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Results for “Auditory Threshold”

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At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

Experiences with the cochlear implant in preschool children.

Years of experience with the cochlear implant in profoundly deaf adults led to a decision to attempt to extend the benefits of this device to children. As of March 15, 1983, 43 deaf children ranging in age from 2.7 to 17.5 years have been implanted. Seventeen of these are children under 6 years of age. All had worn hearing aids but demonstrated little or no benefit from them. Auditory thresholds with the implant are significantly better than those obtained unaided and with hearing aids. Although a longer period of experience is required, the preschool-aged children can eventually make the same auditory discriminations as older children and adults. Long-term impact on speech and language development remains to be determined, but there is already evidence for significant improvement in these areas.

Adolescent↗
PubMed1976

Human cochlear changes in noise induced hearing loss.

The temporal bone histopathological findings in 14 ears with noise induced hearing loss are presented. The morphological changes consist mainly of hair cell loss, which is more severe in the 9 mm to 13 mm region of the cochlear duct. Within the area of maximum hair cell loss, there is a greater loss of outer hair cells than of inner hair cells. There is a good correlation between the permanent auditory threshold shifts and the spatial location of the sensory lesion according to the anatomical frequency scale.

Auditory Threshold↗
PubMed1990

The incidence of aminoglycoside antibiotic-induced hearing loss.

The definition of ototoxicity in most clinical studies of aminoglycoside antibiotics is an increase in pure-tone threshold from a baseline audiogram greater than or equal to 15 dB at two or more frequencies, or greater than or equal to 20 dB at one or more frequencies. In this study, test-retest auditory threshold differences of this magnitude were found in a group of 20 normal volunteers who were not taking any known ototoxic drugs. Depending on which of the two criteria for ototoxicity are used, these data represent a 20% or 33% incidence of ototoxicity. We believe that many of the audiometric changes reported to represent aminoglycoside antibiotic ototoxicity may actually represent the normal test-retest variability of pure-tone audiometry. If this is true, the reported incidence of hearing loss due to aminoglycoside antibiotics may be exaggerated.

Adult↗
PubMed1989

High-frequency monitoring using an electrostimulation audiometer.

Electrostimulation audiometry can provide high-frequency bone-conduction threshold measurements. To evaluate the use of such an audiometer in monitoring hearing, the following areas were investigated. (1) The variability and repeatability of threshold measurements. (2) To see if the instrument could be used on the ward where the patient would have to wear ear plugs to attenuate background noise, the effect of occluding the ears was assessed. (3) The applicability of the instrument to the range of patients in whom monitoring would be appropriate, specifically the relationship between the patient's age and the effective upper frequency limit of the audiometer. The data showed a variability in threshold measurement that is quite comparable with that obtained with conventional audiometry but which became smaller at frequencies of 12 kHz and higher. There was no overall effect on the threshold of occluding the ears, which meant that the instrument can be used to monitor a non-isolated environment such as a ward. The effective cut-off frequency was about 9 kHz for patients aged 55 years, and so the use of an electrostimulation audiometer to monitor high-frequency auditory thresholds is restricted to younger patients.

Adult↗
PubMed1979

Rodent hearing: apparatus for behavioral measurements with ultrasounds.

For frequencies from 4 to 80 kHz, the acoustic reliability, behavioral reliability and overall performance of an open platform were entirely satisfactory in measurements of "absolute" auditory thresholds (using a reward operant procedure) in Rattus norvegicus. Equal satisfaction was provided by a rodent-holder in measurements of Preyer reflex thresholds over a similar frequency range in R. norvegicus, Mus musculus, Clethrionomys glareolus, Meriones unguiculatus and Sigmodon hispidus.

Animals↗
PubMed1987

[Drug therapy in sensorineural hearing loss in childhood].

40 children were treated for progressive sensorineural hearing loss with infusions of prednisolone and pentoxifylline. After this treatment pure tone audiometric findings showed improved auditory thresholds in 52.5%. The results are discussed dependent on aetiologic findings.

Adolescent↗
PubMed1985

Sensitivity to noise in a community sample: II. Measurement of psychophysiological indices.

A sample of 77 women of high and low noise sensitivity in 1977, living in areas of high and low exposure to aircraft noise, were interviewed in the community in 1980. High, intermediate and low noise sensitive women were compared, using measures of blood pressure, heart rate, skin conductance, hearing threshold, uncomfortable loudness level and magnitude estimation of six tones. These physiological measures did not clearly distinguish different noise sensitivity groups, except that highly noise sensitive women had a consistently slower heart rate. Noise sensitivity was not related to auditory threshold. In the high aircraft noise area there were significantly more skin conductance responses than in the low aircraft noise area irrespective of noise sensitivity. This may be the result of chronic exposure to high aircraft noise.

Adolescent↗
PubMed1996

The effects of moderate and low levels of acoustic overstimulation on stereocilia and their tip links in the guinea pig.

Guinea pigs were exposed to pure tones of 10 kHz at intensities between 98 and 115 dB SPL for 5-30 min, to produce varying degrees of acoustic trauma. Changes in auditory thresholds were measured electrophysiologically, and the animals were immediately fixed for scanning electron microscopy. Correlation between morphological changes to the hair bundle and losses in threshold, showed that with the smallest degrees of trauma (98 dB SPL for 15 min, mean maximum threshold loss of 22 dB), damage was confined to a small stretch of inner hair cells (IHC), with only subtle changes to the stereocilia of the outer hair cells (OHC). At exposure intensities greater than 102 dB SPL (duration: 15 min) the IHC stereocilia in the centre of the lesion were always substantially disarrayed. Substantial damage to the OHC bundles was seen only with exposures above 110 dB SPL (duration: > or = 5 min), producing threshold losses of 50 dB or more. Tip links were lost only where the stereocilia were disarrayed. It is concluded that the tip links are not the most vulnerable components of the cochlear hair cell, but that relatively low levels of acoustic stimulation can cause significant damage to the stereociliary bundle of the IHCs.

Acoustic Stimulation↗
PubMed2004

Hearing thresholds in patients affected by rheumatoid arthritis.

The aim of the study was to evaluate hearing thresholds in 38 patients with rheumatoid arthritis, divided according to disease activity into active (group A, n = 20) and non-active (group B, n = 18) patients. Pure tone audiometry, tympanometry and complete rheumatological assessment were performed. All patients presented poorer auditory thresholds compared with controls. Patients of group A had both air and bone conduction thresholds poorer than group B (although not statistically significant), and most patients of both groups presented an air-bone (a-b) gap. No significant difference in middle ear pressure was noticed between patients and controls. No correlation between hearing impairment and duration of the disease or patients' age was found. The high prevalence of hearing loss in autoimmune diseases supports the importance of audiometric evaluation in such patients. The auditory recovery through middle ear surgery before cranial nerve involvement could be considered in selected patients. Further investigations are needed for a better knowledge of the middle and inner ear involvement in patients with rheumatoid arthritis.

Acoustic Impedance Tests↗
PubMed1991

Aging and consonant errors in reverberation and noise.

Identification accuracy and error patterns on the City University of New York (CUNY) Nonsense Syllable Test were examined for three groups of subjects (young normal-hearing, older hearing-impaired, and older with minimal hearing loss) listening binaurally in four conditions (quiet, noise, reverberation, and reverberation plus noise). Percent-correct performance was analyzed for stimuli aggregated by place and manner categories, and error patterns were examined via analysis of variance and correlational procedures. Results suggested that some of the difficulty experienced by the older subjects was related to amount of hearing loss, but a portion of the data could not be explained by elevated auditory thresholds. Confusion patterns also varied across listening conditions, especially for the nasal and semivowel stimuli.

Adult↗
PubMedDate not supplied

Control by the evoked potential of the brain stem of the administration of dibekacine in premature infants.

The administration of dibekacine to 10 newborn carriers of a germ infection--or staphylococcus, was controlled for auditory tolerance. The auditory threshold was controlled by the evoked potential of the brain stem. Medication never caused the threshold to change. The evolution of latency in waves J1, J3 and J5 could not be seen except in wave 1 where latency decreased, as can be seen in other premature infants of babies born at term.

Auditory Threshold↗
PubMedDate not supplied

[Brain stem potentials evoked by "click" (author's transl)].

The authors describe the results of click at a recurrence frequency of 10 C/S in evoked responses of the brain stem, firstly in twenty normal individuals, with headphones or in a free area, making it possible to define a range of physiological responses to the different intensities, then in seventeen pathological individuals consisting of six cases of conduction deafness and eleven of perceptive deafness. On the basis of this study, they attempt to demonstrate the value of this type of examination not only in the determination of objective auditory threshold, but also in that of the type of deafness: conductive or perceptive. The method even makes it possible to approximately define the general appearance of the frequency distribution at the threshold according to the slope of the different latencies of P5. In the opinion of the authors, the chief advantages are the decrease in the time required for the test and the possibility of its use in the study of prosthetic gain.

Adolescent↗
PubMed1995

Four weeks inhalation exposure to n-heptane causes loss of auditory sensitivity in rats.

The effects of exposure to 800 or 4000 p.p.m. of n-heptane, CAS No. [142-82-5]) 6 hr per day during a period of 28 days, on the function of the auditory system were examined by measurements of auditory brain stem response (ABR) in Long Evans rats. The ABR was measured simultaneously with both needle electrodes and implanted electrodes. The wave forms recorded with the two types of electrodes were similar, but the amplitudes were largest on the recordings with implanted electrodes. The overall ratio between the amplitudes obtained with implanted electrodes and with needle electrodes was 1.4 for peak Ia and 2.5 for peak IV of the ABR. The exposure to n-heptane (4000 p.p.m.) reduced the amplitudes of components Ia and IV of the ABR. The reduction was most consistent for component IV and most pronounced at higher frequencies and intensities. The reduction in ABR corresponds to an increase in the auditory threshold of approximately 10 dB at all frequencies. Neither the latencies nor the interpeak latencies of components Ia and IV were changed. No significant changes in ABR were observed in the group exposed to 800 p.p.m. The mechanism behind the ototoxicity of organic solvents is discussed.

Administration, Inhalation↗
PubMed1995

Automatic detection of auditory brainstem responses using feature vectors.

The efficiency of several methods for the automatic detection of near threshold auditory brainstem responses (ABRs), based on feature vectors, was assessed on a sample of 374 recordings obtained from neonates. Features are quantitative descriptors of different aspects of the response commonly taken into consideration by expert ABR judges, such as: similarity with a template, reliability of the response, and intrinsic morphological characteristics. The classification methods used were: comparisons of individual features with a threshold, linear discriminant functions based on combination of features, artificial neural networks (ANNs) based on the raw ABR, and ANNs based on combinations of features. The network used was a modified version of the Fuzzy ART Map model. The accuracy of the classification into normal and abnormal (as previously scored by a panel of experts) was assessed with methods from signal detection theory. Our results showed that the approaches based on feature vectors (discriminant function and ANN) performed more efficiently than the ANN with raw data, or the individual features.

Algorithms↗
PubMedDate not supplied

[The effect of perinatal factors on development of congenital sensorineural hearing loss in children].

Combined treatment with hyperbaric oxygenation (HBO), antihypoxants, correctors of microcirculatory, liquor-dynamic and metabolic disorders in the internal ear was used in 99 children aged 1 month to 2.5 years with perinatal neurosensory hypoacusis. A 10-15 dB decrease in auditory thresholds was achieved in 10% of the patients. HBO application in combined treatment of the above patients was pathogenetically validated.

Adolescent↗
PubMed1988

Action potential threshold elevation in the guinea-pig as a function of impact noise exposure energy.

Eighteen groups of guinea pigs were exposed to a simulated impact noise for periods of 1.5-24 h. The peak level was kept constant at 131.5 dB and the repetition rate was varied to give seven different equivalent levels (Leq) between 96 and 117 dB. The auditory thresholds were assessed by electrocochleography after 1 month and compared with those of a control group. Significant damage occurred even at the lowest exposure energy used. When the total exposure energy was expressed on a decibel scale, the threshold elevation (1-10 kHz) increased 1.07 dB for each decibel increase in the exposure energy, regardless of the combination of Leq and exposure time. The results of the study thus support the equal-energy hypothesis under these conditions.

Animals↗
PubMed1992

Carboplatin and cisplatin ototoxicity in guinea pigs.

Ototoxic effects of cisplatin (1.5 mg/kg), cisplatin with mannitol (1.5 mg/kg cisplatin with 15 mg/kg mannitol) and carboplatin (6 mg/kg) were compared in guinea pigs treated 5 days a week for 5 consecutive weeks. Auditory thresholds were measured in awake animals by means of the compound action potential recorded from electrodes implanted near the round window. The endocochlear potential (EP) was measured in the first turn through the round window, and hair cell counts were estimated by the surface specimen technique. The most pronounced ototoxicity (threshold shifts and hair cell loss) was observed with pure cisplatin. Cisplatin with mannitol appeared to be less toxic than pure cisplatin, and carboplatin the least toxic. Even carboplatin produced significant threshold shifts, particularly at high frequencies, but they were not accompanied by hair cell loss. Values of EP were not different from those in normal control animals.

Acoustic Stimulation↗