Does tinnitus originate from hyperactive nerve fibers in the cochlea?

1984 ◽  
Vol 98 (S9) ◽  
pp. 38-44 ◽  
Author(s):  
Richard S. Tyler
Keyword(s):  
Basilar Membrane ◽  
Tuning Curve ◽  
Nerve Fibers ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Physiological Data ◽  
Pitch Matching ◽  
Category Scaling ◽  
Tinnitus Masking ◽  
Peripheral Origin

AbstractThis paper discusses the possibility of a localized peripheral origin of tinnitus. A working hypothesis is that tinnitus represents either aperiodic or periodic hyperactivity in the spontaneous activity of nerve fibers originating from a restricted place on the basilar membrane. The limited physiological data available support both hyperactive and hypoactive nerve fiber. Psychophysical data are not easy to interpret. Subjective descriptions and category scaling are too dependent on individual experience. Pitch matching can be reliable, but cannot distinguish between peripheral or central tinnitus. In one experiment we compared the masking of tinnitus to the masking of a pure tone, where the signal frequency and level were obtained from the tinnitus pitch and loudness matching. The results indicate that the broad tinnitus masking patterns are not typically due to the poor frequency resolution observed in sensorineural hearing loss. However, in a few subjects there was some correspondence between the shape of the tuning curve and the tinnitus masking pattern. In another study, we masked tinnitus with narrowband noises of different bandwidths. In some patients, there was a ‘critical bandwidth’ effect; wider masker bandwidths required greater overall sound pressures to mask the tinnitus. We conclude that the results from these studies taken together indicate that there are different types of tinnitus, some of which may have a localized peripheral origin.

Masking of Tinnitus Compared to Masking of Pure Tones

1984 ◽  
Vol 27 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Richard S. Tyler ◽  
David Conrad-Armes
Keyword(s):  
Tuning Curve ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Frequency Range ◽  
Apparent Relationship ◽  
Pure Tones ◽  
Frequency Threshold ◽  
High Level ◽  
Tinnitus Masking

In 10 subjects with sensorineural tinnitus (associated with a sensorineural hearing loss and no apparent source for a tinnitus originating elsewhere), the minimum level required to mask the tinnitus was determined for tonal maskers at several masker frequencies. This tinnitus masking pattern was compared to a psychoacoustical tuning curve (PTC) in which the signal frequency and level were determined from tinnitus pitch and loudness matching. Different patterns emerged. One subject showed a near-normal PTC but required high-level maskers across the frequency range to mask the tinnitus. Another subject showed some frequency resolution in the PTC but required low-level maskers across the frequency range to mask the tinnitus. For the remaining eight subjects, the masker levels required to mask the tone were generally higher than those levels required to mask the tinnitus. In addition, it was noted that the tinnitus pitch-match frequency was sometimes associated with an increase or a decrease in threshold sensitivity, or it was found at the low-frequency edge of a steep high-frequency threshold loss. In other subjects there was no apparent relationship between the tinnitus pitch and the audiogram shape.

Electron Microscopic Findings in Presbycusic Degeneration of the Basal Turn of the Human Cochlea

1979 ◽  
Vol 87 (6) ◽  
pp. 818-836 ◽  
Author(s):  
Joseph B. Nadol
Keyword(s):  
Light Microscopy ◽  
Hair Cells ◽  
Basilar Membrane ◽  
Ganglion Cells ◽  
Nerve Fibers ◽  
Degenerative Changes ◽  
Supporting Cells ◽  
Neural Degeneration ◽  
Basal Turn ◽  
Temporal Bones

Three human temporal bones with presbycusis affecting the basal turn of the cochlea were studied by light and electron microscopy. Conditions in two ears examined by light microscopy were typical of primary neural degeneration, with a descending audiometric pattern, loss of cochlear neurons in the basal turn, and preservation of the organ of Corti. Ultrastructural analysis revealed normal hair cells and marked degenerative changes of the remaining neural fibers, especially in the basal turn. These changes included a decrease in the number of synapses at the base of hair cells, accumulation of cellular debris in the spiral bundles, abnormalities of the dendritic fibers and their sheaths in the osseous spiral lamina, and degenerative changes in the spiral ganglion cells and axons. These changes were interpreted as an intermediate stage of degeneration prior to total loss of nerve fibers and ganglion cells as visualized by light microscopy. In the third ear the changes observed were typical of primary degeneration of hair and supporting cells in the basal turn with secondary neural degeneration. Additional observations at an ultrastructural level included maintenance of the tight junctions of the scala media despite loss of both hair and supporting cells, suggesting a capacity for cellular “healing” in the inner ear. Degenerative changes were found in the remaining neural fibers in the osseous spiral lamina. In addition, there was marked thickening of the basilar membrane in the basal turn, which consisted of an increased number of fibrils and an accumulation of amorphous osmiophilic material in the basilar membrane. This finding supports the concept that mechanical alterations may occur in presbycusis of the basal turn.

Tinnitus: some thoughts about its origin

1984 ◽  
Vol 98 (S9) ◽  
pp. 31-37 ◽  
Author(s):  
J. J. Eggermont
Keyword(s):  
Hair Cells ◽  
High Frequency ◽  
Basilar Membrane ◽  
Stimulus Frequency ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Ear Ossicles ◽  
Stimulus Transduction ◽  
Low Levels ◽  
Inner Ear Fluids

An auditory sensation follows generally as the result of the sequence stimulus, transduction, coding, transformation and sensation. This is then optionally followed by perception and a reaction. The stimulus is usually airborne sound causing movements of the tympanic membrane, the middle ear ossicles, the inner ear fluids and the basilar membrane. The movements of the basilar membrane are dependent on stimulus frequency: high frequency tones excite only the basal part of the cochlea, regardless of the stimulus intensity; low frequency tones at low levels only excite the so-called place specific region at the apical end but at high levels (above 60–70 dB SPL) cause appreciable movement of the entire basilar membrane. Basilar membrane tuning is as sharp as that of inner hair cells or auditory nerve fibers (Sellick et al., 1982) at least in the basal turn of animals that have a cochlea in physiologically impeccable condition.

Design of DDS Based on FPGA Technology

2015 ◽  
Vol 713-715 ◽  
pp. 1031-1033
Author(s):  
Wei Jiang ◽  
Fang Yuan ◽  
Liu Qing Yang
Keyword(s):  
High Frequency ◽  
Simple Structure ◽  
Frequency Synthesizer ◽  
Sine Wave ◽  
Lookup Table ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Small Delay ◽  
Working Principle ◽  
Output Only

This paper introduces the working principle and structure of direct digital frequency synthesizer. This paper select the technology of lookup table to design DDS because it has many advantages such as less consumption hardware resources, simple structure, output only small delay and so on. As a result, signal generator can produce many waveforms with good stability and high frequency resolution. Finally, test showed that the output wave of triangular signal frequency is greater than 1MHz and the highest sine wave frequency is 30MHz, the value of peak to peak is continuously adjustable in 50mV ~ 4V range. The result of study will provide theoretical guidance for the design of DDS.

Pitch strength and annoyance of acoustic analogs of flutter echo - a pilot study

2021 ◽  
Vol 263 (4) ◽  
pp. 2145-2156
Author(s):  
Anne Balant ◽  
Heather Lai ◽  
Vayda M. Wilson
Keyword(s):  
College Students ◽  
User Interface ◽  
Pilot Study ◽  
Graphical User Interface ◽  
Scaling Method ◽  
Short Pulses ◽  
Pulse Trains ◽  
Pitch Matching ◽  
Category Scaling

The impetus for this pilot study was the observation of flutter echoes on the aisle of a church with a barrel-vaulted ceiling. When source and receiver height were comparable, the flutter echoes consisted of a 39-msec repeating pattern of three short pulses that persisted for reverberation times of up to 5 sec. The disruptive quality of these echoes perceptually was striking. It was hypothesized that the perception of a sequence of rapidly alternating periodicity pitches might be the source of this disruptive quality. A pilot study was conducted to assess the perceived pitch, pitch strength, and annoyance of isochronous and anisochronous synthetic pulse trains involving up to three different inter-pulse intervals per pattern. Intervals of the anisochronous pulse trains were controlled to create harmonic and inharmonic relationships among the intervals, which ranged from 5-20 msec. Twelve adult college students participated in the study remotely via videoconferencing due to social distancing requirements. A modified category scaling method was used. Participants positioned a slider on a graphical user interface to reflect their ratings of pitch strength and annoyance and used a slider to adjust the frequency of a reference tone for pitch matching. Results and implications for further research will be presented.

scholarly journals A point process framework for modeling electrical stimulation of the auditory nerve

2012 ◽  
Vol 108 (5) ◽  
pp. 1430-1452 ◽  
Author(s):  
Joshua H. Goldwyn ◽  
Jay T. Rubinstein ◽  
Eric Shea-Brown
Keyword(s):  
Electrical Stimulation ◽  
Point Process ◽  
Pulse Rate ◽  
Auditory Nerve ◽  
Electric Stimulation ◽  
Nerve Fibers ◽  
Ideal Observer ◽  
Physiological Data ◽  
Auditory Nerve Fibers ◽  
Insight Into

Model-based studies of responses of auditory nerve fibers to electrical stimulation can provide insight into the functioning of cochlear implants. Ideally, these studies can identify limitations in sound processing strategies and lead to improved methods for providing sound information to cochlear implant users. To accomplish this, models must accurately describe spiking activity while avoiding excessive complexity that would preclude large-scale simulations of populations of auditory nerve fibers and obscure insight into the mechanisms that influence neural encoding of sound information. In this spirit, we develop a point process model of individual auditory nerve fibers that provides a compact and accurate description of neural responses to electric stimulation. Inspired by the framework of generalized linear models, the proposed model consists of a cascade of linear and nonlinear stages. We show how each of these stages can be associated with biophysical mechanisms and related to models of neuronal dynamics. Moreover, we derive a semianalytical procedure that uniquely determines each parameter in the model on the basis of fundamental statistics from recordings of single fiber responses to electric stimulation, including threshold, relative spread, jitter, and chronaxie. The model also accounts for refractory and summation effects that influence the responses of auditory nerve fibers to high pulse rate stimulation. Throughout, we compare model predictions to published physiological data of response to high and low pulse rate stimulation. We find that the model, although constructed to fit data from single and paired pulse experiments, can accurately predict responses to unmodulated and modulated pulse train stimuli. We close by performing an ideal observer analysis of simulated spike trains in response to sinusoidally amplitude modulated stimuli and find that carrier pulse rate does not affect modulation detection thresholds.

The Design of Signal Generator of Electrical Fast Transients Burst

2013 ◽  
Vol 336-338 ◽  
pp. 27-32 ◽  
Author(s):  
Wu Zhu ◽  
Jia Min Zhang ◽  
Yuan Zhang ◽  
Juan Juan Yu ◽  
Shi Bing Wu
Keyword(s):  
Output Signal ◽  
Pulse Width ◽  
Linear Array ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Direct Digital Frequency Synthesis ◽  
Waveform Data ◽  
Amplitude Attenuation ◽  
Fast Transients ◽  
Frequency Changes

With the improvement of output frequency of electric fast transients (EFT) burst generator, amplitude attenuation of pulse train appeared in the high frequency. Therefore, the method of pulse width programmed digitally ,and realized by Field Programmable Gate Array (FPGA) device was put forward to overcome burst amplitude attenuation. The technology of direct digital frequency synthesis was used to adjust the output signal frequency changes. The linear array memory with one bit was adopted to store square-wave waveform, the output signal duty cycle is digital adjustable, which is achieved by changing the waveform data in the linear array memory. Brust generator is designed by using VHDL languages in the QUARTUS II 6.0 simulation platform. The simulation and experiment results show that when the frequency of the output signal reaches 1 MHz, frequency resolution arrives at 6Hz, error of pulse width is less than 10 ns.

Measurement of Vibration of the Basilar Membrane in the Squirrel Monkey

1974 ◽  
Vol 83 (5) ◽  
pp. 619-625 ◽  
Author(s):  
William S. Rhode
Keyword(s):  
Resonant Frequency ◽  
Squirrel Monkey ◽  
Basilar Membrane ◽  
Low Frequency ◽  
Wave Theory ◽  
Resonance Curve ◽  
Nerve Fibers ◽  
Neural Data ◽  
Oscillatory Response ◽  
Resonance Curves

The Mössbauer technique, which can be used to measure very small velocities, on the order of 0.2 mm/sec, has been used to measure the response of the basilar membrane to tones and clicks in squirrel monkeys. The results verify that there is a mechanical frequency analysis performed in the cochlea and that the traveling wave theory holds true. The resonance curves indicate that the tuning of the basilar membrane is greater than was thought. The basilar membrane in the 7–8 kHz region of the cochlea vibrates nonlinearly at frequencies near the “resonant frequency.” The click response shows that the “tail” of the decaying oscillatory response does not decrease in proportion to click amplitude while the early displacements of the basilar membrane have a nearly linear relationship with click amplitude. These results are in good agreement with the results of the measurements using tones as stimuli. Experiments examining postmortem behavior of the basilar membrane indicate a rapid decrease in the sensitivity of vibration along with a decrease of up to one octave in the “resonant” frequency within a six hour period after the animal's death. The shift in resonant frequency is accompanied by a corresponding shift in the phase characteristic. The low frequency slope of the resonance curve becomes 6 dB/octave exactly as Békésy found while the high frequency slope decreases slightly. Comparison of the mechanical resonance curves with the neural data for single auditory nerve fibers in the squirrel monkey indicates that the exquisite tuning exhibited in the nerve cannot be explained solely on the basis of the mechanical behavior of the basilar membrane.

Otoacoustic Emissions as a Promising Diagnostic Tool for the Early Detection of Mild Hearing Impairment - Technical Advances in Acquisition, Analysis and Modeling

2016 ◽  
Vol 879 ◽  
pp. 2355-2360
Author(s):  
Arturo Moleti ◽  
Renata Sisto ◽  
Filippo Sanjust ◽  
Teresa Botti ◽  
Sandro Gentili
Keyword(s):  
Diagnostic Tool ◽  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Hearing Threshold ◽  
High Sensitivity ◽  
Outer Hair Cells ◽  
Frequency Resolution ◽  
Phase Gradient ◽  
Time Frequency ◽  
Generation Mechanisms

Otoacoustic emissions are a by-product of the active nonlinear amplification mechanism located in the cochlear outer hair cells, which provides high sensitivity and frequency resolution to human hearing. Being intrinsically sensitive to hearing loss at a cochlear level, they represent a promising non-invasive, fast, and objective diagnostic tool. On the other hand, the complexity of their linear and nonlinear generation mechanisms and other confounding physical phenomena (e.g., interference between different otoacoustic components, acoustical resonances in the ear canal, transmission of the middle ear) introduce a large inter-subject variability in their measured levels, which makes it difficult using them as a direct measure of the hearing threshold using commercially available devices. Nonlinear cochlear modeling has been successfully used to understand the complexity of the otoacoustic generation mechanisms, and to design new acquisition and analysis techniques that help disentangling the different components of the otoacoustic response, therefore improving the correlation between measured otoacoustic levels and audiometric thresholds. In particular, nonlinear cochlear modeling was able to effectively describe the complex (amplitude and phase) response of the basilar membrane, and the generation of otoacoustic emissions by two mechanisms, nonlinear distortion and linear reflection by cochlear roughness. Different phase-frequency relations are predicted for the otoacoustic components generated by the two mechanisms, so they can be effectively separated according to their different phase-gradient delay, using an innovative time-frequency domain filtering technique based on the wavelet transform. A brief introduction to these topics and some new theoretical and experimental results are presented and discussed in this study.

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