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Results for “Auditory Threshold”

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At least 271 records · Page 15Linked to original sources

PubMed1980

Temporary auditory threshold shift following sophomore operative technique laboratory.

Twenty sophomore dental students were studied for the "temporary threshold shift" (TTS) due to exposure to the noise of high-speed dental headpieces during technique laboratory sessions. TTS was experienced at all four frequencies tested--8000, 6000, 4000, and 3000 hertz, but tended to be greater and of longer duration at the higher frequencies. Approximately one-fourth of the students still had some hearing loss 15 minutes after leaving the laboratory.

Auditory Threshold↗

PubMed1989

[Comparison of auditory threshold and loudness in the Bing test].

The threshold and loudness comparison techniques of the Bing test were performed in a quantitative manner in both ears of 14 subjects. The results were related to their air-bone gap at 500 Hz. The study showed that the air-bone gap influenced a positive occlusion effect, but did not influence its subsequent magnitude. The magnitudes of the results of the occlusion test performed in these two ways were significantly related to each other.

Adult↗

PubMed1984

[Permanent shift of auditory thresholds caused by continuous and impulse noise: comparative studies].

The studies included two groups of workers, only men, of maximally similar structure of age and length of employment but different exposure conditions. 112 cotton weavers worked under continuous noise and 64 forgers under impulse noise. Noise measurements demonstrated that in both groups the equivalent levels were almost identical (101.8 dB-A in the weaving room and 100.4 dB-A at the forge). The permanent hearing threshold shift in both types of exposure was found to exhibit similar time course, developing within 10-15 years of exposure, then stabilizing, and reaching the asymptote within about 20 years. Despite the same dose of acoustic energy, the hearing impairment induced by impulse noise was greater and is characterized by the maximum loss at 6 kHz frequency, as opposed to the notch at 4 kHz typical of continuous noise.

Adult↗

PubMed2002

The acute effects of tetrahydrocannabinol on auditory threshold and frequency resolution in human subjects.

AIMS: The study was designed to investigate the acute effects of ingested tetrahydrocannabinol (THC) on auditory function. METHODS: Eight male subjects (aged 22-30 years), who had previous experience of cannabis use, took part in this study. They performed air conduction pure tone audiometry in both ears over 0.5-8 kHz. A simple test of frequency selectivity by detecting a 4-kHz tone under two masking noise conditions was also carried out in one ear. Three test sessions at weekly intervals were carried out, at the start of which they ingested a capsule containing either placebo, or 7.5 or 15 mg of THC. These were administered in a randomized cross-over, double-blind manner. Auditory testing as described above was carried out 2 hours after ingestion. Blood samples were also obtained at this time point and assayed for delta 9- and 11-OH-THC levels. RESULTS: No significant changes in threshold or frequency resolution were seen with the dosages employed in this study. CONCLUSIONS: This suggests that THC at the plasma levels attained in this study does not have profound effect on the processing of elementary stimuli by the auditory pathway.

Administration, Oral↗

PubMedDate not supplied

[Correlation between auditory threshold and transitory evoked otoacoustic emissions].

The aim of this study was to compare transiently evoked otoacoustic emissions (TEOAE) and pure tone audiometry in normal hearing ears and ears with cochlear hearing loss (60 ears of 30 subjects), to obtain defined data on qualitative and quantitative correlations. We wanted to determine the reliability with which a clinical examiner could predict a typical, idealized audiometric configuration from TEOAE measurements. The results show that the presence of otoacoustic emissions drops as a function of hearing loss and that there is a highly statistically significant correlation between characteristics of otoacoustic emission (coefficient of correlation and strength of otoacoustic emissions) and hearing loss at 1000-3000 Hz frequency. Otoacoustic emissions are never found when hearing loss at 1000-3000 Hz exceeds 36 dBnHL. The main practical conclusion is that otoacoustic emission presence indicates middle frequency functional integrity of the outer hair cells of Corti's organ. Absence of otoacoustic emissions is harder to interpret and requires further audiological diagnosis (brain-stem auditory evoked potentials).

Acoustic Stimulation↗

PubMed1976

Hypoxia and auditory thresholds.

This paper reports the effects of hypoxia on hearing. Pure tone hearing and speech discrimination were tested at ground level and during hypoxic states at simulated altitudes of 4,600 m (15,000 ft) and 6,100 m (20,000 ft) in a high-altitude chamber. Pure tone hearing was not significantly altered during hypoxia produced by this method. Speech discrimination showed alterations, possibly due to central nervous system hypoxia. It was concluded that hypoxia does not cause significant deterioration of hearing for pure tones.

Adult↗

PubMed1988

Dietary restriction and presbyacusis: periods of restriction and auditory threshold losses in the CBA/J mouse.

Dietary restriction was imposed on CBA/J mice, animals which develop presbyacusis late in their lives. Animals restricted for their whole lives, as well as those restricted after midlife, had less presbyacusis than did control mice fed ad libitum. Dietary restriction did not increase the life spans of these mice. Restriction until midlife did not protect from presbyacusis, nor did it increase life span. In this genotype, dietary restriction protects against hearing loss only if it occurs at the age of most rapid decline of cochlear function.

Aging↗

PubMed1975

[Development of auditory threshold in the 1st weeks after stapes surgery. Study of 50 cases].

We have treated 50 cases of otosclerosis by transplatinary piston. We made a statistical study of the recuperation modalities concerning frequency and time. The highest hearing gain was obtained each time between 250 cps and 500 cps. The maximum hearing recuperation occurs usually, three weeks after the intervention for the lower and mid-frequencies, two months for the higher frequencies. Finally we have noticed that the intervention was helpful as well for the opposite ear as for the operated one.

Acoustic Stimulation↗

PubMed1982

[Auditory threshold and the degree of its temporary and permanent shifts in the textile industry workers].

Hearing threshold was measured with digital audiometer CASK-431 in transportable soundproof booth GIG-AU-1 in 170 women and 75 men before and at the end of the afternoon shift work in the weaving-mill with shuttle looms, where an average noise level was 100 dB(A). The average hearing losses calculated from the formula dB (1000 Hz + 2000 Hz + 4000 Hz): 3 were higher than those calculated from the formula db (500 Hz + 1000 Hz + 2000 Hz): 3. There was also a higher correlation coefficient between the occupational exposure to noise and the values of hearing loss calculated according to the former of the mentioned formulae, as compared to the latter. Workers wearing individual hearing protectors from the glass microfibres suffered from temporary threshold shift (TTS) of few dB whereas in those wearing no hearing protectors the TTS attained 10 to 24 dB on average. Among the women--workers of comparable age and occupational exposure to noise the hearing losses were higher in those living in noisy communities than in those living in quiet communities. This result is indicative of cumulative effects of community and industrial noise in respect to the hearing damage. Regulations for permissible noise levels in occupational environment should involve the kind of exposure to the community noise.

Adolescent↗

PubMed1982

Lack of effect of contralateral speech discourse on auditory threshold response behavior.

Three pilot experiments were conducted with normal-hearing adults on the effects of contralateral speech discourse on monaural intensive threshold at 1 kc/s. Two voices simultaneously reading dissimilar passages were presented to the non-test ear. Pure tones and speech were led to insert receivers. Threshold assessment was by operant techniques with feedback for correct response. Stimulus presentation and response recording and retrieval were under computer control. Performance was analyzed by threshold central tendencies and variances, by slopes of performance-level curves, and by slopes of curves for response-decision latencies vs level. In Exper. I (N:5), Ss made threshold judgments while in the contralateral ear speech was presented at 30 db SL, in 2-sec samples with 2-25- sec silent intervals intervening. In Exper. II (N:3), the interrupted speech was at levels of -10, 10, 50, and 70 db; in addition, 4 blocks of thresholds were taken at 30 db SL to examine adaptation effects, if any. In Exper. III (N:3), speech was continuous at the levels of 10, 30, 50, and 70 db. None of the characteristics of the speech appeared to affect performance by any of the 3 indices at any level, for any S systematically. It was concluded that inter- and intra-subject variability may be the key to much of the conflicting results in the literature in the area of performance in noise.

Adaptation, Physiological↗

PubMed1999

TEOAE-based estimation of the auditory threshold in the mid-octave frequencies.

The purpose of this study was to estimate the hearing levels, at the mid-frequencies, of 233 ears with sensorineural hearing loss by classifying the corresponding transiently evoked otoacoustic emissions (TEOAE) recordings into three threshold groups. A classification algorithm was based upon a discriminant analysis of fast Fourier transform (FFT) data, evoked by non-linear click stimuli of 80 (+/-2) dB SPL per ear. To validate the efficiency of the proposed methodology TEOAE recordings were initially grouped by mean hearing level values of the 1 kHz and 2 kHz octaves into three threshold ranges according to two strategy schemes: in the first, TEOAE data were assigned into 10-19 dB HL, 20-39 dB HL or > or = 40 dB HL groups. In the second, TEOAE data were assigned into 10-29 > dB H >, 30-39 dB HL or > or = 40 dB HL groups. The most accurate prediction estimates were obtained from the second strategy scheme with a 90.9% accuracy in the 10-29 dB HL group, 82% in the 30-39 dB HL group and 71.4% in the > or = 40 dB HL group.

Adult↗

PubMedDate not supplied

[Auditory thresholds in young Italians from 18-19 years of age].

The aim of the study was to assess the state of hearing levels in young Italian subjects via an epidemiological study, and also, by means of a questionnaire, to assess the attitude of young people to music, how they listen to music and how they perceive the risk of noise-induced hearing damage. The sample studied consisted of 391 youths undergoing their first medical examination for military service. The hearing threshold was assessed by means of a semiclinical tonal audiometry with sound-proof earphones calibrated to ISO Standard 389 following the method of ISO Standard 6189. At the end of the study 315 youths were judged eligible for the study, 81% of whom lived in the city of Milan. 63% said they went to a discotheque 1-4 times a week and 3% said they listened to music with earphones at maximum volume. These conditions are considered to be potentially dangerous for hearing since among youths leaving discotheques disorders have been observed that are indicative of hearing fatigue: lowering of the hearing level 7%, buzzing in the ears 37%, sense of muffled sound 12%. In the group studied, environmental noise was a factor of disturbance for sleep (13%), for study and reading (43%), listening to the radio, to music and watching TV (29%). Only 7 youths said their hearing was "not normal", but the thresholds were all higher than audiometric zero, which are clearly worse than the values observed in similar studies reported in the literature. This study reports the mean values, SD, minimum and maximum and centile values of the distribution of hearing thresholds, separately for right and left ears. A comparison was made between the hearing in the group least exposed: a significant difference was observed only for the right ear while for the left ear there was only a tendency. The authors conclude that hearing in young people to-day is worse than in the past, whatever be the causes, and that due account should be taken of this state of affairs, by encouraging prevention programmes for noise-induce hearing loss at all levels and on every possible occasion.

Adolescent↗

PubMed1995

[Changes in the auditory threshold for air and bone conduction in relation to middle ear pressure in probands with normal hearing].

Under pressure in the tympanic cavity causes increased impedance of the middle ear. Gellé was the first to describe increased bone conduction levels following alteration of ear canal pressure in healthy ears. Up to now, no investigation which quantitatively describes the elevation of the hearing threshold induced by various levels of under pressure in the middle ear has been published. In a pressure chamber, we induced relative under pressure in the middle ears of 15 adults with normal hearing. We measured hearing thresholds and calculated medium values at four separate levels of under pressure. At an under pressure of 3.3 kPa, air conduction was reduced by a few dB at 500 and 1000 Hz. Alterations of bone conduction were first seen at 6.6 kPa accompanied by increased deterioration of air conduction. Both effects became more obvious at 10 kPa; and at a maximum under pressure of 13.3 kPa, a deterioration of air conduction by more than 25 dB was seen at 250, 500, and 1000 Hz. Bone conduction deteriorated by more than 10 dB at 500 and 1000 Hz. There was no uniformity in the development of bone conduction threshold in the condition of under pressure: Several ears expressed only slight changes, but in some ears we saw an increase of bone conduction at the same rate as air conduction. Minor alterations were observed in frequencies above 1000 Hz. These results may be only partially explained by middle ear effects like the reduction of the ostio-tympanic component of bone conduction caused by increased stiffness of the ossicles. We believe that disturbances of inner ear mechanics play a role in the deterioration of bone conduction levels, too.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Impedance Tests↗

PubMed1989

Auditory thresholds in the American cockroach (Orthoptera: Blattidae): estimates using single-unit and compound-action potential recordings.

Recent commercial suggestions that insect populations can be controlled through the use of ultrasound raises the question of whether or not certain insects have receptors that are sensitive to high-frequency sound. Single neural unit discharges and compound-action potentials were recorded from the ventral nerve cord in the American cockroach, Periplaneta americana L., to constant rise time tone pulses from 100 to 40,000 hertz (Hz). Unit responses and compound-action potentials show that the cockroach is insensitive to sound above approximately 3,000 Hz. Data relating latency of the response to intensity of the stimulus suggest that the cockroach cercal system operates on the principle of energy envelope detection. Decreases in latency likely occur primarily as a result of increases in the rate of membrane depolarization in cercal dendrites.

Action Potentials↗

PubMed1986

[A permanent noise-induced shift in the auditory threshold in textile industry workers].

Hearing thresholds have been measured in 236 cotton weaving mill workers (124 women: average age 42.5 +/- 11.2 years, average length of employment 19.5 +/- 10.6 years and 112 men: average age 41.2 +/- 10.3 years, average length of employment 19.0 +/- 11.1 years) exposed to continuous broadband noise of the constant level of approx. 100 dB-A. 90% of subjects exhibited the permanent threshold shift characterized by a great individual variability and maximum loss at the 4 kHz frequency. Those lesions were getting enhanced with increasing length of exposure and were more serious in elder age groups. No significant differences between the hearing loss intensity in men and women were found. The development of the hearing loss is characterized by its rapid increase within 3, 4 and 6 kHz during the initial 8 years of exposure, stabilization between years 9-12 and slow moderate increase within the further 13-31 years of exposure. Those conclusions should be implemented into practice through an increase in the frequency of preventive audiometric tests in the initial period of work in exposure which has such a great impact on the development of the hearing impairment.

Adult↗

PubMed1991

[Effect of noise, exertion and thermal load on temporary auditory threshold shift (TTS) and on fatigue].

Temporary threshold shifts were determined in 14 voluntary subjects who were exposed during one hour to noise levels 70, 85 and 100 dB(A) accompanied by physical exercise (30% VO2max), thermal load (TE = 32.0 +/- 0.8 degrees C), and after combined exposure to these three factors. Before and after each exposure, temporary were measured threshold shifts (TTS2) at frequencies 3, 4 and 6 kHz. The psychophysical fatigue was determined using flicker and blinking tests. The results showed that exposure to noise, noise and thermal load, noise and exercise, and combined noise-exercise -thermal load exposure induced statistically significant increases of TTS values, especially at 85 and 100 dB(A) noise levels. Noise and thermal load, noise and exercise, and the combination of the three did not cause psychophysical fatigue, probably on account of the short duration of exposure. The results of this work show that estimation of exposure to noise, performed by measuring noise levels at workplaces and comparing them with the current standards without considering the effects of exercise and/or thermal load is not sufficient to evaluate occupational exposure and the risk of permanent hearing loss.

Adult↗

PubMed1990

Auditory brainstem response results as predictors of behavioral auditory thresholds in severe and profound hearing impairment.

Pediatric cochlear implantation is restricted to patients with stable, bilateral profound sensorineural hearing losses who derive no benefit from conventional amplification. Obtaining reliable audiologic thresholds in a young child with sudden or early-onset hearing loss can be challenging. This study examines the accuracy with which auditory brainstem response evaluation can predict unaided and aided behavioral thresholds in a child with severe-to-profound hearing loss. Reliable behavioral thresholds were obtained on 119 children who had no measurable click-evoked auditory brainstem responses at instrumentation limits of 100 dB HLn. These data show that an absent auditory brainstem response at 100 dB HLn does not necessarily indicate the absence of measurable unaided hearing for test frequencies ranging from 250 Hz to 4000 Hz. Average aided thresholds of better than 60 dB were present in 43% of the children for 500, 1000, and 2000 Hz and in 53% for 500 and 1000 Hz. Therefore, the absence of a click-evoked auditory brainstem response at 100 dB HLn in a young child is not prima facie evidence of the child's cochlear implant candidacy.

Audiometry, Evoked Response↗

PubMed2006

Residual inhibition functions in relation to tinnitus spectra and auditory threshold shift.

CONCLUSIONS: Psychoacoustic functions relating the depth and duration of tinnitus suppression ('residual inhibition') to the center frequency of band-passed noise masking sounds appear to span the region of hearing loss, as do psychoacoustic measurements of the tinnitus spectrum. The results (1) suggest that cortical map reorganization induced by hearing loss is not the principal source of the tinnitus sensation and (2) provide a necessary baseline for optimizing residual inhibition in individual cases. OBJECTIVE: To measure residual inhibition functions and tinnitus spectra using sounds spanning the region of hearing loss. MATERIALS AND METHODS: Three subject-driven, computer-based tools were developed and applied to measure psychoacoustic properties of tinnitus and residual inhibition in 32 subjects with chronic tonal, ringing, or hissing tinnitus. Residual inhibition functions were measured with band-passed noise sounds varying in center frequency up to 12.0 kHz. RESULTS: The depth and duration of residual inhibition increased with the center frequency of the band-passed noise stimuli. Near-elimination of tinnitus for up to 45 s was reported by 8/24 (33%) subjects at center frequencies above 3 kHz (these cases distributed across tinnitus types). Tinnitus spectra covered the region of hearing loss with no preponderance of frequencies near the audiometric edge of normal hearing.

Adult↗