectra ◽  
Nonmonotonic Dependence ◽  
Distortion Products ◽  
Odd Order ◽  
Wide Range ◽  
Primary Frequency ◽  
Frequency Ratios

Robles, Luis, Mario A. Ruggero, and Nola C. Rich. Two-tone distortion on the basilar membrane of the chinchilla cochlea. J. Neurophysiol. 77: 2385–2399, 1997. Basilar membrane responses to pairs of tones were measured, with the use of a laser velocimeter, in the basal turn of the cochlea in anesthetized chinchillas. Frequency spectra of basilar membrane responses to primary tones with frequencies (f1, f2) close to the characteristic frequency (CF) contain prominent odd-order two-tone distortion products (DPs) at frequencies both higher and lower than CF (such as 2f1 − f2, 3f1 − 2f2, 2f2 − f1 and 3f2 − 2f1). For equal-level primaries with frequencies such that 2f1 − f2 equals CF, the magnitude of the2f1 − f2 DP grows with primary level at linear or faster rates at low stimulus levels, but it saturates or decreases slightly at higher levels. For a fixed level of one of the primary tones, the magnitude of the 2f1 − f2 DP is a nonmonotonic function of the level of the other primary tone. For low intensities of the variable tone, the2f1 − f2 DP grows at a rate of ∼2 dB/dB with f1 level and 1 dB/dB with f2 level. DP magnitudes decrease rapidly with increasing primary frequency ratio (f2/f1) at low stimulus levels. For more intense stimuli, DP magnitudes remain constant or decrease slowly over a wide range of frequency ratios until a critical value is reached, at which DP magnitudes fall with slopes as steep as −300 dB/octave. As stimulus level grows, DP phases increasingly lag for large f2/f1 ratios, but exhibit leads for small f2/f1 ratios. Cochlear exposure to an intense tone that produces large sensitivity losses for the primary frequencies (but only small losses for tones with frequency equal to 2f1 − f2) causes a substantial decrease in magnitude of the 2f1 − f2 DP. This result demonstrates that the 2f1 − f2 DP originates at the basilar membrane region with CFs corresponding to the primary frequencies and propagates to the location with CF equal to the DP frequency. 2f1 − f2 DPs on the basilar membrane resemble those measured in human psychophysics in most respects. However, the magnitude of basilar membrane DPs does not show the nonmonotonic dependence on f2/f1 ratio evident in DP otoacoustic emissions.

Amplitude Distributions of Cochlear Microphonic Response to an Acoustic Sinusoid in Noise

1968 ◽  
Vol 11 (1) ◽  
pp. 63-76
Author(s):  
Donald C. Teas ◽  
Gretchen B. Henry
Keyword(s):  
Small Amplitude ◽  
Basilar Membrane ◽  
Spectral Composition ◽  
Pass Band ◽  
Cochlear Microphonic ◽  
Filter Output ◽  
Electronic Filter ◽  
Low Pass ◽  
Band Pass ◽  
Instantaneous Voltage

The distributions of instantaneous voltage amplitudes in the cochlear microphonic response recorded from a small segment along the basilar membrane are described by computing amplitude histograms. Comparisons are made between the distributions for noise and for those after the addition to the noise of successively stronger sinusoids. The amplitudes of the cochlear microphonic response to 5000 Hz low-pass noise are normally distributed in both Turn I and Turn III of the guinea pig’s cochlea. The spectral composition of the microphonic from Turn I and from Turn III resembles the output of band-pass filters set at about 4000 Hz, and about 500 Hz, respectively. The normal distribution of cochlear microphonic amplitudes for noise is systematically altered by increasing the strength of the added sinusoid. A decrease of three percent in the number of small amplitude events (±1 standard deviation) in the cochlear microphonic from Turn III is seen when the rms voltage of a 500 Hz sinusoid is at −18 dB re the rms voltage of the noise (at the earphone). When the rms of the sinusoid and noise are equal, the decrease in small voltages is about 25%, but there is also an increase in the number of large voltage amplitudes. Histograms were also computed for the output of an electronic filter with a pass-band similar to Turn III of the cochlea. Strong 500 Hz sinusoids showed a greater proportion of large amplitudes in the filter output than in CM III . The data are interpreted in terms of an anatomical substrate.

scholarly journals A Review on Biosensors and Recent Development of Nanostructured Materials-Enabled Biosensors

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1109
Author(s):  
Varnakavi. Naresh ◽  
Nohyun Lee
Keyword(s):  
High Surface ◽  
Three Dimensional ◽  
Biological Response ◽  
Volume Ratio ◽  
Recent Decade ◽  
Disease Diagnosis ◽  
Electrical Signal ◽  
Detection Sensitivity ◽  
Wide Range ◽  
Color Tunability

A biosensor is an integrated receptor-transducer device, which can convert a biological response into an electrical signal. The design and development of biosensors have taken a center stage for researchers or scientists in the recent decade owing to the wide range of biosensor applications, such as health care and disease diagnosis, environmental monitoring, water and food quality monitoring, and drug delivery. The main challenges involved in the biosensor progress are (i) the efficient capturing of biorecognition signals and the transformation of these signals into electrochemical, electrical, optical, gravimetric, or acoustic signals (transduction process), (ii) enhancing transducer performance i.e., increasing sensitivity, shorter response time, reproducibility, and low detection limits even to detect individual molecules, and (iii) miniaturization of the biosensing devices using micro-and nano-fabrication technologies. Those challenges can be met through the integration of sensing technology with nanomaterials, which range from zero- to three-dimensional, possessing a high surface-to-volume ratio, good conductivities, shock-bearing abilities, and color tunability. Nanomaterials (NMs) employed in the fabrication and nanobiosensors include nanoparticles (NPs) (high stability and high carrier capacity), nanowires (NWs) and nanorods (NRs) (capable of high detection sensitivity), carbon nanotubes (CNTs) (large surface area, high electrical and thermal conductivity), and quantum dots (QDs) (color tunability). Furthermore, these nanomaterials can themselves act as transduction elements. This review summarizes the evolution of biosensors, the types of biosensors based on their receptors, transducers, and modern approaches employed in biosensors using nanomaterials such as NPs (e.g., noble metal NPs and metal oxide NPs), NWs, NRs, CNTs, QDs, and dendrimers and their recent advancement in biosensing technology with the expansion of nanotechnology.

Evaluating cochlear function and the effects of noise exposure in the B6.CAST+Ahl mouse with distortion product otoacoustic emissions

2004 ◽  
Vol 194 (1-2) ◽  
pp. 87-96 ◽  
Author(s):  
Ana E Vázquez ◽  
Ana M Jimenez ◽  
Glen K Martin ◽  
Anne E Luebke ◽  
Brenda L Lonsbury-Martin
Keyword(s):  
Otoacoustic Emissions ◽  
Noise Exposure ◽  
Distortion Product Otoacoustic Emissions ◽  
Cochlear Function ◽  
Distortion Product

Pitch related to spectral edges of broadband signals

1992 ◽  
Vol 336 (1278) ◽  
pp. 375-382 ◽  
Keyword(s):  
Fundamental Frequency ◽  
Basilar Membrane ◽  
Comparison Tone ◽  
Harmonic Signals ◽  
Wide Range ◽  
Spectral Components ◽  
Neuronal Processes ◽  
Low Pass ◽  
Harmonic Components ◽  
Hearing System

A complex tone often evokes a pitch sensation associated with its extreme spectral components, besides the holistic pitch associated with its fundamental frequency. We studied the edge pitch created at the upper spectral edge of complexes with a low-pass spectrum by asking subjects to adjust the frequency of a sinusoidal comparison tone to the perceived pitch. Measurements were performed for different values of the fundamental frequency and of the upper frequency of the complex as well as for three different phase relations of the harmonic components. For a wide range of these parameters the subjects could adjust the comparison tone with a high accuracy, measured as the standard deviation of repeated adjustments, to a frequency close to the nominal edge frequency. The detailed dependence of the matching accuracy on temporal parameters of the harmonic complexes suggests that the perception of the edge pitch in harmonic signals is related to the temporal resolution of the hearing system. This resolution depends primarily on the time constants of basilar-membrane filters and on additional limitations due to neuronal processes.

scholarly journals "Creep currents" in single frog atrial cells may be generated by electrogenic Na/Ca exchange.

1986 ◽  
Vol 87 (6) ◽  
pp. 857-884 ◽  
Author(s):  
J R Hume ◽  
A Uehara
Keyword(s):  
Voltage Clamp ◽  
Time Course ◽  
Single Cells ◽  
Mechanical Activity ◽  
Common Mechanism ◽  
Mechanical Relaxation ◽  
Equilibrium Conditions ◽  
Atrial Cells ◽  
Current Voltage ◽  
Wide Range

The objective of these experiments was to test the hypothesis that the "creep currents" induced by Na loading of single frog atrial cells (Hume, J. R., and A. Uehara. 1986. Journal of General Physiology. 87:833) may be generated by an electrogenic Na/Ca exchanger. Creep currents induced by Na loading were examined over a wide range of membrane potentials. During depolarizing voltage-clamp pulses, outward creep currents were observed, followed by inward creep currents upon the return to the holding potential. During hyperpolarizing voltage-clamp pulses, creep currents of the opposite polarity were observed: inward creep currents were observed during the pulses, followed by outward creep currents upon the return to the holding potential. The current-voltage relations for inward and outward creep currents in response to depolarizing or hyperpolarizing voltage displacements away from the holding potential all intersect the voltage axis at a common potential, which indicates that inward and outward creep currents may have a common reversal potential under equilibrium conditions and may therefore be generated by a common mechanism. Measurements of inward creep currents confirm that voltage displacements away from the holding potential rapidly alter equilibrium conditions. Current-voltage relationships of inward creep currents after depolarizing voltage-clamp pulses are extremely labile and depend critically upon the amplitude and duration of outward creep currents elicited during preceding voltage-clamp pulses. An optical monitor of mechanical activity in single cells revealed (a) a similar voltage dependence for the outward creep currents induced by Na loading and tonic contraction, and (b) a close correlation between the time course of the decay of the inward creep current and the time course of mechanical relaxation. A mathematical model of electrogenic Na/Ca exchange (Mullins, L.J. 1979. Federation Proceedings. 35:2583; Noble, D. 1986. Cardiac Muscle. 171-200) can adequately account for many of the properties of creep currents. It is concluded that creep currents in single frog atrial cells may be attributed to the operation of an electrogenic Na/Ca exchange mechanism.

Early Changes in Auditory Function As a Result of Platinum Chemotherapy: Use of Extended High-Frequency Audiometry and Evoked Distortion Product Otoacoustic Emissions

2007 ◽  
Vol 25 (10) ◽  
pp. 1190-1195 ◽  
Author(s):  
Kristin R. Knight ◽  
Dale F. Kraemer ◽  
Christiane Winter ◽  
Edward A. Neuwelt
Keyword(s):  
High Frequency ◽  
Otoacoustic Emissions ◽  
Distortion Product Otoacoustic Emissions ◽  
Auditory Function ◽  
Cochlear Function ◽  
Serial Measurement ◽  
Distortion Product ◽  
High Frequency Audiometry ◽  
Platinum Based Chemotherapy ◽  
Platinum Chemotherapy

Purpose The objective is to describe progressive changes in hearing and cochlear function in children and adolescents treated with platinum-based chemotherapy and to begin preliminary evaluation of the feasibility of extended high-frequency audiometry and distortion product otoacoustic emissions for ototoxicity monitoring in children. Patients and Methods Baseline and serial measurement of conventional pure-tone audiometry (0.5 to 8 kHz) and evoked distortion product otoacoustic emissions (DPOAEs) were conducted for 32 patients age 8 months to 20 years who were treated with cisplatin and/or carboplatin chemotherapy. Seventeen children also had baseline and serial measurement of extended high-frequency (EHF) audiometry (9 to 16 kHz). Audiologic data were analyzed to determine the incidence of ototoxicity using the American Speech-Language-Hearing Association criteria, and the relationships between the different measures of ototoxicity. Results Of the 32 children, 20 (62.5%) acquired bilateral ototoxicity in the conventional frequency range during chemotherapy treatment, and 26 (81.3%) had bilateral decreases in DPOAE amplitudes and dynamic range. Of the 17 children with EHF audiometry results, 16 (94.1%) had bilateral ototoxicity in the EHF range. Pilot data suggest that EHF thresholds and DPOAEs show ototoxic changes before hearing loss is detected by conventional audiometry. Conclusion EHF audiometry and DPOAEs have the potential to reveal earlier changes in auditory function than conventional frequency audiometry during platinum chemotherapy in children.

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