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Results for “Auditory Threshold”

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PubMed1982

The threshold of sleep: perception of sleep as a function of time asleep and auditory threshold.

A number of studies have found that many subjects have reported being awake when awakened during various periods of electroencephalographically (EEG)-defined sleep. These observations have led to an examination of the perception of sleep after periods when EEG-defined sleep was experimentally varied between 1 and 140 min. Twelve normal young adult subjects slept in the laboratory for 5 consecutive nights. Each subject was briefly awakened five times on each night, and subjective state, auditory arousal threshold, and sleep/wake time estimation data were collected. The threshold of sleep onset (i.e., the point at which a report of sleep was given 50% of the time) occurred 2-4 min after the first sleep spindle. In contrast, auditory thresholds rose rapidly within 1 min of the first sleep spindle. The threshold data corroborate the appearance of a sleep spindle as an objective measure of sleep onset. However, subjective sleep onset appears to be a relatively lengthy period during which perception of state is blurred and uncertain.

Adolescent↗
PubMed1980

Age-dependence of the neural auditory thresholds of albino and pigmented guinea pigs.

Short-latency brain-stem responses of albino and pigmented guinea pigs were examined for evidence of age-dependence of the auditory threshold. Both groups exhibited a loss of hearing correlated with age. Moreover, albinos had significantly lower auditory thresholds than pigmented guinea pigs of the corresponding age group. A further difference between the two groups lay in the degree of which sensitivity declined with age; hearing loss in albinos was only about half that in pigmented animals.

Acoustic Stimulation↗
PubMed2004

Correlation of transiently evoked otoacoustic emission measures to auditory thresholds.

BACKGROUND: The presence of otoacoustic emissions is objective evidence of normal cochlear status. However, this test cannot be used to predict absolute auditory thresholds with accuracy. The criteria of normal otoacoustic emissions are not yet standardized and different measures of otoacoustic emissions have been used in various settings. In this study, the measures of reproducibility and otoacoustic emission amplitude are compared with regard to their correlation to pure-tone auditory (PTA) thresholds. MATERIAL/METHODS: One hundred and seventeen subjects with normal hearing were included in the study. Subjects with previous audiological, otolaryngologic, or vestibular disease were excluded. A complete ENT and audiological work-up was performed, including transiently evoked otoacoustic emissions (TEOAEs). The equipment used for TEOAE testing was a DP Echoport ILO 292 Otodynamics analyzer connected to a portable personal computer. A full 260 low-noise samples were averaged. Correlation between PTA thresholds and either overall TEOAE amplitude or whole reproducibility was estimated using multiple regression analysis. RESULTS: Correlation between acoustic thresholds at 250, 500, 1000, 2000, 4000 and 8000 Hz and either whole reproducibility or emission amplitude was highly significant for both measures. However, whole reproducibility was better correlated to acoustic thresholds at 250, 500, 1000, 2000, 4000 and 8000 Hz than was emission amplitude, and was more accurately predicted from multiple regression equations. CONCLUSIONS: Reproducibility measures performed better than TEOAE amplitude levels in the prediction of auditory thresholds.

Acoustic Stimulation↗
PubMed2003

Objective assessment of auditory thresholds in noise-induced hearing loss using steady-state evoked potentials.

The purpose of this study is to evaluate whether steady-state evoked potential (SSEP) can be used for objective estimation of auditory thresholds in patients with noise-induced hearing loss (NIHL). Eleven subjects (22 ears) with a characteristic audiometric notch between 3000 and 6000 Hz participated in this study. Both pure-tone thresholds and SSEP thresholds were obtained for each ear of all subjects. The correlation of SSEP thresholds and pure-tone thresholds was assessed. The results show that SSEP thresholds predicted pure-tone thresholds with correlation coefficients (r) of 0.86, 0.92, 0.94 and 0.95 at 500, 1000, 2000 and 4000 Hz respectively. Typically, the SSEP thresholds overestimate the pure-tone thresholds by 10-20 dB, but they closely reflect the configuration of the audiogram. The strength of the relationship between SSEP and pure-tone thresholds increased with increasing frequency and increasing degree of hearing loss. In conclusion, SSEP can be used as a reliable and objective tool to assess auditory thresholds in patients with noise-induced hearing loss with high-frequency dips.

Adult↗
PubMed1983

Sensation seeking, augmenting-reducing, and absolute auditory threshold: a strength-of-the-nervous-system perspective.

The following measures were obtained from 42 student volunteers: the General and the Disinhibition subscales of the Sensation Seeking Scale (Form IV), the Reducer-Augmenter Scale, and the Absolute Auditory Threshold. General sensation seeking correlated significantly with the Reducer-Augmenter Scale, r(40) = .59, p less than .001, and the Absolute Auditory Threshold, r(40) = .45, p less than .005. Both results proved general across sex. These findings, that high-sensation seekers tend to be reducers and to lack sensitivity to weak stimulation, were interpreted as supporting strength-of-the-nervous-system theory more than the formulation of Zuckerman and his associates.

Adolescent↗
PubMed1989

Ethanol's effects on auditory thresholds and reaction times during the acquisition of chronic ethanol self-administration in baboons.

Baboons were trained to ingest ethanol at successively higher ethanol concentrations using oral self-administration techniques. Concurrently, animal psychophysical procedures were employed to determine auditory thresholds and reaction times daily. Maximal consumption of ethanol occurred at concentrations of 6-8% (w/v). During the initial period of ethanol self-administration, both auditory reaction times and auditory thresholds became elevated as animals consumed larger amounts of ethanol. For both the threshold and reaction time measures, the degree of elevation was correlated with the amount of ethanol consumed. These correlations decreased, however, with continued ethanol consumption. The elevations in sensory and motor function recovered to near-baseline levels when ethanol was no longer available.

Animals↗
PubMed1967

Studies on auditory thresholds in normal man and in patients with adrenal cortical insufficiency: the role of adrenal cortical steroids.

Auditory thresholds for sinusoidal tones were determined in eight patients with adrenal cortical insufficiency (four with Addison's disease and four with panhypopituitarism) and compared to those in normal volunteers. In adrenal cortical insufficiency (ACI) the auditory detection sensitivity is significantly more acute than that of normal subjects over most of the frequency range, but especially in the region of greatest hearing sensitivity of normal subjects, 1,000 to 2,000 cycles per second (cps). Treatment of the patients with deoxycorticosterone acetate decreased serum potassium concentration and produced gains in body weight but did not alter auditory detection thresholds. Treatment with prednisolone or with maintenance doses of carbohydrateactive steroids returned the auditory detection threshold to normal in every patient tested.The mechanism by which carbohydrate-active steroids affect the sensitivity of the nervous system to sound is not known. However, since the senses of taste, smell, and hearing are all affected in similar fashion by their removal and replacement, there appears to be a generalized increase in sensitivity to all sensory stimuli in patients with ACI not receiving steroids. These hormones may play a significant role in maintaining the level of responsiveness of the sensory system to incoming stimuli.

Addison Disease↗
PubMed1986

Age categorization of high-frequency auditory threshold data.

This article presents high-frequency (8- to 20-kHz) auditory threshold measurements for 157 subjects with normal conventional hearing, ranging in age from 6-30 years. Normative descriptive data are provided in five semidecade age categories. Intra-age category mean and variance values for threshold sensitivity and interaural threshold differences are included. Generally, the data are consistent with the expectation of a gradual diminution of high-frequency sensitivity through the adolescent and early adult years. Several unresolved issues related to high-frequency normative data and clinical applicability of high-frequency threshold measurements are discussed.

Adolescent↗
PubMed1987

Hearing in passerine and psittacine birds: a comparative study of absolute and masked auditory thresholds.

Operant conditioning and a psychophysical tracking procedure were used to measure auditory thresholds for pure tones in quiet and in noise for seven species of small birds--the budgerigar, canary, cockatiel, European starling, song sparrow, swamp sparrow, and the zebra finch. Audibility curves are roughly similar among the seven birds, with the maximum sensitivity between 2 and 5 kHz and poorer sensitivity outside this narrow region. Critical ratios (signal-to-noise ratio at masked threshold) were calculated from pure-tone thresholds in noise. Except for the budgerigar, the critical ratio functions of all birds increase at the rate of 3 dB/octave. This pattern is typical of that observed in most vertebrates. Critical ratios in the budgerigar, on the other hand, decrease gradually from 0.5 kHz to 2.8 kHz and increase dramatically above 2.8 kHz. The present research demonstrates that the critical ratio function for the budgerigar is not only different from other vertebrates but also different from other birds.

Animals↗
PubMed2001

Effects of the Clarion Electrode Positioning System on auditory thresholds and comfortable loudness levels in pediatric patients with cochlear implants.

OBJECTIVE: To evaluate the effects of using the Electrode Positioning System on psychophysical auditory thresholds, most comfortable loudness levels, and electric auditory brainstem response (EABR) thresholds in children with the Clarion version 1.2 cochlear implant. DESIGN: Retrospective analysis. SETTING: Academic tertiary care center. PATIENTS AND METHODS: Clinical records of a series of 25 children who received the Clarion version 1.2 cochlear implant at the University of Minnesota, Minneapolis, between January 1997 and August 1999 were examined. Measures evaluated were psychophysical thresholds (T-levels) and most comfortable loudness levels (M-levels) obtained at the 3-month posthookup audiologic evaluation and EABR thresholds obtained during implant surgery. Relevant threshold measures were available for 24 patients, 11 of whom had received the Clarion spiral electrode and electrode positioner (EP group) and 13 of whom had received the spiral electrode without positioner (non-EP group). The 3 measures (T-levels, M-levels, and EABR thresholds) were compared across groups. In addition, EABR thresholds were compared with T-levels and M-levels within groups. RESULTS: Mean T-levels and M-levels were significantly lower for the EP group than for the non-EP group, and interpatient variability for these measures was considerably smaller in the EP group. Electric auditory brainstem response thresholds were not significantly different for EP vs non-EP patients; however, EABR data were available for only a few non-EP patients. CONCLUSIONS: Use of the electrode positioner results in lower T-levels and M-levels in children with the Clarion version 1.2 cochlear implant, consistent with results of previous studies in adults, and reduces across-patient variability for these measures. It is unclear from the present data whether use of the electrode positioner systematically reduces intraoperative EABR thresholds.

Auditory Threshold↗
PubMed2003

A unifying basis of auditory thresholds based on temporal summation.

Thresholds of auditory-nerve (AN) fibers and auditory neurons are commonly specified in terms of sound pressure only, implying that they are independent of time. At the perceptual level, however, the sound pressure required for detection decreases with increasing stimulus duration, suggesting that the auditory system integrates sound over time. The quantity commonly believed to be integrated is sound intensity, implying that the auditory system would have an energy threshold. However, leaky integrators of intensity with time constants of hundreds of milliseconds are required to fit the data. Such time constants are unknown in physiology and are also incompatible with the high temporal resolution of the auditory system, creating the resolution-integration paradox. Here we demonstrate that cortical and perceptual responses are based on integration of the pressure envelope of the sound, as we have previously shown for AN fibers, rather than on intensity. The functions relating the pressure envelope integration thresholds and time for AN fibers, cortical neurons, and perception in the same species (cat), as well as for perception in many different vertebrate species, are remarkably similar. They are well described by a power law that resolves the resolution-integration paradox. The data argue for the integrator to be located in the first synapse in the auditory pathway and we discuss its mode of operation.

Animals↗
PubMed1997

Auditory threshold sensitivity of the human neonate as measured by the auditory brainstem response.

The absolute auditory sensitivity of the human newborn infant was investigated using auditory brainstem response thresholds (ABR). ABRs were elicited with clicks and tone-bursts of 0.5, 1.5, 4.0 and 8.0 kHz, embedded in notched noise, in healthy, full-term human neonates and young adults with known, normal-hearing sensitivity. Stimuli were calibrated using a probe microphone positioned near the tympanic membrane in the ear canal of each subject to control for differences in resonance characteristics of infant and adult ear canals. ABR thresholds were also characterized relative to group psychophysical thresholds (nHL) and relative to individual psychophysical threshold or sensation level (SL) for the adult subjects. Infant ABR thresholds measured in p.e. SPL for all stimuli are elevated by to 3-25 dB relative to adult thresholds. Threshold elevation is greatest for the high-frequency stimuli. Result are consistent with neural immaturity for high-frequency stimuli in the auditory system of human neonates.

Acoustic Stimulation↗
PubMed2001

Effects of a 2- to 4-week course of repetitive transcranial magnetic stimulation (rTMS) on neuropsychologic functioning, electroencephalogram, and auditory threshold in depressed patients.

BACKGROUND: The safety of repetitive transcranial magnetic stimulation (rTMS) has only previously been formally studied in volunteers receiving a single session of stimulation or in a small number of depressed subjects receiving a 2-week treatment course. This study examined safety issues in depressed subjects receiving up to 4 weeks of rTMS. Efficacy results from this study have been previously reported. METHODS: Eighteen subjects with DSM-IV major depression participated in a 2-week, parallel, double-blind, sham-controlled study of rTMS treatment. Twelve subjects then went on to receive 4 weeks active rTMS in an open follow-up. We examined the effects of rTMS on neuropsychologic function (up to 4 weeks), auditory threshold (up to 6 weeks exposure to rTMS noise), and an electroencephalogram (after 2 weeks). Data were analyzed by repeated measures analysis. RESULTS: There were trends for improvement in neuropsychologic performance, probably due to practice effects. No mean changes in auditory threshold occurred, but two patients showed mild high-frequency hearing loss after several weeks of rTMS. Electroencephalograms in two patients, one of whom had sham stimulation, showed minor abnormality. CONCLUSIONS: No significant mean deficits were demonstrated in this cohort. Overall, rTMS for up to 4 weeks is safe, but individual results suggest caution and the need for further investigation of the safety of several weeks of rTMS.

Adult↗
PubMed1978

The influence of middle-ear muscle contraction on auditory threshold for selected pure tones.

The influence of middle-ear muscle (MEM) contraction on auditory threshold has been measured for pure tones of 0.25, 0.5, and 1.5 kHz. The reflex-activating signal was a 3-kHz pure tone. Signal paradigms were chosen to reduce or eliminate the effects of binaural loudness summation, contralateral direct masking, and contralateral remote and backward masking effects, and to maximize the influence of MEM contraction. Results indicate that under no condition was behavioral threshold affected by the MEM contraction induced using a pure-tone stimulus of 3 kHz, 105 dB SPL.

Adult↗
PubMed1987

Cryoprobe-induced apical lesions in the chinchilla. II. Effects on behavioral auditory thresholds.

Lesions of the hair cells in the cochlear apex were produced by a miniature cryoprobe and changes in behavioral auditory thresholds were measured. Monauralized adult chinchillas were behaviorally trained using operant procedures to produce pure-tone audiograms at frequencies from 63 Hz to 40 kHz. Following collection of baseline thresholds, the apical and middle turns of the experimental ear were visualized through a hole drilled in the bulla and a copper cryoprobe that had been cooled in liquid nitrogen was placed on the apical turn of the cochlea. Post-lesion threshold shifts from two subjects showed a flat loss of approximately 20 dB restricted to frequencies below either 710 Hz or 1 kHz; thresholds were normal at higher frequencies. The cytocochleograms, prepared from the ears following completion of threshold testing, show an almost complete loss of both inner and outer hair cells in the apical-most 20% of the cochlea with an abrupt transition region to areas of normal-looking hair cell populations. The relationship between the frequencies at which hearing was impaired and the location of missing hair cells along the basilar membrane is in agreement with the frequency-place map for the chinchilla of Eldredge et al. [(1981) J. Acoust. Soc. Am. 69, 1091-1095]. The magnitude of the loss, however, is less than might be expected based on comparison with threshold shifts produced by similar pathology in the basal turns.

Acoustic Stimulation↗