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 631 records · Page 35Linked to original sources

PubMed1981

Electrophysiological study of the maturation of auditory responses from the inner ear of the chick.

Three electrophysiological functions of the chick basilar papilla were studied during development by recording the compound actin potential (AP) at the round window. The auditory thresholds showed a continuous maturation between the fifteenth day of incubation (E15) and the first post-hatching day (P1), when they attained adult values. Responses matured first to low frequencies and later to high frequency stimuli. The input-output (intensity-amplitude) functions matured regularly and never demonstrated the classical two slopes seen in mammals. The tuning properties, studied by tone-on-tone masking of the AP, achieved mature values before the thresholds; the Q10s reached adult values at E17 for a 500-Hz probe tone and at E19 for a 1000-Hz probe tone. The fact that a low-to-high frequency development trend was found with the embryonic middle ear cleared of fluids further suggests that this property of auditory ontogeny may be a function of changes in the transduction properties of the cochlea.

Aging↗

PubMed2003

[Automated hearing threshold estimation in newborns using extrapolated DPOAE input/output functions].

BACKGROUND AND AIM: A new method for automatically assessing hearing loss by means of extrapolated DPOAE I/O-functions was applied for the first time in newborns. METHODS: DPOAE I/O-functions were recorded in 118 ears of 93 newborns (mean age 3 days) at 12 frequencies between 1 and 8 kHz. L(2) was varied between 20 and 65 dB SPL with L(1)=0.4L(2)+39 and f(2)/f(1)=1.2. Auditory thresholds were constructed using the estimated DPOAE threshold level from extrapolated DPOAE I/O-functions. Follow-up measurements were conducted in 15 ears 4 weeks later. RESULTS: The first measurement revealed a high-frequency hearing loss. The second measurement showed normal hearing function. This fact and the decrease of DPOAE level in the frequency range of the hearing loss, while keeping the compressive shape of the DPOAE I/O-functions, indicate that transitory sound conduction disturbance may be due to amniotic fluid. CONCLUSIONS: The method fulfils the essential criteria for screening newborn hearing. It is fast and easy to handle, and measurement and data analysis are performed automatically. Preliminary results suggest that the new method is able to differentiate between transitory middle-ear dysfunction and persisting cochlear disorders. Due to its better diagnostic capabilities in comparison to TEOAE, DPOAE, and FAEP, this method may provide a new instrument with which to make a fast evaluation of hearing function in children.

Acoustic Stimulation↗

PubMed2000

A modified pure tone audiometry technique for medico-legal assessment.

A modified method of pure tone audiometry (PTA) in which the auditory threshold is approached from silence in ascending steps, with tone presentations of 1-4 seconds and interval durations of 1.5-5 seconds was assessed against the British Society of Audiology (BSA) method of PTA in terms of its ability to establish valid thresholds in cases of non-organic hearing loss, prevalent in medico-legal testing. The results reveal that the modified technique of PTA is a valid threshold measurement for honest subjects, and yields less non-organic overlay than the standard method of PTA in cases of non-organic hearing loss.

Adult↗

PubMed1979

Hearing loss from simulated work-week exposure to impulse noise.

Six monaural chinchillas were exposed to a repetitive, reverberant, impulse noise for a total of five days, 8 h per day. The average peak overpressure within the holding cage was 113 dB. The reverberation time (pressure fluctuation envelope within 20 dB of peak) was 160 ms. Auditory thresholds were measured at 0.25, 0.5, 1, 2, 4, and 8 kHz before and after each day's exposure using either the average-evoked response technique or shock avoidance conditioning. After the last exposure, recovery was monitored for five successive days. Final thresholds were obtained starting at 30 days postexposure after which the animals were sacrificed for cochlear histology. The high frequencies (4, 8 kHz) showed a daily median shift of 40 dB and a 27 dB recovery before the following day's exposure. The low frequencies (0.25, 0.5 kHz) were shifted 35 dB after each day's exposure with a 15 dB recovery overnight. Final median audiograms showed little permanent threshold shift. The cochleagrams for two test animals were found to be normal while the remaining four displayed 10%--40% losses in hair cells at specific cochlear sites.

Animals↗

PubMed2005

Post-exposure treatment attenuates noise-induced hearing loss.

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are involved in sensory cell and neural death in the peripheral nervous system, including damage induced by noise trauma. Antioxidant administration prior to or concomitant with noise exposure can prevent auditory deficits, but the efficacy of a delayed treatment is not known. We have recently found continued reactive oxygen species/reactive nitrogen species formation in the ear for 7-10 days following noise exposure and reasoned that antioxidant intervention during this period should also reduce noise-induced hearing loss. Guinea-pigs were subjected to 4 kHz octave band noise at 120 decibels sound- pressure-level (dB SPL) for 5 hours and received treatment with ROS and RNS scavengers (salicylate and trolox) beginning 3 days prior, 1 hour, 1, 3, or 5 days after noise exposure. Auditory thresholds were assessed by sound-evoked auditory brainstem response at 4, 8, and 16 kHz, before and 10 days after noise exposure. Hair cell damage was analyzed by quantitative histology, and free radical activity was determined immunohistochemically via 4-hydroxynonenal and nitrotyrosine as markers of reactive oxygen species and reactive nitrogen species action. Delivered up to 3 days after noise exposure, salicylate and trolox significantly reduced auditory brainstem response deficits, reduced hair cell damage, and decreased reactive oxygen species and reactive nitrogen species formation. Earlier drug treatment was more effective than later treatment. Our results detail a window of opportunity for rescue from noise trauma, and provide evidence for both morphological and functional protection by delayed pharmacological intervention.

Aldehydes↗

PubMed1996

Unusual presentations of acoustic tumours.

A series of 238 consecutive patients with acoustic neuromas, operated on in Paris has been studied to identify unusual presentations and varied symptomatology. The most common history was that of a progressive unilateral hearing loss (in 68.1%), with tinnitus (in 49.1%) or disequilibrium (in 49.1%) or both. Sudden hearing loss (in 14.7%) or fluctuating hearing loss (in 6.3%), and a single or repeated episodes of acute vertigo (in 8.8%) were seen less commonly. Headaches occurred as an associated symptom in 10.5%, tinnitus was the sole symptom in 2.8% and other uncommon symptoms included otalgia, facial nerve palsy, facial or ocular pain, altered sensation in the face or eye, or tingling of the tongue. Some 11.3% of patients presented with normal pure tone auditory thresholds and a 100% speech discrimination score and of these patients acoustic reflex thresholds were normal in 53% and brainstem auditory evoked responses were suggestive of the retro-cochlear abnormality in only 76.2%. Amongst the less common presentations, the initial symptoms mimicked such diagnoses as Meniére's disease, benign positional vertigo, vertebro-basilar migraine, vertebro-basilar insufficiency, Bell's palsy and Trigeminal neuralgia. Overall, 20.6% of patients had unusual initial presenting symptoms, 36.5% of the symptoms were unusual and these were found in isolation in 11.8% of patients. An awareness of the spectrum of more subtle symptoms of acoustic tumours may lead to the correct diagnosis at an earlier stage.

Aged↗

PubMed1998

Age and the human cochlear traveling wave delay.

OBJECTIVE: Cochlear physiologic changes that occur with aging also may affect the mechanics and filtering properties of the cochlea. In studying aging effects, it is also necessary to consider the effects of hearing threshold losses because thresholds generally increase with age, and threshold losses also affect the filtering properties of the cochlea. A distortion product emission (DPE)-based measurement of human cochlear traveling wave delays allows an indirect assessment of the mechanics of the traveling wave and how it might change with age. DESIGN: The cochlear traveling wave delay has been derived from DPE phase measurements using an f1 sweep paradigm (Kimberley, Brown, & Eggermont, 1993). In the present study, traveling wave delay was estimated from DPE phase measurements taken from the left ears of 91 subjects (22 to 78 yr) with auditory thresholds ranging from normal hearing (< or = 25 dB SPL, ANSI 1969) to mild cochlear hearing damage. No one under the age of 65 had hearing losses exceeding 40 dB SPL to 8 kHz. Pure-tone thresholds were determined at eight frequencies through a 4-interval, forced-choice, adaptive-level psychophysical test. DPE phase and amplitude measurements were made at these eight frequencies using CUBeDIS-related software (AT&T Bell Labs). Round-trip traveling wave estimates were calculated from the DPE phase measurements for each of the eight f2 frequencies (places). RESULTS: Traveling wave delays estimated using DPE phase were not significantly affected by mild hearing losses. Traveling wave delay, however, does increase slightly with age. Optimal f2/f1 ratio and associated DPE amplitude also were tested for age or threshold effects. The optimal f2/f1 ratio remained unaffected by age or hearing loss but decreased with increasing frequency. The maximum DPE amplitude decreased with both advancing age and increasing pure-tone threshold, so it was impossible to isolate the contribution of each individual factor. CONCLUSIONS: Mild hearing losses do not affect the round-trip traveling wave delay. There is a slight age dependence, however. This may suggest that there are age-related but threshold-independent factors that may alter such properties as basilar membrane stiffness or cochlear fluid composition. The relationship between maximum DPE amplitude and threshold, at the frequencies tested, is a better predictor of hearing thresholds than the DPE amplitude as obtained from a fixed ratio DPE amplitude measurement.

Adult↗

PubMed1990

[Effects of body posture on cochlear performance].

Experimental research has demonstrated that changes in body position influence auditory function and, specifically, supine position produces a sensorineural hearing loss at low frequencies. The hypotheses to interpret these phenomena are principally referred to an increase of hydrostatic pressure of labyrinthine fluids. In order to evaluate the effects of head position on the cochlear performance a modern test battery has been performed to study cochlear function in 11 normal subjects ranged in age from 22 to 34 years. The tests (Remote Masking:RM; Brief Tone Audiometry:BTA; Critical Ratio:RC) have been evaluated in two positions: sitting upright and supine with the head at a 20 backward angle. The results of our research have shown that in all the cases, the supine position produces a significant shift of the auditory threshold at 250 and 500 Hz, and a decrease of RM values in about all of the cases. We have estimated non statistically significant differences for the RC and BTA values, in more than half of the ears tested. On the basis of the significance given to RM, BTA, RC: we can deduce that the modifications of the auditory performance related to an increase in perilymphatic hydrostatic pressure, induced by the head position are produced by an increase in rigidity of the mechanical vibratory structures of the cochlea rather than the expression of sensorineural damage.

Adult↗

PubMed2003

Delayed loss of residual hearing in Clarion cochlear implant users.

Hearing threshold has been measured in a group of patients following cochlear implantation with a Clarion device for the last eight years. The patients had received either a pre-curved carrier or the Hi-Focus I plus Electrode Positioner System (EPS). The assessment was carried out within the first post-operative week as well as at a later stage, between six and 87 months, post-operatively. Residual hearing thresholds were still measurable early after surgery in 24.5 per cent of the patients, without differences between the two different Clarion models. However, the number of subjects with measurable hearing dropped to 16.3 per cent as observed when hearing was measured at a later stage, with an equal distribution between the two groups of patients. From this study it has been possible to observe that only a limited number of patients maintain residual hearing after Clarion cochlear implantation, and that this tends to decrease further over time. Nevertheless, the performance of these patients for speech tests did not appear to be affected by deterioration of the pure-tone auditory threshold.

Audiometry, Pure-Tone↗

PubMedDate not supplied

Reliability of slow vertex response audiometry in young children with sensorineural hearing loss.

In order to supplement our previous report on the reliability and validity of slow vertex response (SVR) audiometry, the detectability of the response, the agreement among scorers and test-retest reliability were studied in 6 children aged 2-4 years who have sensorineural hearing loss of 60-75 dB for the test frequency (1 000 Hz). Mean percentage of positive response increased from 20.6 to 62.2% as stimulus intensity was increased from 60 to 80 dB. Such a sharp increase in the detectability of the response at a level of stimulus intensity close to the auditory threshold of the subjects was not observed in normal children. The results indicate that SVR audiometry is more reliable and valid in children with sensorineural hearing loss than in normal children.

Acoustic Stimulation↗

PubMed1988

[Different forms of drug therapy for progressive sensorineural hearing loss in childhood].

Because of progressive sensorineural hearing loss 26 patients of the age of 2 to 19 years were treated for 10 days with infusions of prednisolone, pentoxifylline and piracetam. After this treatment improved, auditory thresholds were found in 58%. In comparison with a previous investigation (treatment with prednisolone and pentoxifylline except piacetam), no significant difference between these two methods of therapy was seen.

Adolescent↗

PubMed1997

Microphonic and DPOAE measurements suggest a micromechanical mechanism for the 'bounce' phenomenon following low-frequency tones.

Neural auditory thresholds in the guinea pig can be temporarily improved by up to 6 dB about 2 min after the cessation of an moderately intense low-frequency tone (Kirk and Patuzzi, 1997). We have measured changes in the f2-f1 distortion product otoacoustic emission (DPOAE) and low-frequency microphonic potential in scala tympani before, during and after a low-frequency tone (200 Hz) to determine the cause of this so-called bounce phenomenon. In particular we have analysed the low-frequency microphonic waveform in detail to estimate changes in the maximal receptor current through the outer hair cells (OHCs), the sensitivity of the OHC forward transduction process and the change in OHC operating point on the mechano-electrical transduction transfer curve. Our results indicate that a 200 Hz tone changes the maximal current and sensitivity of the OHCs minimally, but more importantly, it transiently changes the operating point on the OHC transfer curve. In particular, the operating point changes are consistent with a movement of the OHC stereocilia away from the OHC basal body at the peak of the bounce. These changes detected using the microphonic potential are associated with changes in the level of the f2-f1 DPOAE that correlate well with the electrical measurements. We suggest that the shift in operating point is largely responsible for the increase in cochlear sensitivity, and is due to a disruption of the salt balance within the cochlea during the intense low-frequency tone.

Acoustic Stimulation↗

PubMed1989

Hazard from an intense midrange impulse.

It has been hypothesized that the ear would become increasingly susceptible to impulses (gunfire) as the spectral peak of the impulse approached the frequency region where the ear was tuned best (about 4 kHz for the cat ear) [G. R. Price, J. Acoust. Soc. Am. Suppl. 1 62, S95 (1977)]. This prediction was counter to the predictions of the world's damage-risk criteria for impulse noise. It has been supported by experiments using exposures to 100-Hz and 800- to 1000-Hz impulses; but no test had been run at the point of predicted maximum susceptibility. In the present experiment, three groups of cats were exposed to 50 impulses produced by a primer explosion (spectral peak at 4 kHz) at peak levels of 135, 140, or 145 dB. Auditory thresholds were electrophysiologically measured from the vertex to 2-, 4-, 8-, and 16-kHz tone pips and losses were determined 30 min after exposure and more than 2 months post-exposure. Losses were greatest at 4 kHz, began to develop at 134-dB peak pressure, and the immediate losses grew at a rate of about 7 dB for every dB increase in peak pressure. About half of the loss measured immediately became permanent. The energy required to begin producing a permanent threshold shift was only about 0.07 J/m2, far lower than that required with continuous noises at lower sound pressures. The data were interpreted as supporting the original hypothesis of greater susceptibility in the midrange.

Acoustic Stimulation↗

PubMedDate not supplied

A comparison of two response-reinforcement methods in pure-tone testing of the retarded.

The purpose of this study was to determine whether a visual reward method or play audiometry is a better motivator in eliciting the lowest possible pure-tone thresholds from a group of Down's syndrome adults. Thresholds were obtained at 250, 500, 2000, 4000, and 6000 Hz for both procedures using a modified ascending method. The method of testing was constructed such that each of the two procedures served as a comparison for validity of the other. The level of significant difference between the play audiometry and the visual reward method was determined using the Sign Test. In each case, there appeared to be a significant difference between the two tests, but the difference was attributed to the order of administration of the tests and practice rather than by the tests themselves. The data obtained suggests that more accurate auditory thresholds may be determined by administering two pure-tone tests and accepting the second as most valid.

Adolescent↗

PubMed2000

Degeneration in the cochlea after noise damage: primary versus secondary events.

PURPOSE: To determine if noise damage in the organ of Corti is different in the low- and high-frequency regions of the cochlea. MATERIALS AND METHODS: Chinchillas were exposed for 2 to 432 days to a 0.5 (low-frequency) or 4 kHz (high-frequency) octave band of noise at 47 to 95 dB sound pressure level. Auditory thresholds were determined before, during, and after the noise exposure. The cochleas were examined microscopically as plastic-embedded flat preparations. Missing cells were counted, and the sequence of degeneration was determined as a function of recovery time (0-30 days). RESULTS: With high-frequency noise, primary damage began as small focal losses of outer hair cells in the 4-8 kHz region. With continued exposure, damage progressed to involve loss of an entire segment of the organ of Corti, along with adjacent myelinated nerve fibers. Much of the latter loss is secondary to the intermixing of cochlear fluids through the damaged reticular lamina. With low-frequency noise, primary damage appeared as outer hair cell loss scattered over a broad area in the apex. With continued exposure, additional apical outer hair cells degenerated, while supporting cells, inner hair cells, and nerve fibers remained intact. Continued exposure to low-frequency noise also resulted in focal lesions in the basal cochlea that were indistinguishable from those resulting from exposure to high-frequency noise. CONCLUSIONS: The patterns of cochlear damage and their relation to functional measures of hearing in noise-exposed chinchillas are similar to those seen in noise-exposed humans. Thus, the chinchilla is an excellent model for studying noise effects, with the long-term goal of identifying ways to limit noise-induced hearing loss in humans.

Animals↗

PubMed1993

Disruption of human eyeblink conditioning after central cholinergic blockade with scopolamine.

Human (Homo sapiens) volunteers (N = 72) received saline, a low dose of oral scopolamine (0.6 mg), a high dose of oral scopolamine (1.2 mg), or a peripheral analogue (glycopyrrolate). They then underwent classical conditioning of the eyeblink response to a tone conditioned stimulus (CS) and a corneal airpuff unconditioned stimulus (UCS) in a delay conditioning paradigm. There was a dose-related decline in acquisition of the conditioned response. These drug-induced conditioning deficits were similar to those previously reported in rabbit eyeblink conditioning and could not be attributed to such nonassociative factors as changes in auditory thresholds to the tone CS, magnitude of reflexive blinks to the airpuff UCS, or to changes in spontaneous blink rates.

Administration, Oral↗

PubMed2005

Effect of audiometric configuration on threshold and suprathreshold auditory steady-state responses.

OBJECTIVE: The purpose of this study was to examine the correlation between auditory steady-state response (ASSR) thresholds and behavioral thresholds in hearing-impaired adults with two common audiometric configurations. A second goal was to compare suprathreshold ASSR growth functions in these two subject groups and to determine whether these growth functions could be used clinically to improve threshold estimation. DESIGN: Thirty adults participated, including 10 subjects with normal hearing, 10 subjects with flat moderately severe sensorineural hearing loss, and 10 subjects with sloping high-frequency sensorineural hearing loss. The accuracy of ASSR threshold estimations for the frequencies of 500, 1000, 2000, and 4000 Hz was compared across groups. In addition, ASSRs were recorded at multiple suprathreshold intensity levels, and the growth of the response was compared across subject groups. RESULTS: ASSR and behavioral thresholds were strongly correlated across all subjects, with no significant difference by audiometric configuration. Slightly poorer correlations were obtained in the normal-hearing subjects than in hearing-impaired subjects and for the 500-Hz test frequency compared with the higher stimulus frequencies. Subtraction and regression methods for predicting behavioral thresholds from ASSR thresholds were equally accurate. Suprathreshold amplitude growth was variable among individuals, but mean growth functions showed steeper slopes in hearing-impaired subjects than in normal-hearing subjects, particularly for the higher frequencies (2000 to 4000 Hz). However, there was not a significant difference in the slopes of amplitude growth functions between subjects with sloping versus flat audiometric configurations for these frequencies, and estimation of threshold from suprathreshold ASSR amplitude growth functions was not advantageous. CONCLUSIONS: ASSR thresholds accurately predicted behavioral threshold equally well for flat or sloping audiometric configurations. The accuracy of threshold estimation for either audiometric configuration and the similar growth function slopes may suggest that there is little spread of activation to neighboring regions of the cochlea when using multiple 100% AM stimuli in subjects with moderately sloping losses. The small amplitude of the ASSR response and individual variability may make threshold estimation based on extrapolation from suprathreshold ASSR responses impractical.

Acoustic Stimulation↗

PubMedDate not supplied

Evaluation of the auditory system: an update.

The purpose of this paper is to describe the audiologic techniques currently used at the Otologic Medical Group, Inc. Auditory threshold in children is determined by a combination of behavioral and objective audiometric techniques. When behavioral techniques fail, auditory brainstem response audiometry combined with impedance audiometry gives a good estimate of hearing thresholds. Impedance audiometry is a valuable addition to the diagnosis of cochlear otosclerosis. This technique is also of benefit in the neurotologic evaluation. Auditory brainstem response audiometry is the most accurate method of detecting an acoustic tumor. We no longer use SISI, tone decay, or Bekesy tests. The newer audiometric studies have greatly improved our evaluation of the auditory system.

Acoustic Impedance Tests↗