PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Auditory Threshold”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMed1975

The role of the middle ear in acoustic trauma from impulses.

Exposure to high intensity impulse noise may produce a wide range of audiometric and histological effects in experimental animals. The objective of this study was to assess the changes in the middle ear mechanism after impulse noise exposure and to relate these changes to the audiometric and histological effects. Nine monaural chinchilla were exposed to either 161 or 166 db peak SPL impulses of 1 msec "A" duration, presented at a rate of 1 per minute for 50 minutes. The conductive mechanism of the chinchilla was assessed using standard clinical measures of static and dynamic impedance before and after the noise exposure. Auditory thresholds were measured before and after noise exposure using the average evoked response (AER) technique. At 30 days post-exposure, the animals were sacrificed for histology. Pre-exposure tympanometry showed that: 1. the total mean impedance of the chinchilla ear is considerably lower than that of man; 2. a method related hysterisis effect is present in both the susceptance and conductance tympanograms; and 3. sedation has a significant effect on the total impedance of the ear and on the shape of the tympanograms. After exposure to high level impulse noise: 1. tympanograms become irregular and double peaked, indicating tympanic membrane stress; 2. for the given exposure, 166 db is the impulse intensity needed to rupture consistently the tympanic membrane; and 3. audiometric and histological data correlate with the tympanometric findings and demonstrate a protective effect of a tympanic membrane rupture on the cochlea.

Animals↗
PubMed1988

Open-set word recognition with the Duren/Cologne extracochlear implant.

The author visited Duren, West Germany and evaluated the performance of five patients implanted with the extracochlear Duren/Cologne implant who achieved better word recognition levels. Word and sentence speech reception tests were presented live-voice by a familiar German speaker. Performance ranged from 1% to 80% correct word recognition with sentence material, 0% to 63% correct word recognition with word lists, and 13% to 86% correct recognition for phonemes in words. One patient achieved high-level, open-set word recognition without visual cues, using single-channel, extracochlear stimulation. Preimplant auditory thresholds in her implanted ear were 60, 65, 90, and 105 dB HL at octave frequencies from 125 to 1,000 Hz, respectively. There was no measurable hearing at higher audiometric frequencies.

Adult↗
PubMed2000

Visual speechreading and cognitive performance in hearing-impaired and normal hearing children (11-14 years).

BACKGROUND: Previous research has demonstrated that parts of the variation in adults' speechreading performance can be explained by the characteristics of some cognitive components. However, these results apply to populations of adults and less is known as to how results for populations of adults can be generalised to populations of children. AIM: This study aimed to examine cognitive and visual skills in a group of bilaterally, moderately hearing-impaired children and a group of normal hearing children and how these two skills relate to variability in speechreading of context-embedded sentences. SAMPLE: Twenty-three hearing-impaired children (mean age: 12.7) and 23 normal hearing children (mean age: 12.5) matched for age, sex, verbal ability and school grades. The mean 'better ear' auditory threshold for the hearing-impaired was 44.8 dB. RESULTS: The hearing-impaired children outperformed the normal hearing children on a sentence-based speechreading task and on a visual-visual word-decoding task, but not on a word-discrimination task. Differing from the case of adults, most cognitive tasks proved to be significantly related to sentence-based speechreading performance, where working memory capacity and visual word-decoding skill proved to be the strongest predictors. CONCLUSIONS: Speechreading is more cognitively demanding for children than for adults as they have not developed their cognitive abilities to the same extent as adults. Thus, they have to devote more processing capacity, relative to their total cognitive processing capacity, to the speechreading task. Skilled visual word-decoding and cognitive skills, together with everyday exposure to situations where speechreading is required, are some of the candidates for explanation of the hearing-impaired children's superior speechreading skill.

Adolescent↗
PubMedDate not supplied

A scanning electron microscopic study of cochlear changes in iron-deficient rats.

The effects of iron deficiency on the cochlea were studied in growing rats fed with a basic iron-deficient diet for 80 days. The electrophysiological changes (auditory thresholds raised more than 15 dB) were observed in 47% of the cochleas of iron-deficient rats. When these organs of Corti were examined by scanning electron microscopy, abnormalities of outer or inner hair cells were found, as follows: (1) fusion and torsion of the stereocilia, (2) coalescence of adjacent stereocilia in the same row, (3) loss of sensory hair stiffness, and (4) loss of stereocilia. Within each lesion, the neighbouring supporting cells and their microvilli showed no damage. The findings indicate that cochlear impairment can be induced by iron deficiency. The peroxidative mechanisms responsible for the lesions of stereocilia in iron deficiency are discussed.

Anemia, Hypochromic↗
PubMedDate not supplied

Tonotopic organization of human auditory cortex analyzed by SPET.

Single photon emission tomography (SPET) was used to map blood flow increases in the temporal and parietal cortex of 16 normally-hearing subjects after auditory stimulation. Eight subjects were stimulated with a multifrequency 40 dB HL pure tone at 250, 500, 1000, 2000, 4000 Hz, each frequency varying every 30 s. Single 500 Hz pure tones at 40 dB HL were delivered to the remainder of the subjects. Five bilaterally deaf subjects were used as controls. Marked cerebral flow increase following acoustic stimulation with a significantly prevalent activation of the contralateral temporal cortex was achieved (p < 0.001). According to the tonotopic organization of the human auditory cortex, low monofrequency stimulation activated the most lateral sagittal tomograms (from 48.75 to 56.25 mm laterally to the brain midline) only, while multifrequency stimuli activated all sagittal tomograms (from 18.75 to 56.25 mm). On the basis of these results, it is likely that SPET is able to give real information on the cortical distribution of the auditory frequency range, taking into account the number and position of the activated slices. Further clinical investigations in order to define the relationships among blood flow cortical increases, stimulus intensity and auditory threshold, are in progress.

Adult↗
PubMed1992

A comparison of netilmicin and tobramycin therapy in patients with renal impairment.

We evaluated the toxicity and efficacy of netilmicin and tobramycin in 89 older adults with serious bacterial infections and pre-existing renal impairment in a prospective, blinded, randomized trial. Complete resolution or improvement of infection occurred at 34/36 (94%) evaluable sites in netilmicin-treated patients and at 26/31 (84%) evaluable sites in tobramycin-treated patients. 10/44 (23%) netilmicin- and 7/45 (16%) tobramycin-treated patients experienced nephrotoxicity during treatment. The mean serum creatinine level improved significantly at the end of therapy compared to pre-treatment in those patients who did not experience nephrotoxicity in both treatment groups. 5/19 (26%) netilmicin-treated patients and 2/18 (11%) tobramycin-treated patients assessable for ototoxicity experienced decrements in auditory thresholds. Ototoxic netilmicin-treated patients had higher serum netilmicin levels than did non-ototoxic patients. Patients who experienced ototoxicity were not more likely to have experienced nephrotoxicity. The rates of toxicity were not statistically different and were similar to those seen in studies of patients with normal pre-treatment renal function.

Aged↗
PubMed1992

Non-organic hearing loss in young persons: transient episode or indicator of deep-seated difficulty.

Depressed auditory thresholds without evidence of organic hearing loss are observed in a small percentage of children and young adults. Several studies suggest that non-organic hearing loss (NOHL) is a manifestation of, or reaction to stress. Proposed treatments range from ignoring the apparent hearing loss through the use of psychotherapy and/or counselling to confronting the individual with evidence to prove that there is no real loss of function. Few studies report on long-term outcome. Thirty-eight subjects who had been diagnosed more than six and up to twenty-seven years ago as having NOHL were identified from records. Efforts were made to determine if there was any evidence of longer term effects. Nine were untraceable. Of those reviewed one was established as a malingerer; five had concurrent speech problems; one was possibly dyslexic; five were or had been under psychiatric care. These findings suggest that NOHL may, in some individuals, indicate underlying problems that merit detailed investigation and treatment.

Adolescent↗
PubMed1999

[Experimental studies of the protective effect of ginkgo biloba extract (GBE) on cisplatin-induced toxicity in rats].

Cisplatin (CDDP) is an effective antineoplastic agent in the treatment of solid malignant tumors. Its clinical use, however, is limited because of various side effects including sensorineural hearing loss. Several agents have been proposed to reduce these side effects. GBE has recently been reported to scavenge superoxide and hydroxyl radicals, resulting in a reduction of lipid peroxidation. GBE is expected to protect against CDDP-induced toxicity because its generative mechanism is thought to be associated with free-radical formation. The purpose of the present study was to evaluate GBE's efficacy as a protective agent against cisplatin-induced ototoxicity. Fisher rats were used in this study and were divided into three treatment groups: 1) animals administered 1.0 mg of CDDP per kg for 10 days (Group I), 2) animals receiving 100 mg of GBE per kg 90 min before administration 1.0 mg of CDDP per kg (Group II) and 3) a vehicle control (Group III). First, the protective effect of GBE on CDDP-induced ototoxicity was investigated. The auditory threshold was evaluated by means of the compound action potential (CAP) recording. After CAP recordings, cochlear sensory epithelia were observed throughout the cochlea by scanning electron microscopy. In Group II, the elevation of CAP thresholds at 12 kHz, 16 kHz, 20 kHz and the missing rate for the outer hair cells were significantly reduced as compared to those in Group I. These data suggest that GBE is effective for otoprotection against CDDP. Second, the protective effect of GBE on CDDP-induced nephrotoxicity was evaluated. Nephrotoxicity was evaluated by means of measurement of serum BUN and creatinine and histopathological examination of the kidney. These were significant differences in serum BUN and creatinine levels between Group I and Group II. Third, the influence of GBE against the antitumor effect of CDDP was researched in the rats inoculated subcutaneously with SCC-158 squamous cell carcinoma cells. There was no difference in tumor growth rate (TGR) between Group I and Group II. The result suggested that the combined administration had no influence on the antitumor activity of CDDP. In conclusion, the co-administration of CDDP with GBE is beneficial to ameliorate CDDP-induced toxicity without attenuation of CDDP antitumor activity.

Animals↗
PubMed1999

Noise-induced neurologic disturbances in divers exposed to intense water-borne sound: two case reports.

Divers may be exposed to intense noise underwater. Two cases of neurologic disturbances during experimental exposures to 15 min of continuous underwater sound are described. Sound exposure in the first case consisted of a warble tone with center frequency of 240 Hz and a sound pressure level of 160 dB re 1 microPa. Symptoms during exposure consisted of somnolence, lightheadedness, and an inability to concentrate. No apparent effect on hearing was noted. In the second case, a center frequency of 1,000 Hz at 181 dB was used. Lightheadedness, inability to concentrate, agitation, and head vibrations were noted during the exposure. The diver also exhibited a temporary auditory threshold shift of 19.2 dB. In both cases, overt symptoms resolved within 30 min after exposure, but both divers reported recurrent symptoms days to weeks after the exposures. Medical histories and examinations, assessment of dive profiles, and breathing gas analysis failed to support a source other than the sound exposures to account for the symptoms observed. Potential mechanisms for the described symptoms are discussed.

Adult↗
PubMed2000

[Extended high-frequency audiometry--reproducibility of two type of earphones].

Auditory thresholds in the frequency range of 0.5-6 kHz and in the extended high-frequency range (8-16 kHz, according to ISO 389-5) were measured for one ear of 139 otologically healthy persons (77 females, 62 males, mean age 25 years, range 12-54 years) using insert earphones ER-2 of Etymotic Research and circumaural earphones HDA 200 of Sennheiser. For each subject, two measures of the thresholds were obtained for both types of transducers during the same test session. Repeatability was significantly worse in the 8-16 kHz region (repeated thresholds were within +/- 5 dB for 90% of the thresholds of each frequency and within +/- 10 dB for 98%), compared to that in the 0.5-6 kHz region (+/- 5 dB for 97%, +/- 10 dB for 100%), as determined by paired t-test and Wilcoxon signed rank test. Repeatability was similar for both transducer types.

Adolescent↗
PubMed2001

The effect of recreational gunfire noise on hearing in workers exposed to occupational noise.

Hearing sensitivity for an experimental group of 278 industrial workers who engaged in recreational shooting was compared with that of an age-matched control group of 278 nonshooting industrial workers to examine the effect of gunfire exposure on auditory thresholds. The influence of age and the number of unprotected gunshot exposures per year also was examined. The subjects in the experimental group completed a questionnaire to define the types of firearms used, the number of years shooting, and the number of protected and unprotected gunshot exposures per year. Results revealed that hearing sensitivity for frequencies 3.0, 4.0, and 6.0 kHz for both ears in the experimental group was an average of approximately 5 to 10 dB poorer than that of the control subjects. Although both subject groups demonstrated poorer 3.0-to-6.0-kHz hearing sensitivity for left-ear compared with right-ear listening, the degree of asymmetry between ears was greater for the experimental subjects. Older shooters had more hearing loss and greater threshold asymmetry than younger shooters, but there was no significant relationship between hearing sensitivity and the number of unprotected exposures per year. This latter finding was attributed to a fourfold increase in the number of unprotected annual exposures that were reported by younger shooters, who had inherently better hearing than did the older shooters.

Adult↗
PubMed2000

[Ablation therapy with gentamycin in the treatment of Meniere's disease].

Historically the therapy for untreatable Ménière's disease (Md) has been surgery: conservative (cochleosacculotomy and decompression or sacco-endolymphatic shunt) or radical (labyrinthectomy and vestibular neurectomy). A valid alternative to surgery is the use of ototoxic drugs such as aminoglycoside antibiotics based on the assumption that some of the drugs exert greater ototoxicity vs. the posterior labyrinth. The purpose of the present study was to verify a severe protocol for the intratympanic administration of gentamicin sulfate in the treatment of Md unresponsive to medical treatment. A total of 29 patients were recruited for the study, all suffering from monolateral Md with reduced or normal (i.e. not absent) vestibular reflectivity on the side involved. The protocol called for audiovestibular testing prior to the treatment cycle and then 7 days after the administration of each individual dose. The same treatment scheme was used in all patients: a weekly intratympanic injection of gentamicin, 16 mg/per dose, for a maximum of 2 or 3 treatments. Of these cases, 20 have been followed up for 2 or more years and these are described in the present study. The follow-up called for suspending treatment and then repeating the audiovestibular tests every six months. Equilibrium was fully controlled in 70% of the patients while control was substantial in 30%. Audiometry showed that the auditory threshold remained unchanged in 60% of the cases while it worsened in 20% and, surprisingly, improved in the remaining 20%. In two cases deafness arose after the second treatment. The vestibular tests showed an uncompensated areflexia on the treated side after the therapeutic cycle although, in all cases, this had been compensated by the time of observation at 24 months. Symptoms of deafness remained unchanged. In conclusion, with respect to other more invasive treatments, chemical labyrinthectomy is simpler to perform and has fewer side effects while producing analogous clinical results.

Adult↗
PubMed2002

Olfactory acuity and cognitive function converge in older adulthood: support for the common cause hypothesis.

Visual and auditory thresholds and cognitive variables have shown converging losses in old age, which might exist because standard cognitive tests rely on these modalities for assessment. The present study investigated the common cause hypothesis in another sensory modality. Structural equation modeling tested the fit of a model representing the common cause hypothesis for olfactory acuity and cognitive function data from 98 nondemented older adults and 103 younger adults. The model fit better the data from the older adults, consistent with the common cause hypothesis. In addition, unique influences of age beyond those shared between cognitive and sensory variables were also demonstrated. The results suggest that olfactory functioning may be a valid indicator of the integrity of the aging brain in older adults.

Adolescent↗
PubMed2000

Effects of exposure to trichloroethylene and noise on hearing in rats.

Four groups of rats (n=8 per group) were exposed to either 3000 ppm trichloroethylene (TCE) alone or to 95 dB SPL noise alone or to the combination of TCE and noise or to control conditions. Exposure was carried out 18 hours/day, 5 days/week for 3 weeks. Exposure to TCE alone resulted in hearing loss at 4, 8, 16 and 20 kHz, but not at 24 and 32 kHz. Hearing loss due to exposure to noise alone occurred at frequencies of 8, 16 and 20 kHz. In general, combined exposure to TCE and noise resulted in larger auditory threshold changes than that produced by either TCE alone or noise alone when measured 1 and 2 weeks after the completion of exposure. For frequencies of 8, 16 and 20 kHz, hearing loss due to combined TCE-noise exposure was not larger than the algebraic sum of hearing loss due to exposure to TCE or noise alone. However, at a frequency of 4 kHz, hearing loss due to combined exposure was significantly larger than that produced by TCE exposure alone or noise alone, which itself had no effect at this frequency. These results suggest evidence of an interaction of combined exposure to TCE and noise at the lower edge of the range of frequencies affected.

Journal Article↗
PubMed2003

[Endoscopic technique utilized into the selective vestibular neurotomy by retrosigmoid approach].

OBJECTIVE: To investigate the micro-wound technique and the signification of reducing brain tissue oppression and complication at the surgery with utilizing endoscopic technique during the operation of selective vestibular neurotomy (SVNT) by retrosigmoid approach. METHODS: Twelve patients were preceded the SVNT by retrosigmoid approach (as routine operation group, ROG), and nine patients were utilized endoscope for review and neurotomy during the process of the SVNT by retrosigmoid approach (as endoscopic operation group, EOG). All of them were examined by auditory level, vestibular function, facial nerve function and observed of clinical situation (including complication and equilibrium function and so on) before and after operation. RESULTS: Two patients appeared cerebral edema and demanded the treatment of dehydration and depressing intracranial pressure in ROG after operation. In each group, the average auditory threshold in 2 patients rose more than 15 dB post-operation. The interval time of average equilibrium function compensation is (29.00 +/- 9.60) d in ROG and (28.56 +/- 7.91) d in EOG after surgery. Peripheral facial paralysis didn't happen to any patient in two groups. After follow-up two years post-operation, the vertigo recurred in 2 patients (4 times and 1 times, respectively) in ROG and 1 patient (2 times) in EOG. CONCLUSIONS: The SVNT by retrosigmoid approach is widespread adopted presently as expedience and safe surgery method for Ménière's disease, and could effectively eliminate vertigo and simultaneously conserve the hearing function and the integration of facial nerve. This surgery process became micro-wound, more facility and safe following the endoscopic technique utilization, which could reduce the brain tissues depression and trauma and could not cause any of complications. Therefore, the endoscopic operation of the SVNT by retrosigmoid approach is worth to clinically popularize as the therapy method of vertigo for the patients of Ménière's disease, especially who associate with contralateral sensorineural hearing loss.

Adult↗
PubMed2003

Hearing results in stapes surgery using two different prosthesis.

AIM OF THE STUDY: Evaluation of hearing results after implantation of a fluoroplastic-platinum piston (FP) and of a titanium piston (T) with a shaft diameter of respectively 0.6 mm and 0.4 mm, in cases of otosclerosis requiring stapedotomy. MATERIAL AND METHODS: Pre-operative and post-operative hearing results obtained after primary stapedotomy by implantation of 30 FP and 30 T performed by the same expert author (C.Z.) were reviewed. In each patient we evaluated pre- and post-operative auditory thresholds, as recommended. RESULTS: All patients of both groups showed a significant air-bone gap (ABG) improvement for all frequencies after surgery ( P < 0. 001). Post-operative ABG comparison between the two groups showed a better ABG for lower frequencies in the FP group and for higher frequencies in the T group, but the difference was not significant. No post-operative complications, including sensorineural hearing loss, were found. Bone conduction improvement was better in the FP group than in the T one and this difference was statistically significant at 1000 and 2000 Hz. There was no statistically significant difference in the post-operative outcomes between the two prosthesis. Better results of FP for lower frequencies suggest that an increase in diameter of the prosthesis results in a greater improvement in the hearing threshold at low frequencies, while a decrease of diameter results in a greater improvement in the hearing threshold at high frequencies, as indicated by previous international studies. CONCLUSION: Our data shows that titanium piston is a as good as fluoroplastic piston in stapes surgery for otosclerosis.

Adult↗
PubMedDate not supplied

[Indirect electric stimulation of the auditory neural structures in the complex treatment of sensorineural hearing loss and subjective noise in the ears].

Indirect or transdermal electrostimulation (ES) was used in 62 patients suffering from neurosensory hypoacusis stage II-III. The procedure was conducted with the help of an +electric stimulator made on the country and a device providing an automatic change of the polarity. Disappearance of noise in the ears, better hearing, 10-15 dB shifts in auditory thresholds were achieved in 20 patients (32.3%). Noise in the ears declined, hearing improved subjectively in 25 (40.3%) of the patients. 17 (27.4%) of the patients did not respond. ES is recommended as a method of choice in combined treatment of neurosensory hypoacusis and subjective noise in the ears.

Cochlear Nerve↗