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Results for “Auditory Threshold”

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PubMed2003

Internet application to tele-audiology--"nothin' but net".

The Telehealth program at East Carolina University has developed a system for real-time assessment of auditory thresholds using computer driven control of a remote audiometer via the Internet. The present study used 45 adult participants in a double-blind study of 2 different systems: a conventional audiometer and an audiometer operated remotely via the Internet. The audiometric thresholds assessed by these 2 systems varied by no more than 1.3 dB for air conduction and 1.2 dB for bone conduction. The results demonstrated the feasibility of this new "telehearing" audiometric system. With the rapid development of Internet-based applications, telehealth has the potential to provide important healthcare coverage for rural areas where specialized audiological services are lacking.

Adult↗

PubMed2002

Otosclerosis and stapedoplasty in older adults.

OBJECTIVES: To evaluate the efficacy of stapedoplasty in patients aged 60 and older, based on audiometric data and a questionnaire about quality of life. DESIGN: A retrospective (1994-2000) study. SETTING: People living in southern and central Italy. PARTICIPANTS: Sixty-three patients: 32 consecutive patients aged 60 and older (group 1) and 31 consecutive patients younger than 60 (group 2). MEASUREMENTS: In each patient, we evaluated the pre- and postoperative auditory thresholds. Each patient answered a questionnaire about postoperative quality of life. RESULTS: When comparing the pre- and postoperative air conduction thresholds and air-bone gap in the patients aged 60 and older, a statistically significant (P <.001) improvement at each frequency was observed. When elaborating the answers to the questionnaire about postoperative quality of life, we noticed that the older patients experienced a greater improvement. CONCLUSION: The results show that stapedoplasty offers greater improvement in quality of life for selected adults aged 60 and older than for younger adults. The operation also appears to be as safe for adults aged 60 and older as for younger adults. Stapedoplasty provides subjects with satisfactory social hearing level (hearing capacity sufficient for normal social relations) and slows the progression of otosclerosis. Providing older patients with good auditory functionality improves their state of health, quality of life, and cognitive processes.

Aged↗

PubMedDate not supplied

The prognostic value of electrocochleography in severely hearing-impaired infants.

This paper presents a longitudinal evaluation of electrocochleographic assessment in severely hearing-impaired infants. Electrophysiological data were obtained by transtympanic electrocochleography to tone-burst stimuli at octave frequencies of 500 to 8000 Hz at the age of 0-6 years in a group of 126 subjects. The results are compared with auditory thresholds determined at school age in the same children by means of pure-tone audiometry. Cochlear microphonics could be recorded in virtually all ears, although the majority of subjects had hearing losses of 90 dB and more. Compound action potentials (CAPs) showed waveforms varying from normal to a wide range of abnormalities. Audiometric thresholds correlated generally well with the compound action potential (CAP) thresholds obtained in infancy. The error in the predicted audiometric thresholds is between 15 and 20 dB, as compared with 11 dB reported for more moderate hearing losses. It is shown that, in spite of the high stimulus levels used, substantial frequency-specific threshold information is retained. Occasional large discrepancies in thresholds were often associated with markedly abnormal response waveforms. Among the many cases in which no ABR could be elicited, 68 per cent produced detectable electrocochleographic responses in the 1000-4000 Hz range. It is concluded that electrocochleography is a valuable method for the assessment of residual hearing in infants suspected of having a severe hearing impairment.

Audiometry, Evoked Response↗

PubMed1980

Clinical considerations in the interpretation of auditory brainstem response audiometry.

Auditory brainstem response (ABR) audiometry which monitors the electrical activity of the auditory nerve and brainstem nuclei, has provided a new technique in the diagnosis of neurological dysfunction and peripheral hearing deficits. Brainstem potentials consist of seven waves, each separated in latency by approximately one millisecond and each representing successively higher order neuron activity of the auditory pathway. The criteria used for ABR interpretation are based primarily on the latency of individual were peaks and their interpeak latencies. Due to its consistency and stability, the fifth wave has been considered prominent in the interpretation of auditory threshold sensitivity. Unfortunately, Wave V latency-intensity function may be affected by extrinsic and intrinsic variables. Consequently, in order to establish diagnostic criteria that are comparable, the elimination and/or control of these variables must be examined. Therefore, the purpose of this paper is to report the effects of various pathological and nonpathological conditions which contribute to difference in ABR audiometry interpretation.

Acoustic Stimulation↗

PubMed2005

Sensitivity of a tucuxi (Sotalia fluviatilis guianensis) to airborne sound.

Auditory systems of cetaceans are considered highly specialized for underwater sound processing, whereas the extent of their hearing capacity in air is still a point of issue. In this study, the sensitivity to airborne sound in a male tucuxi (Sotalia fluviatilis guianensis) was tested by means of a go/no go response paradigm. Auditory thresholds were obtained from 2 to 31.5 kHz. Compared to the hearing thresholds of other dolphins as well as of amphibian mammals, the sensitivity to airborne sound of the test subject is low from 2 to 8 kHz, with the highest threshold at 4 kHz. Thresholds at 16 and 31.5 kHz reveal a sharp increase in hearing sensitivity. Thus, although not obtained in this study, the upper aerial hearing limit is in the ultrasonic range. A comparison of the present data with the underwater audiogram of the same test subject referred to sound intensity indicates that the sensitivity of Sotalia to underwater sound is generally better than to airborne sound.

Air↗

PubMed1998

Underwater audiogram of a tucuxi (Sotalia fluviatilis guianensis).

Using a go/no go response paradigm, a tucuxi (Sotalia fluviatilis guianensis) was trained to respond to pure-tone signals for an underwater hearing test. Auditory thresholds were obtained from 4 to 135 kHz. The audiogram curve shows that this Sotalia had an upper limit of hearing at 135 kHz; from 125 to 135 kHz sensitivity decreased by 475 dB/oct. This coincides with results from electrophysiological threshold measurements. The range of best hearing (defined as 10 dB from maximum sensitivity) was between 64 and 105 kHz. This range appears to be narrower and more restricted to higher frequencies in Sotalia fluviatilis guianensis than in other odontocete species that had been tested before. Peak frequencies of echolocation pulses reported from free-ranging Sotalia correspond with the range of most sensitive hearing of this test subject.

Animals↗

PubMed2006

Stability of low-frequency residual hearing in patients who are candidates for combined acoustic plus electric hearing.

The purpose of this study was to investigate the stability over time of low-frequency auditory thresholds to better determine if the new technique of using a short-electrode cochlear implant that preserves residual low-frequency acoustic hearing can be a long-term solution for those with severe-to-profound hearing loss at high frequencies. The present study determined the long-term rate of decline in acoustic hearing in patients who have a preexisting hearing loss yet have not been implanted with a cochlear implant. A retrospective analysis of patients' audiograms that fit into the range for candidacy for the short-electrode device was performed to calculate the rate of change of threshold over time. The analysis of adult patients' data indicated that there was an average of only 1.05 dB hearing deterioration per year in the low frequencies and that presbycusis accounted for approximately one third to one half of this decline. The average deterioration of hearing threshold for pediatric patients was 1.2 dB per year; however, the rates of change in pediatric patients were considerably more variable (across individuals and across frequencies) than in adults. These data provide support for the idea that the short-electrode cochlear implant may be a practical solution for most adults in the long run, but this may not be the case for all pediatric patients.

Acoustic Stimulation↗

PubMed1988

Middle latency response to a 500-Hz tone pip in normal-hearing and in hearing-impaired subjects.

Measurement of middle latency responses (MLR) appears to be one of the most useful ways of determining low-frequency auditory threshold. It is known that analog filtering can drastically affect MLR and since most laboratories use different recording characteristics, we carried out these measurements with a number of filter configurations. Ten subjects with normal hearing sensitivity were tested. The stimuli were 500-Hz tone pips (alternating in polarity) with a 4-ms rise-fall time and a plateau of 2 ms, presented at the rate of 9.3/s. The MLR were recorded with filter settings of 10-100, 10-250, 10-1,500, 10-3,000, 30-100 and 30-250 Hz at 12 dB per octave roll-off with a time base of 100 ms. MLR threshold was found between 8.0 and 11.5 dB nHL. The Wilcoxon statistical test showed that mean MLR thresholds did not differ significantly at the various bandpass configurations. An additional objective of this study was to compare hearing sensitivity based on MLR threshold to tone pips at 500 Hz and behavioural results obtained by conventional pure-tone audiometry. Although the correlation coefficient between the behavioural and electrophysiological measurements was statistically significant (r = 0.85), further studies are required in order to determine the real magnitude of the predicted errors obtained, before this electrophysiological measure can be applied clinically.

Adolescent↗

PubMed2002

[Follow-up assessment of intratympanic gentamicin therapy and Saccotomia in Menière's Disease].

BACKGROUND: The intratympanic application of ototoxic antibiotics and saccotomia have been well documented in severe cases of one-sided Menière's disease for 30 years now. Both treatment methods are still subject to controversial discussion. PATIENTS AND MATERIAL: This study includes 8 patients suffering from persistent one-sided Menière's disease after treatment with gentamicin application and additional saccotomia (n=2). We performed follow-up visits including the assessment of hearing ability, vestibular function and cranial MRI, 2-10 years after onset of treatment. RESULTS: After therapeutic interventions 7 patients reported to be healed of their symptom vertigo. In 4 patients the gentamicin-treated vestibular organ did not respond to thermic stimulus at the time of follow-up examination. Auditory threshold shift was observed in 3 patients (1 permanent, 2 temporary), whereas hearing threshold improved in 2 patients. Tinnitus was attenuated in 3 patients, while 1 patient suffered from posttherapeutic onset of tinnitus. Morphological and structural changes due to Menière's disease and treatment procedures were ruled out by cranial MRI. CONCLUSION: The intratympanic application of ototoxic medication is a safe and effective treatment method in severe cases of Menière's disease. Saccotomia should be considered as therapeutic regimen for persistent symptoms after repeated application of gentamicin.

Aged↗

PubMedDate not supplied

Effects of toluene inhalation on detection of auditory signals in rats.

Inhalation of organic solvents can affect vigilance and reaction time in humans. An animal model of vigilance was designed to assess the effects of toluene on these processes. Adult male Long-Evans rats were trained to detect auditory signals (20-msec increases in the intensity of white noise). Two to 4 s after each signal (or blank period), two retractable levers were inserted into the test chamber. A press on one lever after a signal and on the other lever after a blank resulted in the delivery of food. Signal detection analysis showed that sensitivity (Sensitivity Index, SI) and response bias (Responsivity Index, RI) increased with signal intensity, indicating that loud signals were more detectable than soft signals and that the animals' criterion for responding "signal" increased with signal intensity. Response latency for correct choices was faster for signal trials than for blank trials. Toluene vapor was added to the airstream of these chambers at concentrations of 0, 1000, 1500, or 2000 ppm, either 10 or 30 min before testing and for the duration of each 1-h test. In air, SI increased across the duration of the test; this within-session improvement was reversed by toluene. RI did not change in air; it was decreased by toluene at the beginning of each exposure session, returned to the control level during exposure to 1000 and 1500 ppm toluene and exceeded air control after 40 min exposure to 2000 ppm toluene. Latency increased monotonically across toluene concentrations and time on test. Neither signal intensity nor the duration of toluene exposure before testing altered these effects of toluene. SI, RI, and latency baselines were recovered after toluene exposure indicating that no persistent effects of toluene were detectable. This conclusion was supported by data from other rats showing that toluene exposure (2000 ppm for 2 h/day for 4 consecutive days) did not affect auditory thresholds, as determined by reflex modification of an acoustic startle response using a 16 kHz tone as a prepulse stimulus, 7 or 17 days after exposure to toluene. Finally, rats tested immediately or 20 min after exposure to 0, 1000, 1500, or 2000 ppm toluene were not affected by the vapor, indicating that the impairment observed during toluene inhalation did not persist beyond the period of exposure.

Administration, Inhalation↗

PubMed1981

A psychophysical investigation of auditory functioning in schizophrenia.

The present report is of the application of Treisman's (1964) model of perceptual functioning to the study of schizophrenic hallucinations. It was hypothesized that hallucinators would perform on an auditory threshold task as if possessing a perceptual system showing high levels of spontaneous neural activity (In). Three groups were compared on the Weber functions for pure tone intensity: schizophrenic hallucinators, old people and anxiety neurotics. From these functions, estimates of In were calculated using Barlow's (1957b) method. No group differences were found. An alternative explanation of schizophrenic hallucinations, in terms of increased responsiveness to normal levels of background sensory activity, is proposed.

Adult↗

PubMed1999

Labyrinthine fenestration in the guinea pig.

OBJECTIVE: To evaluate the auditory effects of single, double, and triple semicircular canal fenestration procedures, with and without sealing the labyrinthine defect. BACKGROUND: Violation of the inner ear remains a feared complication in otologic surgery because it commonly leads to profound sensorineural hearing loss. It has been assumed that the natural history of labyrinthine injury in the guinea pig is similar to that in human beings; however, this assumption has not been rigorously studied. DESIGN: Prospective, randomized, and controlled animal study. SUBJECTS: Sixty pigmented guinea pigs. OUTCOME: Click-evoked electrocochleographic response, with same-ear prefenestration control. RESULTS: All of the fenestration groups had elevated auditory thresholds at 1 hour when compared with controls (P < 0.01); however, this difference lost statistical significance at 1 and 4 weeks. The degree of labyrinthine injury did not correlate with the degree of hearing loss or with the incidence of anacusis. Hearing remained stable during the study period. Sealing the fenestration had no significant audiologic effect (P > 0.40). CONCLUSIONS: The guinea pig model of labyrinthine fenestration may not be representative of the human condition.

Animals↗

PubMedDate not supplied

Mid-frequency hearing loss in rats following inhalation exposure to trichloroethylene: evidence from reflex modification audiometry.

The present experiments were undertaken to characterize the hearing loss associated with 1,1,2-trichloroethylene (TCE) exposure. Adult male Long-Evans (LE) rats were exposed to TCE via inhalation (whole body) for 6 h/day for 5 days. The concentration-effect function (0-4000 ppm) was determined 3 weeks post-exposure. Animals were tested for auditory thresholds to 4, 8, 16, 24, 32, and 40-kHz tones using reflex modification audiometry. In a separate experiment, the time course of effects was determined by monitoring 16-kHz thresholds prior to, 1 h following each of the 5 exposure days, and 5 days, 1, 2, 4, 8, and 12 weeks post-exposure. At 14 weeks, these same animals were tested for thresholds to 0.5, 1, 2, 4, 8, 16, 24, 32, and 40-kHz tones. Results indicate elevated thresholds (hearing loss) for the 4000 ppm group at 8 and 16 kHz of approximately 18 and 30 dB, respectively. Time-course data demonstrated a rapid onset, a 20-dB loss at 16 kHz after the fifth exposure day, and a 40-dB loss by 2 weeks that persisted up to 14 weeks post-exposure. These data demonstrate an atypical and persistent, mid-frequency hearing loss in rats following inhalation exposure to TCE.

Administration, Inhalation↗

PubMed2006

Mice expressing constitutively active Gsalpha exhibit stimulus encoding deficits similar to those observed in schizophrenia patients.

People with schizophrenia display sensory encoding deficits across a broad range of electrophysiological and behavioral measures, suggesting fundamental impairments in the ability to transduce the external environment into coherent neural representations. This inability to create basic components of complex stimuli interferes with a high fidelity representation of the world and likely contributes to cognitive deficits. The current study evaluates the effects of constitutive forebrain activation of the G(s)alpha G-protein subunit on auditory threshold and gain using acoustic brainstem responses and cortically generated N40 event-related potentials to assess the role of cyclic AMP signaling in sensory encoding. Additionally, we examine the ability of pharmacological treatments that mimic (amphetamine) or ameliorate (haloperidol) positive symptoms of schizophrenia to test the hypothesis that the encoding deficits observed in G(s)alpha transgenic mice can be normalized with treatment. We find that G(s)alpha transgenic mice have decreased amplitude of cortically generated N40 but normal acoustic brainstem response amplitude, consistent with forebrain transgene expression and a schizophrenia endophenotype. Transgenic mice also display decreased stimulus intensity response (gain) in both acoustic brainstem response and N40, indicating corticofugal influence on regions that lack transgene expression. N40 deficits in transgenic animals were ameliorated with low dose haloperidol and reversed with higher dose, suggesting dopamine D2 receptor-linked Gi activity contributes to the impairment. Consistent with this hypothesis, we recreated the G(s)alpha transgenic deficit in wild type animals using the indirect dopamine agonist amphetamine. This transgenic model of sensory encoding deficits provides a foundation for identifying biochemical contributions to sensory processing impairments associated with schizophrenia.

Acoustic Stimulation↗

PubMed2004

Vitamin E reduces cisplatin ototoxicity.

OBJECTIVES/HYPOTHESIS: Cisplatin ototoxicity is a major dose-limiting factor in the treatment of several neoplasms. Vitamin E, a slow-acting free radical scavenger, has been shown to ameliorate nephrotoxicity and endothelial cell damage in animals receiving cisplatin. The purpose of the study was to determine the effectiveness of vitamin E as an otoprotectant. STUDY DESIGN: Prospective, randomized controlled trial in the rat model. METHODS: Wistar rats (weight, 261-386 g) were sedated using 172.4 mg/kg intramuscular ketamine and 3.4 mg/kg xylazine. Baseline auditory brainstem response (ABR) testing was performed in response to clicks and 8-, 16-, and 32-kHz tone bursts. After auditory thresholds were determined, the animals received intraperitoneal drug administration according to one of three group classifications. Group 1 received 4 g/kg vitamin E followed after 30 minutes by 16 mg/kg cisplatin. Group 2 received 6 mL/kg soybean oil followed after 30 minutes by cisplatin. Group 3 received soybean oil followed after 30 minutes by 16 mL/kg saline. After 3 days' follow-up, ABR testing was performed and threshold changes were recorded. Cochleae were removed and processed for scanning electron microscopy after follow-up auditory testing was carried out. RESULTS: Group 2 animals showed marked hearing loss with average threshold shifts of 28.75 +/- 2.3 dB for clicks, 30.0 +/- 1.9 dB at 8 kHz, 21.25 +/- 4.0 dB at 16 kHz, and 45.0 +/- 4.2 dB at 32 kHz. No significant loss was observed in group 3 with shifts of 2 +/- 1.3 dB, 3 +/-3.0 dB, -2.2 +/- 3.1 dB, and -1.1 +/- 4.0 dB for clicks and tone bursts at 8, 16, and 32 kHz, respectively. Significant protection was seen in group 1 animals compared with group 2 animals. In the former group, threshold shifts of 12.5 +/- 3.1 dB for clicks, 7.5 +/- 2.5 dB at 8 kHz, 5.0 +/- 3.3 dB at 16 kHz, and 24.4 +/- 5.6 dB at 32 kHz were observed. These findings were supported by the scanning electron microscope observations that severe outer hair cell destruction occurred in group 2 rats, whereas outer hair cells were preserved to a much greater extent in the cochleae of rats in group 1 that were pretreated with vitamin E. CONCLUSION: Vitamin E appears to have a protective effect against cisplatin ototoxicity.

Animals↗

PubMed1979

Neurotological studies on Meniere's disease and sudden deafness.

During the period from January 1973 to June 1975, 60 cases with definite Meniere's disease and 30 cases with sudden deafness were listed according to such criteria for the diagnosis of both diseases as determined by the Research Committee of Japan. A neurootological assessment for both diseases were performed in our series. In patients with definite Meniere's disease, hearing impairment was characterized by deficiency in detecting low- and middle-pitched tones and fluctuation of auditory threshold in low frequency range. In sudden deafness, highly impaired hearing loss, i.e., total deafness, was frequently observed (45%). However, recruitment occurred at the same incidence (80%) in both diseases tested. The incidence of spontaneous nystagmus was almost the same regardless of associated vertigo and the course of both diseases. Moreover, it was also recognized that a reduction of caloric responses was a better indication for assessment of the affected ear in both diseases.

Audiometry↗

PubMed1992

Hippocampal auditory evoked response threshold in the rat: behavioral modulation.

Summed auditory evoked responses (AERs) were recorded bipolarly from CA1 field and inner molecular layer of the dentate gyrus of the hippocampus (Hipp) and compared to AERs simultaneously recorded from other extralemniscal (EL) nuclei and the inferior colliculus (IC) in the rat. There were no significant threshold differences for early Hipp AER (EHAER) and other EL AERs. The threshold for EHAERs and other EL AER was by several tens of decibels above that for IC, but usually lower than that for eliciting muscular reflexes. Actual behaviour (still waking, drowsiness, exploration, attention to stimuli) modified the thresholds for EHAER and other EL AERs equally. There was only little effect of actual behavior upon nonthreshold modulation of amplitudes of EHAERs. It is assumed that setting the threshold of the hypothetical common source of EH and other EL AERs plays main role in their behavioral modulation. As supposedly EHAERs are mediated through the perforant path, our results suggest that this pathway might transmit information related to high-threshold diffuse activation of the brain during the early stage of auditory processing.

Acoustic Stimulation↗

PubMed2005

Off-axis sonar beam pattern of free-ranging finless porpoises measured by a stereo pulse event data logger.

The off-axis sonar beam patterns of eight free-ranging finless porpoises were measured using attached data logger systems. The transmitted sound pressure level at each beam angle was calculated from the animal's body angle, the water surface echo level, and the swimming depth. The beam pattern of the off-axis signals between 45 degrees and 115 degrees (where 0 degrees corresponds to the on-axis direction) was nearly constant. The sound pressure level of the off-axis signals reached 162 dB re 1 microPa peak-to-peak. The surface echo level received at the animal was over 140 dB, much higher than the auditory threshold level of small odontocetes. Finless porpoises are estimated to be able to receive the surface echoes of off-axis signals even at 50-m depth. Shallow water systems (less than 50-m depth) are the dominant habitat of both oceanic and freshwater populations of this species. Surface echoes may provide porpoises not only with diving depth information but also with information about surface direction and location of obstacles (including prey items) outside the on-axis sector of the sonar beam.

Acoustics↗