A non-invasive Cochlear Microphonic measurement system

Masood, Asim; Teal, Paul D.; Hollitt, Christopher

doi:10.1016/j.medengphy.2012.06.017

Cited by 7 publications

(11 citation statements)

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“…The CM can be observed by placing an electrode on the surface of the cochlea [194] or with glass micropipette electrodes inserted in the scala media [220]. The CM can also be obtained as a far field signal which can be recorded noninvasively by placing electrodes inside the ear canal or invasively by placing electrodes on or close to the round window membrane [184, 221]. This potential can be used to assess the MET current of outer hair cells ([222–224]) checking the biological effects of infrasound on the human auditory system [225, 226], diagnosing Ménière's disease [227], and diagnosis of auditory neuropathy spectrum disorder [228].…”

Section: Electrical Couplingmentioning

confidence: 99%

Modelling Cochlear Mechanics

Elliott

Ayat

et al. 2014

BioMed Research International

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The cochlea plays a crucial role in mammal hearing. The basic function of the cochlea is to map sounds of different frequencies onto corresponding characteristic positions on the basilar membrane (BM). Sounds enter the fluid-filled cochlea and cause deflection of the BM due to pressure differences between the cochlear fluid chambers. These deflections travel along the cochlea, increasing in amplitude, until a frequency-dependent characteristic position and then decay away rapidly. The hair cells can detect these deflections and encode them as neural signals. Modelling the mechanics of the cochlea is of help in interpreting experimental observations and also can provide predictions of the results of experiments that cannot currently be performed due to technical limitations. This paper focuses on reviewing the numerical modelling of the mechanical and electrical processes in the cochlea, which include fluid coupling, micromechanics, the cochlear amplifier, nonlinearity, and electrical coupling.

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Section: Electrical Couplingmentioning

confidence: 99%

Modelling Cochlear Mechanics

Elliott

Ayat

et al. 2014

BioMed Research International

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“…Our simulations based on human calibrated parameter values indicate that the amplitude of the SCOMIC can be in the range of one microvolt, similar to other bio-signals. We have attempted to detect CM with the non-invasive measurement system of [16] accompanying known SOAE (for human), but without success. At present we believe this is because of its small amplitude in non-invasive measurement rather than its absence.…”

Section: -4mentioning

confidence: 99%

Model based prediction of the existence of the spontaneous cochlear microphonic

Ayat¹,

Teal²

2015

AIP Conference Proceedings

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The relation between tympanic membrane higher order modes and standing waves AIP Conference Proceedings 1703, 060008 (2015) Abstract. In the mammalian cochlea, self-sustaining oscillation of the basilar membrane in the cochlea can cause vibration of the ear drum, and produce spontaneous narrow-band air pressure fluctuations in the ear canal. These spontaneous fluctuations are known as spontaneous otoacoustic emissions. Small perturbations in feedback gain of the cochlear amplifier have been proposed to be the generation source of self-sustaining oscillations of the basilar membrane. We hypothesise that the selfsustaining oscillation resulting from small perturbations in feedback gain produce spontaneous potentials in the cochlea. We demonstrate that according to the results of the model, a measurable spontaneous cochlear microphonic must exist in the human cochlea. The existence of this signal has not yet been reported. However, this spontaneous electrical signal could play an important role in auditory research. Successful or unsuccessful recording of this signal will indicate whether previous hypotheses about the generation source of spontaneous otoacoustic emissions are valid or should be amended. In addition according to the proposed model spontaneous cochlear microphonic is basically an electrical analogue of spontaneous otoacoustic emissions. In certain experiments, spontaneous cochlear microphonic may be more easily detected near its generation site with proper electrical instrumentation than is spontaneous otoacoustic emission.

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“…• Electrocardiography (ECG) -action potentials of the heart • Electroencephalography (EEG) -action potentials of neurons • Electromyography (EMG) -action potentials of the muscles • Electrocochleography (ECochG) -action potentials of the auditory nerve These bio-potentials are typically measured at the surface of the body, apart from the ECochG of which non-invasive measurement is still being developed (Masood et al, 2012).…”

Section: Contact Sensorsmentioning

confidence: 99%

“…Natural and manmade sources contribute to a complex field spanning the entire frequency spectrum. Human bio-potentials range in amplitude from < 1µV for ECochG (Masood et al, 2012) to >10mV for EMG (Webster, 1999), and span frequencies from DC for EOG to 4kHz (Poch-Broto et al, 2009) and higher for ECochG. A device which is sensitive enough to measure these bio-potentials is also sensitive to other electric potentials such as; the mains power supply, 50Hz and harmonics; digital electronics, a wide range of frequencies dependant on slope of pulses; power switching transients such as room lighting or appliances, pulses containing a wide range of frequencies; and moving electrostatic potentials such as static build up on patients, generally low frequency (Putten, 1996).…”

Section: Shielding Guarding and Groundingmentioning

confidence: 99%

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High Impedance Amplifiers for Non-Contact Bio-Potential Sensing

Ryan¹

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<p>This research develops a non-contact bio-potential sensor which can quickly respond to input transient events, is insensitive to mechanical disturbances, and operates with a bandwidth from 0.04Hz – 20kHz, with input voltage noise spectral density of 200nV / √Hz at 1kHz. Initial investigations focused on the development of an active biasing scheme to control the sensors input impedance in response to input transient events. This scheme was found to significantly reduce the settling time of the sensor; however the input impedance was degraded, and the device was sensitive to distance fluctuations. Further research was undertaken, and a circuit developed to preserve fast settling times, whilst decreasing the sensitivity to distance fluctuations. A novel amplifier biasing network was developed using a pair of junction field effect transistors (JFETs), which actively compensates for DC and low frequency interference, whilst maintaining high impedance at signal frequencies. This biasing network significantly reduces the settling time, allowing bio-potentials to be measured quickly after sensor application, and speeding up recovery when the sensor is in saturation. Further work focused on reducing the sensitivity to mechanical disturbances even further. A positive feedback path with low phase error was introduced to reduce the effective input capacitance of the sensor. Tuning of the positive feedback loop gain was achieved with coarse and fine control potentiometers, allowing very precise gains to be achieved. The sensor was found to be insensitive to distance fluctuations of up to 0.5mm at 1Hz, and up to 2mm at 5kHz. As a complement to the non-contact sensor, an amplifier to measure differential bio-potentials was developed. This differential amplifier achieved a CMRR of greater than 100dB up to 10kHz. Precise fixed gains of 20±0:02dB, 40±0:01dB, 60±0:03dB, and 80±0:3dB were achieved, with input voltage noise density of 15nV / √Hz at 1kHz.</p>

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A non-invasive Cochlear Microphonic measurement system

Cited by 7 publications

References 10 publications

Modelling Cochlear Mechanics

Modelling Cochlear Mechanics

Model based prediction of the existence of the spontaneous cochlear microphonic

High Impedance Amplifiers for Non-Contact Bio-Potential Sensing

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