Acoustic Measurements of Objective Tinnitus

1990 ◽  
Vol 33 (4) ◽  
pp. 816-821 ◽  
Author(s):  
Craig A. Champlin ◽  
Stephen P. Muller ◽  
Stephen A. Mitchell
Keyword(s):  
Jugular Vein ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Masking Effect ◽  
Hearing Sensitivity ◽  
Normal Limits ◽  
Objective Tinnitus ◽  
Low Pass ◽  
Vascular Origin ◽  
One Year

Ear canal sound pressure levels were measured from a 38-year-old woman who had experienced objective tinnitus in her right ear for approximately 2 years. The tinnitus sounded like a series of “sighs” that were synchronous with her pulse rate. Because the level of the tinnitus fluctuated in a pulsing manner, it appeared to be of vascular origin. Psychoacoustically, the tinnitus behaved like a low-pass masker (cutoff frequency = 1.5 kHz) of about 40 dB SPL. This masking effect was manifested as a low-frequency hearing loss in the subject’s right ear. A miniature microphone system was used to monitor the tinnitus before, during, and after a jugular-vein ligation. Because the cause of the tinnitus was only generally known, acoustically monitoring the sound as the jugular vein and/or its tributaries were systematically clamped and then released enabled the site of generation to be known exactly. By monitoring the tinnitus during surgery, the effectiveness of the corrective procedure could be immediately evaluated. Hearing sensitivity in the affected ear returned to normal limits following the elimination of the tinnitus. One year after the surgery, the tinnitus was barely audible to the woman, but only when she positioned her head a specific way. The level of the tinnitus measured in this head-turned condition was markedly lower than the level obtained preoperatively.

A Low-Frequency Filter in Inertial Applications

2015 ◽  
Vol 645-646 ◽  
pp. 875-880
Author(s):  
Qiang Li ◽  
Xiao Wei Liu ◽  
Liang Yin ◽  
Jia Jun Zhou
Keyword(s):  
Large Time ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
Frequency Filter ◽  
Time Constants ◽  
Operational Transconductance Amplifiers ◽  
Technical Requirements ◽  
Low Pass ◽  
Transconductance Amplifiers ◽  
Current Shunt

A fourth-order cascade low-pass transconductance capacitor filter is designed, and the coefficients of the filter are calculated. For the implementation of large-time constants the current shunt technique and the current cancellation technique are employed in the operational transconductance amplifiers. The whole filter is simulated in Hspice, the the cutoff frequency is 150.2Hz and the THD of the filter is 65dB, which meet the technical requirements of the inertial applications.

Nonlinear inversion of gravity data using the Schmidt‐Lichtenstein approach

Geophysics ◽  
1987 ◽  
Vol 52 (1) ◽  
pp. 88-93 ◽  
Author(s):  
Harald Granser
Keyword(s):  
Power Series ◽  
Gravity Anomaly ◽  
Series Expansion ◽  
Gravity Data ◽  
Inverse Operator ◽  
Cutoff Frequency ◽  
Power Series Expansion ◽  
Low Frequency ◽  
Nonlinear Inversion ◽  
Low Pass

The nonlinear inversion of the gravity from a single density interface can be performed through a power series expansion. The method is based on the Schmidt‐Lichtenstein approach for solving nonlinear integral equations. After expanding the nonlinear integral operator for the gravity effect as an operator power series, the inverse operator series is found by applying a technique formally equivalent to the classical inversion scheme of a scalar power series. Unlike the forward power series expansion, however, the convergence of the inverse series is restricted to a low‐frequency domain, characterized by a cutoff frequency that is dependent upon the amplitude of the gravity anomaly, the magnitude of the density contrast, and the mean depth of the interface. To ensure the stability of the inversion scheme, a suitable low‐pass filtering has to be performed. By taking advantage of the noniterative nature of the inversion scheme and the fast Fourier transform, the method is efficiently applied to invert a profile‐like, simulated model and a 3-D field example (the Malcov gravity anomaly) caused by a small sedimentary basin in the East Slovakian Outer Carpathians.

The Dynamics of Integrate-and-Fire: Mean Versus Variance Modulations and Dependence on Baseline Parameters

2011 ◽  
Vol 23 (5) ◽  
pp. 1234-1247 ◽  
Author(s):  
Joanna Pressley ◽  
Todd W. Troyer
Keyword(s):  
Firing Rate ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
High Frequencies ◽  
Integrate And Fire ◽  
Poisson Input ◽  
Low Pass ◽  
Mean And Variance ◽  
The Mean ◽  
Frequency Modulations

The leaky integrate-and-fire (LIF) is the simplest neuron model that captures the essential properties of neuronal signaling. Yet common intuitions are inadequate to explain basic properties of LIF responses to sinusoidal modulations of the input. Here we examine responses to low - and moderate-frequency modulations of both the mean and variance of the input current and quantify how these responses depend on baseline parameters. Across parameters, responses to modulations in the mean current are low pass, approaching zero in the limit of high frequencies. For very low baseline firing rates, the response cutoff frequency matches that expected from membrane integration. However, the cutoff shows a rapid, supralinear increase with firing rate, with a steeper increase in the case of lower noise. For modulations of the input variance, the gain at high frequency remains finite. Here, we show that the low-frequency responses depend strongly on baseline parameters and derive an analytic condition specifying the parameters at which responses switch from being dominated by low versus high frequencies. Additionally, we show that the resonant responses for variance modulations have properties not expected for common oscillatory resonances: they peak at frequencies higher than the baseline firing rate and persist when oscillatory spiking is disrupted by high noise. Finally, the responses to mean and variance modulations are shown to have a complementary dependence on baseline parameters at higher frequencies, resulting in responses to modulations of Poisson input rates that are independent of baseline input statistics.

Hilbert low-pass filter of non-stationary time sequence using analytical mode decomposition

2015 ◽  
Vol 23 (15) ◽  
pp. 2444-2469 ◽  
Author(s):  
Zuo-Cai Wang ◽  
Yu Xin ◽  
Jin-feng Xing ◽  
Wei-Xin Ren
Keyword(s):  
Cutoff Frequency ◽  
Low Frequency ◽  
Frequency Component ◽  
Sampling Frequency ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Mode Decomposition ◽  
Low Pass ◽  
One Step ◽  
Low Pass Filters

In this paper, the recently developed analytical mode decomposition with a constant or time-varying cutoff frequency is extended into the decomposition of a non-stationary discrete time sequence. The discretization of the signal and the selection of the cutoff frequency may cause the failure of low frequency component extraction. In this study, to eliminate the effects of the signal discretization, the one-step, two-step, and four-step low-pass filters with cutoff frequencies are proposed. Based on the theoretical derivation, the previous one-step low-pass filter is effective only when the cutoff frequency is not greater than a quarter of the sampling frequency and the maximum frequency of the signal not greater than a half of the sampling frequency. In this study, if the cutoff frequency is less than or equal to a quarter of the sampling frequency, a two-step low-pass filter is proposed to extract the low frequency component. If the cutoff frequency is greater than a quarter of the sampling frequency, a four-step low-pass filter with frequency shifting process is proposed. When the time-varying cutoff frequency is not always larger than or less than a quarter of the sampling frequency, a sufficient condition, which is the sampling frequency is greater than four times of the maximum frequency of the signal component, is provided in this study. Two numerical examples are used to validate the effectiveness of the proposed low-pass filters. Both the theoretic derivation and numerical simulations show that the proposed filters can analytical extract the discrete low frequency component with an appropriate cutoff frequency.

scholarly journals 1.0 V-0.18 µm CMOS Tunable Low Pass Filters with 73 dB DR for On-Chip Sensing Acquisition Systems

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 563
Author(s):  
Jorge Pérez-Bailón ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Power Consumption ◽  
Dynamic Range ◽  
Low Voltage ◽  
Cutoff Frequency ◽  
Cmos Technology ◽  
Active Area ◽  
Current Steering ◽  
Low Pass ◽  
On Chip ◽  
Low Pass Filters

This paper presents a new approach based on the use of a Current Steering (CS) technique for the design of fully integrated Gm–C Low Pass Filters (LPF) with sub-Hz to kHz tunable cut-off frequencies and an enhanced power-area-dynamic range trade-off. The proposed approach has been experimentally validated by two different first-order single-ended LPFs designed in a 0.18 µm CMOS technology powered by a 1.0 V single supply: a folded-OTA based LPF and a mirrored-OTA based LPF. The first one exhibits a constant power consumption of 180 nW at 100 nA bias current with an active area of 0.00135 mm2 and a tunable cutoff frequency that spans over 4 orders of magnitude (~100 mHz–152 Hz @ CL = 50 pF) preserving dynamic figures greater than 78 dB. The second one exhibits a power consumption of 1.75 µW at 500 nA with an active area of 0.0137 mm2 and a tunable cutoff frequency that spans over 5 orders of magnitude (~80 mHz–~1.2 kHz @ CL = 50 pF) preserving a dynamic range greater than 73 dB. Compared with previously reported filters, this proposal is a competitive solution while satisfying the low-voltage low-power on-chip constraints, becoming a preferable choice for general-purpose reconfigurable front-end sensor interfaces.

scholarly journals Earless toads sense low frequencies but miss the high notes

2017 ◽  
Vol 284 (1864) ◽  
pp. 20171670 ◽  
Author(s):  
Molly C. Womack ◽  
Jakob Christensen-Dalsgaard ◽  
Luis A. Coloma ◽  
Juan C. Chaparro ◽  
Kim L. Hoke
Keyword(s):  
High Frequency ◽  
Species Differences ◽  
Low Frequency ◽  
Auditory Brainstem ◽  
Low Frequencies ◽  
Hearing Sensitivity ◽  
Sensory Pathways ◽  
Airborne Sound ◽  
Vibrational Sensitivity ◽  
Species Specific

Sensory losses or reductions are frequently attributed to relaxed selection. However, anuran species have lost tympanic middle ears many times, despite anurans' use of acoustic communication and the benefit of middle ears for hearing airborne sound. Here we determine whether pre-existing alternative sensory pathways enable anurans lacking tympanic middle ears (termed earless anurans) to hear airborne sound as well as eared species or to better sense vibrations in the environment. We used auditory brainstem recordings to compare hearing and vibrational sensitivity among 10 species (six eared, four earless) within the Neotropical true toad family (Bufonidae). We found that species lacking middle ears are less sensitive to high-frequency sounds, however, low-frequency hearing and vibrational sensitivity are equivalent between eared and earless species. Furthermore, extratympanic hearing sensitivity varies among earless species, highlighting potential species differences in extratympanic hearing mechanisms. We argue that ancestral bufonids may have sufficient extratympanic hearing and vibrational sensitivity such that earless lineages tolerated the loss of high frequency hearing sensitivity by adopting species-specific behavioural strategies to detect conspecifics, predators and prey.

Design and Simulation of Switched Capacitor Filter for Speed Change Parameter Converter

2013 ◽  
Vol 562-565 ◽  
pp. 1132-1136
Author(s):  
Xiao Wei Liu ◽  
Jian Yang ◽  
Song Chen ◽  
Liang Liu ◽  
Rui Zhang ◽  
...  
Keyword(s):  
Stop Band ◽  
Cutoff Frequency ◽  
Rapid Change ◽  
Pass Band ◽  
Cmos Process ◽  
Switched Capacitor ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass ◽  
The Time Domain

In this paper, we design a high-order switched capacitor filter for rapid change parameter converter. This design uses a structure which consists of three biquads filter sub-units. The design is a 6th-order SC elliptic low-pass filter, and the sample frequency is 250 kHz. By the MATLAB Simulink simulation, the system can meet the design requirements in the time domain. In this paper, the 6th-order switched capacitor elliptic low-pass filter was implemented under 0.5 um CMOS process and simulated in Cadence. The final simulation results show that the pass-band cutoff frequency is 10 kHz, and the maximum pass-band ripple is about 0.106 dB. The stop-band cutoff frequency is 20 kHz, and the minimum stop-band attenuation is 74.78 dB.

scholarly journals Recovery from Transient Global Amnesia Following Restoration of Hippocampal and Fronto–Cingulate Perfusion

2010 ◽  
Vol 22 (3-4) ◽  
pp. 131-139 ◽  
Author(s):  
Paolo Caffarra ◽  
Letizia Concari ◽  
Simona Gardini ◽  
Sabrina Spaggiari ◽  
Francesca Dieci ◽  
...  
Keyword(s):  
Acute Phase ◽  
Neuropsychological Testing ◽  
Transient Global Amnesia ◽  
Normal Limits ◽  
Global Amnesia ◽  
One Year ◽  
The Right ◽  
Rcbf Spect ◽  
Subject Comparison

A patient who suffered a transient global amnesia (TGA) attack underwent regional cerebral blood flow (rCBF) SPECT imaging and neuropsychological testing in the acute phase, after one month and after one year. Neuropsychological testing in the acute phase showed a pattern of anterograde and retrograde amnesia, whereas memory was within age normal limits at follow up. SPECT data were analysed with a within subject comparison and also compared with those of a group of healthy controls. Within subject comparison between the one month follow up and the acute phase detected increases in rCBF in the hippocampus bilaterally; further rCBF increases in the right hippocampus were detected after one year. Compared to controls, significant hypoperfusion was found in the right precentral, cingulate and medial frontal gyri in the acute phase; after one month significant hypoperfusion was detected in the right precentral and cingulate gyri and the left postcentral gyrus; after one year no significant hypoperfusion appeared. The restoration of memory was paralleled by rCBF increases in the hippocampus and fronto-limbic-parietal cortex; after one year neither significant rCBF differences nor cognitive deficits were detectable. In conclusion, these data indicate that TGA had no long lasting cognitive and neural alterations in this patient.

Acoustics of Sound Production and of Hearing in the Bladder Cicada Cystosoma Saundersii (Westwood)

1978 ◽  
Vol 72 (1) ◽  
pp. 43-55 ◽  
Author(s):  
N.H. FLETCHER ◽  
K. G. HILL
Keyword(s):  
Sound Production ◽  
Abdominal Cavity ◽  
Low Frequency ◽  
Sound Intensity ◽  
Electrical Network ◽  
Directional Hearing ◽  
Hearing Sensitivity ◽  
Physical Mechanisms ◽  
Radiated Sound ◽  
Song Frequency

The male cicada of the species Cystosoma saundersii has a grossly enlarged, hollow abdomen and emits a loud calling song with a fundamental frequency of about 800 Hz. At the song frequency, its hearing is nondirectional. The female of C. saundersii lacks sound producing organs, has no enlargement of the abdomen, but possesses an abdominal air sac and has well developed directional hearing at the frequency of the species' song. Physical mechanisms are proposed that explain these observations in semi-quantitative detail using the standard method of electrical network analogues. The abdomen in the male, with its enclosed air, is found to act as a system resonant at the song frequency, thus contributing a large gain in radiated sound intensity. Coupling between this resonator and the auditory tympana accounts for the observed hearing sensitivity in the male, but destroys directionality. In the female, the abdominal cavity acts in association with the two auditory tympana as part of a phase shift network which results in appreciable directionality of hearing at the unusually low frequency of the male song.

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