Potentials around Electrode Tips with Implications for Cochlear Implants

1987 ◽  
Vol 96 (1_suppl) ◽  
pp. 21-22 ◽  
Author(s):  
G. Kauffmann ◽  
A. Achilles
Keyword(s):  
Electrical Properties ◽  
Cochlear Implants ◽  
Computer Model ◽  
High Frequency ◽  
Near Field ◽  
Far Field ◽  
Material Data ◽  
Low Pass ◽  
Frequency Components ◽  
Technical Material

Any presence of technical material (eg, metals) in biologic tissue alters the spread of potentials in it. We decided to investigate the spread of potentials around electrode tips using a computer model based on material data extracted from the literature. The following results were obtained. 1) The permittivity of the tissue caused a low pass effect. The potential lost its high frequency components as the distance to the electrode tip increased. An increase of the inner resistance of the source enhanced this effect. 2) The assumption of not constant but falling permittivity and rising conductivity with frequency still enlarged the effect and altered the resulting waveform because of the response of the affected electrical properties of the tissue on the spread of potentials. The latter effect was seen in the near field; in the far field (> 20 μm), it vanished progressively.

Far-Field Performances Prediction of High Frequency Projectors Using Secondary Source Array Method

2016 ◽  
Vol 25 (02) ◽  
pp. 1750002 ◽  
Author(s):  
Shiquan Wang
Keyword(s):  
High Frequency ◽  
Near Field ◽  
Directivity Pattern ◽  
Field Method ◽  
Voltage Response ◽  
Secondary Source ◽  
Far Field ◽  
Comparison Of The Results ◽  
Source Array ◽  
Good Agreement

This paper investigates the prediction of the far-field performances of high frequency projectors using the second source array method (SSAM). The far-field parameters can be calculated accurately using the complex acoustic pressure data of two very close parallel planes which lie in the near-field region of the projector. The paper simulates the feasibility of predicting the far-field parameters such as transmitting voltage response and the far-field directivity pattern. The predicting results are compared with that calculated using boundary element method (BEM). It shows very good agreement between the two methods. A planar high frequency projector is measured using the near-field method. In order to verify the predicting results, the far-field measurement is performed for the same projector. The comparison of the results shows that the near-field method is capable to precisely predict the far-field parameters of the projector.

scholarly journals Investigating Quick Speech-in-Noise Comprehension in Adult Bimodal Users

2021 ◽  
Author(s):  
Javad Fakhri ◽  
Nematollah Rouhbakhsh ◽  
Reza Hoseinabadi ◽  
Farzaneh Fatahi ◽  
Mahsa Sepehernejad ◽  
...  
Keyword(s):  
Cochlear Implants ◽  
High Frequency ◽  
Speech Comprehension ◽  
Signal To Noise ◽  
Average Percentage ◽  
Speech In Noise ◽  
Adult Participants ◽  
Frequency Components ◽  
The Right ◽  
Technological Limitations

Introduction: The use of cochlear implants, due to technological limitations, causes problems in speech comprehension in the presence of noise. This study aimed to evaluate the speech-in- noise (SIN) comprehension with emphasis on high-frequency components between users of different bimodal adult. Materials and Methods: This study was conducted on 33 adult participants with a mean age of 36 years using bimodal (cochlear implant in one ear and hearing aid in another ear: CI/HA) style of different companies. Quick SIN with emphasis on high-frequency components was performed on the participants using an audiometer, an amplifier, and one speaker. Results: Comparing the average percentage of correct answers from the word recognition test in the presence of noise in bimodal users showed that the Cochlear brand provides a better signal-to-noise (SNR) compare to other brands. Our result shows that bimodal users of Advance bionic and Med-El groups have better performance in speech recognition than other brands. Conclusion: Bimodal users of Advance bionic and Med-El have better SNR loss than other brands. Besides, further studies on different ages can be helpful to make the right decision in this regard.

Signature of coseismic off-fault damage in intermediate- and far-field radiation

2020 ◽  
Author(s):  
Kurama Okubo ◽  
Harsha S. Bhat ◽  
Esteban Rougier ◽  
Marine A. Denolle
Keyword(s):  
High Frequency ◽  
Near Field ◽  
Fault System ◽  
Far Field ◽  
Earthquake Rupture ◽  
Length Scales ◽  
Earthquake Sources ◽  
Planar Fault ◽  
Wide Range ◽  
Field Radiation

<p>Off-fault damage is observed around fault cores in a wide range of length scales, which is identified as an aggregation of localized fractures via geological and geodetic observations, or as low-velocity zone via seismological tomography. However, its seismological observables in earthquake traces, e.g. change in source spectra and/or radiation pattern, remains to be investigated. </p><p>Okubo et al. (2019) proposed an approach framework of physics-based dynamic earthquake rupture modeling with coseismic off-fault damage using the combined finite-discrete element method (FDEM). It shows a non-negligible contribution of coseismic damage to rupture dynamics, high-frequency radiation and overall energy budget, whereas the model domain is limited in the near-field region. This study efficiently computes intermediate- and far-field radiation propagating from earthquake sources with coseismic off-fault damage, and to identify its signature in the seismic traces.</p><p>We first conduct the dynamic earthquake rupture with coseismic damage and compute synthetic near-field radiation using FDEM-based software tool, HOSSedu, developed by Los Alamos National Laboratory. We then couple the output of HOSSedu to SPECFEM2D in order to compute intermediate- and far-field radiation. The HOSS-SPECFEM2D coupling can resolve complexities over wide range of length scales associated with earthquake sources with coseismic damage and wave propagation.</p><p>We conduct 2D dynamic earthquake rupture modeling with a finite planar fault as canonical simplest model. The comparison between the cases with and without allowing for coseismic off-fault damage shows differences in intermediate- and far-field radiation. 1) High-frequency components in ground motion are enhanced all around the fault. 2) The rupture arresting phase, which clearly appears at the stations located orthogonal to the fault for the case without off-fault damage, is damped due to the smoothed rupture arrest by coseismic damage around fault edges. 3) Radiated energy is enhanced in the direction parallel to the fault due to the substantial damage around fault edges.</p><p>These fundamental observables will help identify the existence of coseismic off-fault damage in real earthquakes. It would also contribute to resolve the mechanisms of earthquake sources and the potential distribution of aftershock locations. We also attempt to replace the planar fault to the real fault geometry, e.g. the fault system associated with the 2019 Ridgecrest earthquake sequence, and will investigate the signature of off-fault damage in the seismic traces recorded in intermediate- and far-field range.</p>

A modified Bessel filter for amplitude demodulation of respiratory electromyograms

1998 ◽  
Vol 84 (1) ◽  
pp. 378-388 ◽  
Author(s):  
Ronald S. Platt ◽  
Eric A. Hajduk ◽  
Manuel Hulliger ◽  
Paul A. Easton
Keyword(s):  
High Frequency ◽  
Stop Band ◽  
Pass Band ◽  
Third Order ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Transient Characteristics ◽  
Low Pass ◽  
Seventh Order ◽  
Frequency Components

Platt, Ronald S., Eric A. Hajduk, Manuel Hulliger, and Paul A. Easton. A modified Bessel filter for amplitude demodulation of respiratory electromyograms. J. Appl. Physiol. 84(1): 378–388, 1998.—We studied a device that is commonly used for amplitude demodulation of respiratory muscle electromyograms (EMG). This device contains a rectifier and a low-pass filter called a modified third-order Paynter filter. We characterized this filter and found that it has good transient characteristics that suit its task as an EMG demodulator, but it has poor high-frequency attenuation that passes interfering, higher frequency components to the output waveform. Therefore, we designed and constructed a new filter with transient characteristics that are comparable to those of the modified Paynter filter but with superior high-frequency attenuation. This new filter is a modified seventh-order Bessel filter. We also identified a simple technique to convert an existing modified Paynter filter back to an original Paynter filter. The original Paynter filter has a wider pass band than the modified Paynter filter but superior stop-band attenuation.

Speed of Processing and Stimulus Complexity in Low-Frequency and High-Frequency Channels

Perception ◽  
1997 ◽  
Vol 26 (8) ◽  
pp. 1039-1045 ◽  
Author(s):  
Rainer Hoeger
Keyword(s):  
High Frequency ◽  
Target Identification ◽  
Low Frequency ◽  
Object Perception ◽  
Stimulus Complexity ◽  
Frequency Information ◽  
Intensity Changes ◽  
Low Pass ◽  
Frequency Components ◽  
High Level

Studies of the microgenesis of perception led to the hypothesis that global aspects of objects are processed faster than their details. If one starts with the assumption that low-frequency information of objects corresponds to the global, and high-frequency information to the local aspects, recognising objects should rely at first on information from the low-frequency channels and afterwards from that of the high-frequency channels. The priming paradigm provides a mean of investigating experimentally the temporal availability of low-frequency and high-frequency information in object perception. In the experiments subjects had to respond to target objects preceded either by related or by unrelated priming stimuli, which consisted of low-pass-filtered and high-pass-filtered versions of the objects. With the influence of stimulus complexity controlled, pictures of objects were chosen that varied in the number of intensity changes in the high-frequency components, with those of the low-frequency components kept constant. The exposure duration of each prime was varied between 40 and 100 ms. The results indicated that target identification only profits more from low-frequency than from high-frequency primes if the high-frequency information has a high level of complexity. If the number of intensity changes in the high-frequency components of the prime is low, target identification is most strongly facilitated. The results are discussed in terms of models which focus on organising principles at different scales.

On a Design of Narrowband FIR Low-Pass Filters

2011 ◽  
pp. 2882-2887
Author(s):  
Gordana Jovanovic Dolecek ◽  
Javier Diaz Carmona
Keyword(s):  
Impulse Response ◽  
High Frequency ◽  
Digital Filters ◽  
Stop Band ◽  
Low Frequency ◽  
Pass Band ◽  
Low Pass ◽  
Frequency Components ◽  
Band Pass ◽  
High Pass

Stearns and David (1996) states that “for many diverse applications, information is now most conveniently recorded, transmitted, and stored in digital form, and as a result, digital signal processing (DSP) has become an exceptionally important modern tool.” Typical operation in DSP is digital filtering. Frequency selective digital filter is used to pass desired frequency components in a signal without distortion and to attenuate other frequency components (Smith, 2002; White, 2000). The pass-band is defined as the frequency range allowed to pass through the filter. The frequency band that lies within the filter stop-band is blocked by the filter and therefore eliminated from the output signal. The range of frequencies between the pass-band and the stop-band is called the transition band and for this region no filter specification is given. Digital filters can be characterized either in terms of the frequency response or the impulse response (Diniz, da Silva & Netto, 2002). Depending on its frequency characteristic, a digital filter is either low-pass, high-pass, band-pass, or band-stop filters. A low-pass (LP) filter passes low frequency components to the output, while eliminating high-frequency components. Conversely, the high-pass (HP) filter passes all high-frequency components and rejects all low-frequency components. The band-pass (BP) filter blocks both low- and high-frequency components while passing the intermediate range. The band-stop (BS) filter eliminates the intermediate band of frequencies while passing both low- and high-frequency components. In terms of their impulse responses digital filters are either infinite impulse response (IIR) or finite impulse response (FIR) digital filters. Each of four types of filters (LP, HP, BP, and BS) can be designed as an FIR or an IIR filter (Ifeachor & Jervis, 2001; Mitra, 2005; Oppenheim & Schafer, 1999).

Weaknesses of the Baxter-King Filter: Is a Pattern-Based Filter an Alternative? / Schwächen des Baxter-King Filters: Ist ein musterbasierter Filter eine Alternative?

2005 ◽  
Vol 225 (4) ◽  
Author(s):  
Georg Goldrian
Keyword(s):  
Time Series ◽  
High Frequency ◽  
Degree Of Approximation ◽  
Trigonometric Function ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Slow Moving ◽  
Ideal Filter

SummaryThe Baxter-King filter shows some weaknesses, particularly with regard to monthly time series. This procedure involves not only a loss of data for the border areas of time series, but suppresses inadequately high frequency components and shows as a low-pass filter only the performance of ordinary moving averages. Another important finding is that the maximal lag Κ not only determines the degree of approximation to an ideal filter, as Baxter and King argue, but also the ability to extract a slow moving component. A pattern-based filter, whose weights are generated by a trigonometric function as well, does not possess such weaknesses, and is thus a real alternative to the Baxter-King filter.

Frequency Modulated Empirical Mode Decomposition Method

2012 ◽  
Vol 433-440 ◽  
pp. 4776-4781
Author(s):  
Xin Zhang ◽  
Xiu Li Du
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Hilbert Huang Transform ◽  
Mode Decomposition ◽  
Empirical Mode Decomposition Method ◽  
Low Pass ◽  
Frequency Components ◽  
Band Pass ◽  
Stiffness And Damping ◽  
Mixing Problem

Frequency modulation procedure is proposed to overcome the mode-mixing problem associated with the EMD method when processing signals with closely spaced frequencies. This procedure also provides the flexibility to start the realization of IMFs either from the high frequency end as does the original EMD or from the low frequency end when the signal contains unwanted high frequency components. The EMD procedure, under the circumstances, may behave as high pass, low pass or band pass/stop filters. The proposed method, assisted by the Hilbert-Huang transform on the governing equations, identifies the instantaneous stiffness and damping coefficients as functions of vibration amplitude of a nonlinear system. The effectiveness of the proposed method is verified by numerical simulation.

Aliasing Effects on Nodal Acceleration Output From Nonlinear Finite Element Simulations

2000 ◽  
Author(s):  
Mark O. Neal ◽  
Chin-Hsu Lin ◽  
J. T. Wang
Keyword(s):  
Finite Element ◽  
High Frequency ◽  
Nonlinear Finite Element ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
Frequency Components ◽  
Averaging Filter ◽  
Very High ◽  
Acceleration Output

Abstract Nodal acceleration output from nonlinear finite element crash simulations often contains high frequency components. If this output is not sampled frequently enough the high frequency components will be aliased and the resulting acceleration output will be inaccurate. It is recommended in this paper that a low-pass filter be installed in the crashworthiness finite element codes which would remove the high frequency components of the nodal accelerations before they are sampled for output. This would completely eliminate aliasing error in acceleration output. Prior to this installation, there are several options for reducing the effects of aliasing on acceleration output. One option is to request very high sampling rates for acceleration output; however this will result in very large output files. Another option is to calculate the accelerations by differentiating the output velocities. This option, which effectively is an averaging filter acting on the accelerations, is available in the finite element code DYNA3D. The properties of this filter are examined in this paper and it is shown that this filter is very effective in reducing the effects of aliasing on acceleration output, although it should not be expected to completely eliminate potential aliasing problems. Finally, guidelines are presented for selecting nodes and sampling rates based on local natural frequencies that will reduce the effect of aliasing of the acceleration output.

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