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Results for “Auditory Threshold”

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At least 253 records · Page 14Linked to original sources

PubMed1981

[Temporary shift in the auditory threshold of lumberjacks working with mechanized saws].

The audiometric examinations of motor-sawers exposed to intermittent noise at a level of 98-112 dB (A) for 1-4 hrs daily indicated hearing losses. An index of the potential hearing impairment risk induced by noise is a temporary hearing threshold shift due to that noise exposure. The studies showed not a single temporary hearing threshold shift in motor-sawers after a daily exposure to the saw noise, which implies that the noise does not immediately affect the hearing organ.

Adult↗

PubMed1989

Aided auditory thresholds in children with postmeningitic deafness.

Postmeningitic hearing loss is often bilateral, profound, and rapid in onset. Children with postmeningitic hearing loss may be identified as potential candidates for cochlear implantation. The length of time required for a definitive trial with conventional amplification, which must precede a final decision regarding cochlear implant surgery, has been the subject of debate. Twenty-five children with bilateral severe-to-profound postmeningitic sensorineural hearing loss were fitted with appropriate amplification and results of serial-aided tests were analyzed to determine the degree of benefit and changes in aided thresholds over time. Twelve children gave aided responses that clearly indicated the presence of residual hearing and good aided benefit. Ten youngsters have responded consistently in the vibrotactile range when aided, thus receiving limited benefit from conventional amplification. Of particular interest are three children who initially exhibited limited or no auditory responses but who, after a period of 16 to 25 months, showed excellent benefit with binaural hearing aids. These children are all in total communication programs and have received good auditory training. Caution should be exercised when concluding that such a child does not benefit from amplification.

Audiometry, Evoked Response↗

PubMed1980

[Evaluation of the degree of temporary shift in auditory threshold at extended high-frequencies in relation to the efficiency of the organ of hearing].

Temporary threshold shift measurements were taken at extended high frequencies range up to 20 kHz after the first day of work at noise (TTSI) and after a week of work (TTSII) at permanent noise exceeding allowable standards. 87 workers of the "Baildon" steel mill in Katowice were examined. The audiometric threshold examination was carried out after a 40-hr lay-off. Altogether 522 audiograms were done, yielding 4872 results. TTS magnitude was followed as dependent on the hearing organ functioning. TTS increase was found to be reversely dependent on the P.P. threshold values set up prior to noise exposure. The study of the temporary threshold shift for P.P. at extended range of higher frequencies is useful in the prevention of acoustic trauma, especially when meaning the selection of those oversusceptible to noise.

Adult↗

PubMedDate not supplied

Development of absolute auditory thresholds in the house mouse (Mus musculus).

The development of hearing in the house mouse (Mus musculus) was behaviorally tested from the first postnatally measurable thresholds to those of young adults. An unconditioned stop reaction on tones was used in 9- to 11-day-old mice, then an unconditioned pinna reflex that can be elicited at low intensities and is not equal to the Preyer reflex. In addition, thresholds from 17- to 19-day-old and adult mice were obtained by a conditioned eyelid reflex. Frequencies between 1 and 80 kHz were tested. First reactions on tones were found at day 10 after birth in the frequency range of greatest sensitivity in the adults (10-20 kHz). The sensitivity optimum at 15 kHz becomes evident at day 14. Up to day 15 a sensitivity increase is noticeable for frequencies below the optimum, whereas high frequency sensitivity increases up to day 18. A second maximum of sensitivity at 50 kHz is measurable in 2- to 3-month-old mice, the threshold curve of which is defined as the standard for Mus musculus. The present behavioral data can well be correlated with existing electrophysiological results in mice and rats.

Acoustic Stimulation↗

PubMedDate not supplied

A method for determining cortical auditory thresholds in guinea pigs.

A method for measuring evoked cortical potentials to acoustic stimuli through the intact dura mater of the guinea pig without computer averaging studied. After exposure of the dura overlying the auditory cortex on the left side, thresholds to acoustic stimuli presented to the right ear were determined with a double tipped silver electrode by visual detection on an oscilloscope. The thresholds obtained are compared with other methods of determining audibility levels in the guinea pig. With relatively simple instrumentation, this method provides rapid and accurate determination of the audibility curve.

Acoustic Stimulation↗

PubMed1988

[Evaluation of the effect of auditory fatigue on the human ear based on the measurement of brain stem auditory potentials (ABR). II. Relation of temporary auditory threshold shift and changes in the latency of wave V].

The relationship between temporary threshold shift (TTS) and latency changes of auditory brainstem responses (ABR) induced by noise exposure was studied in 23 normal-hearing subjects. Shift in latency wave V at 40 dB nHL of stimulus intensity as a result of auditory fatigue showed no significant correlation with TTS at 4 kHz. The great intersubject variability of shifts in latency wave V as a result of auditory fatigue suggests that this shift may be a useful measure of individual susceptibility to noise.

Acoustic Stimulation↗

PubMed2004

Towards a unifying basis of auditory thresholds: the effects of hearing loss on temporal integration reconsidered.

For signal detection and identification, the auditory system needs to integrate sound over time. It is frequently assumed that the quantity ultimately integrated is sound intensity and that the integrator is located centrally. However, we have recently shown that absolute thresholds are much better specified as the temporal integral of the pressure envelope than of intensity, and we proposed that the integrator resides in the auditory pathway's first synapse. We also suggested a physiologically plausible mechanism for its operation, which was ultimately derived from the specific rate of temporal integration, i.e., the decrease of threshold sound pressure levels with increasing duration. In listeners with sensorineural hearing losses, that rate seems reduced, but it is not fully understood why. Here we propose that in such listeners there may be an elevation in the baseline above which sound pressure is effective in driving the system, in addition to a reduction in sensitivity. We test this simple model using thresholds of cats to stimuli of differently shaped temporal envelopes and durations obtained before and after hearing loss. We show that thresholds, specified as the temporal integral of the effective pressure envelope, i.e., the envelope of the pressure exceeding the elevated baseline, behave almost exactly as the lower thresholds, specified as the temporal integral of the total pressure envelope before hearing loss. Thus, the mechanism of temporal integration is likely unchanged after hearing loss, but the effective portion of the stimulus is. Our model constitutes a successful alternative to the model currently favored to account for altered temporal integration in listeners with sensorineural hearing losses, viz., reduced peripheral compression. Our model does not seem to be at variance with physiological observations and it also qualitatively accounts for a number of phenomena observed in such listeners with suprathreshold stimuli.

Animals↗

PubMedDate not supplied

[High-frequency audiometry: variations in auditory thresholds in the premenstrual period].

The hormonal changes that occur during the premenstrual period have been implicated as a causative factor for many psychological and physical symptoms. The present work was undertaken to determine the effect of these hormonal changes on audition. We studied 60 ears from 30 women (20-30 years old) with regular menstrual cycles and no middle/inner ear pathology. We performed audiometries one week before menstruation and one week after it, testing the range of frequencies from 250 to 16,000 Hz. After calculating the mean pre and postmenstrual threshold the results were compared using the paired < >-Student test. We found statistical significant differences in the frequencies 9,000, 10,000 and 11,200 Hz.

Adult↗

PubMedDate not supplied

Influence of cigarette smoking on extra-high-frequency auditory thresholds.

Twenty-five young adult nonsmokers and 18 smokers were studied with respect to differences in their extra-high-frequency (EHF) auditory sensitivity. Although no statistically significant differences were found between their EHF thresholds, there was some evidence that smokers have poorer EHF hearing. The implication of this finding, vis-à-vis the use of EHF auditometry as a predictor of atheromatous damage to blood vessel walls, is discussed with suggestions for future research.

Adult↗

PubMed2001

Signal detection in amplitude-modulated maskers. I. Behavioural auditory thresholds in a songbird.

Vertebrates have evolved mechanisms to exploit amplitude modulations in background noise for improving signal detection. However, the mechanisms underlying this masking release are not yet well understood. Here we present evidence for masking release observed in European starlings (Sturnus vulgaris, Aves) that were trained in a Go/NoGo paradigm to report the detection of a short tone (20 ms) in 100% sinusoidally amplitude-modulated noise maskers (400 ms duration). Maskers centred at the tone frequency were composed of one, three, or five spectrally adjacent noise bands each of auditory filter bandwidth. Envelopes of the masking noise bands were either in-phase (i.e. coherent) or successively phase shifted by 90 degrees (i.e. incoherent). A release from masking of up to 28 dB was observed for detection of signals presented in dips of the envelope of coherent maskers compared with those presented in peaks of coherent maskers and in incoherent maskers. For maskers limited to one auditory filter (i.e. limited to the analysis channel tuned to the test signal) this masking release was about 10 dB less than that observed for maskers allowing a comparison across three or five auditory filters. This indicates that both within-channel cues and across-channel cues are important for signal detection. These behavioural data provide the reference for the study of responses of auditory forebrain neurons in the same species reported in a companion paper [Nieder & Klump (2001) Eur. J. Neurosci., 13, 1033-1044].

Animals↗

PubMed1994

Auditory threshold evaluation by distortion-product oto-acoustic emissions using decision support system.

Distortion-product oto-acoustic emissions (DPOEs) were measured in 102 normal-hearing and hearing-impaired ears to examine the sensibility, specificity, positive predictive value and negative predictive value of this test in a real clinical setting using two decision support systems. The first model only considered the presence or the absence of DPOEs in response to a 52 dB SPL stimulation intensity. The second model used two consecutive tests: i) the presence or the absence of DPOEs in response to a 52 dB SPL stimulation intensity, and ii) evaluation of the slope of each DPOE input-output function. The sensitivity of these two models varied between 1 and 0.83 whereas the specificity varied between 0.95 and 0.72 as a function of the frequency tested. The first model proved to be a very sensitive test, but the introduction of a second criterion of decision (i.e., the slope of DPOE input-output function) did not enhance the validity of the test.

Acoustic Stimulation↗

PubMed1993

Mice heterozygous for the deafness gene have normal auditory thresholds.

Cochlear degeneration in the early postnatal period has been reported as a homozygous recessive mutation in deafness (dn/dn) mice of the curly-tail stock. Heterozygous (+/dn) mice of the same population exhibit hearing when tested by the Preyer reflex, and their cochlear morphology appears normal by light microscopy. However, whether the heterozygote's unmatched recessive deafness allele has deleterious effects not detected by this reflex has not been examined. This study compares the ABR thresholds of presumed homozygous dominant (+/+) and known heterozygous (+/dn) deafness mice, as well as CBA/J mice. Hearing thresholds in the heterozygotes were not significantly different from those of presumed homozygotes or CBA/J mice. A 'generational backtracking' method was used to increase the probability of identifying homozygous (+/+) animals of the curly-tail strain.

Alleles↗

PubMedDate not supplied

[Bone conduction receiver for the measurement of the auditory thresholds over a broad frequency range].

A piesoelectric bony telephone for determining audible thresholds while sound is conducted through the bone over expanded frequency range of 0.25 kHz up to 20.0 kHz is described. Fundamental limitations of electromagnetic bony telephones preventing them from metering audible thresholds at the frequencies greater than 6 kHz have been revealed. Analysis of the piesoelectric transducer equivalent circuit has demonstrated on principle the possibility to measure audible thresholds with such a device over the expanded frequency range to 20 kHz. A model of piesoelectric bony telephone conforming the IEC recommendations is described and some experimental results obtained for the frequency range of 0.25 kHz to 20.0 kHz are presented.

Audiometry↗

PubMed1995

Behavioral auditory thresholds for sinusoidal electrical stimuli in the cat.

Behavioral thresholds were measured in four cats by training them to respond behaviorally to acoustic auditory stimuli using food as a reward in an operant reinforcement paradigm. Following training, the subjects were implanted unilaterally with either a scaled-UCSF electrode containing four contacts or an electrode array containing eight intracochlear contacts and one extracochlear contact under temporalis muscle. Behavioral thresholds for electrical stimuli were obtained as a function of sinusoidal frequency, duration, and electrode configuration. Threshold functions for both electrode types and all animals had minima between 48 and 125 Hz and, in general, were relatively flat below this minima; functions increased at 3-6 dB/octave from 96 Hz to 1 kHz. Threshold varied predictably as a function of electrode configuration, with thresholds decreasing as much as 20 dB as electrode spacing was widened from a radial bipolar (200-microns separation) to a monopolar configuration (apical stimulating and temporalis return). With long-duration stimuli, increasing the electrode separation systematically increased the slope of the threshold-versus-frequency contours in all animals. Irrespective of electrode type or configuration, charge/phase thresholds for single-cycle sinusoids were relatively flat for stimulus periods up to 1-5 ms, approximating a constant charge/phase determination of threshold. At phase durations greater than 5 ms, charge thresholds increased at a rate slightly above 6 dB/octave (constant peak current), which was suggestive of neural accommodation. Thresholds for the cat share many features with those reported for implanted humans and monkeys.

Acoustic Stimulation↗

PubMed1990

[The accuracy of subjective determination of auditory threshold in the range of 0.5 to 18.0 kHz using different sound transducer systems].

This paper reports on the degree of accuracy of determinations of hearing threshold in the 0.5 to 18 kHz range. As far as possible, these hearing thresholds were compared with those of ISO 389. Furthermore, the study compared determinations of hearing thresholds measured on different days. Reproducibility was very good, particularly of the high-frequency thresholds. The two types of sound transducers used here (a quasi-free field system developed by the authors and a pair of professional headphones) showed an identical transmission of frequencies and good reproducibility of the results of measurements.

Adult↗

PubMed1989

[Study of hearing in normally-hearing elderly patients. I. Auditory threshold].

Through this paper the AA. examine 504 ears of 252 subjects of both sexes, between 60 and 84, all feeling subjectively normal regarding this sense, without otologic conditions in the past or at present. The explorations done were air and bone tonal audiometry. At the time the results were assessed, the coefficient of variability and standard deviation were kept in mind.

Aged↗

PubMed1987

Strain differences in auditory thresholds in the canary (Serinus canarius).

Canaries (Serinus canarius) of the Belgian waterslager strain from two different colonies were trained with operant techniques for audiometric testing. For both young and old birds, absolute thresholds in the middle- to high-frequency region of the audiogram were between 30 and 40 dB (SPL) higher than those of other song birds, including canaries of other strains. Thus the Belgian waterslager canary, selectively bred for loud, low-pitched song, has also developed poor high-frequency hearing.

Aging↗

PubMed1992

Long-term measures of electrode impedance and auditory thresholds for the Ineraid cochlear implant.

Measures of electrode impedance and of detection thresholds for electrical stimuli were extracted from the records of patients implanted with the Ineraid cochlear prosthesis. An analysis of impedance measures, obtained at 1, 12, 24, and 36 months after surgery, demonstrated (a) a significant decrease in impedance over the first year for electrodes that carried current and (b) significant increases in impedance at 24 and 36 months for electrodes that did not carry current. An analysis of detection thresholds, obtained at the same times as the impedance measures, demonstrated that averaged thresholds for the current-carrying electrodes varied no more than 0.5 dB over the 3-year period. These results support the conclusion that stimulation with the Ineraid device does not produce deleterious changes in the electrodes or in the target neural tissue.

Acoustic Impedance Tests↗