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PubMed1993

Classification of audiograms by sequential testing: reliability and validity of an automated behavioral hearing screening algorithm.

In 1990, CAST (classification of audiograms by sequential testing) was proposed and developed as an automated, innovative approach to screening infant hearing using a modified Bayesian method. The method generated a four-frequency audiogram in a minimal number of test trials using VRA (visual reinforcement audiometry) techniques. Computer simulations were used to explore the properties (efficiency and accuracy) of the paradigm. The current work is designed to further test the utility of the paradigm with human infants and young children. Accordingly, infants and children between 6 months and 2 years of age were screened for hearing loss. The algorithm's efficacy was studied with respect to validity and reliability. Validity was evaluated by comparing CAST results with tympanometric data and outcomes of staircase-based testing. Test-retest reliability was also assessed. Results indicate that CAST is a valid, efficient, reliable, and potentially cost-effective screening method.

Acoustic Impedance Tests↗
PubMed1996

Tolerance to sound intensity of binaural coincidence detection in the nucleus laminaris of the owl.

Neurons of the owl's nucleus laminaris serve as coincidence detectors for measurement of interaural time difference. The discharge rate of nucleus laminaris neurons for both monaural and binaural stimulation increased with sound intensity until they reached an asymptote. Intense sounds affected neither the ratio between binaural and monaural responses nor the interaural time difference for which nucleus laminaris neurons were selective. Theoretical analysis showed that high afferent discharge rates cause coincidence detectors with only excitatory input to lose their selectivity for interaural time difference when coincidence of impulses from the same side becomes as likely as that of impulses from the two sides. We hypothesize that inhibitory input whose strength increases with sound intensity protects nucleus laminaris neurons from losing their sensitivity to interaural time difference with intense sounds.

Acoustic Stimulation↗
PubMed1996

[Assessment of cochlear function with distortion products of otoacoustic emissions in acoustic neuroma].

Unilateral hearing loss (HL) caused by an acoustic neuroma (AN) is regarded to be neural ("non-cochlear"). By using otoacoustic emissions it is possible to prove concurrent sensory (cochlear) HL. We prefer distortion-product otoacoustic emissions (DPOAE) because these are more frequency-specific and stable. From April 1994 to May 1996, we examined preoperatively 24 patients with radiologically proven AN. Pure-tone audiometry, DP-grams, brainstem-evoked response audiometry (BERA) and vestibular studies were performed in all cases, while special auditory tests (Fowler, Carhart) and short increment sensitivity indices were also performed in 12 cases. BERA was pathological in 23 cases and latencies were borderline in one case. After comparing audiograms and DP-grams we found 13 patients with sensory HL, 4 patients with combined sensorineural HL and 7 patients with neural HL. There was a strong correlation between the results of DPOAE and the results of special auditory test (phi = 0.63) whereas there was no correlation between tumor size and cochlear function. The result showed that the typical HL caused by AN was a combined sensorineural loss. DPOAE were not suited for the detection of AN but were able to give exact information about any remaining cochlear function.

Adult↗
PubMed1992

Acute ethanol effects on sensory/motor function in baboons with a history of chronic ethanol ingestion.

Baboons with a history of chronic, daily ethanol ingestion were subsequently studied under conditions that assessed the effects of acute oral self-administration of ethanol on auditory and visual threshold functions and reaction times. During the post-chronic experiment reported herein, the animals consumed specific amounts of ethanol twice weekly (0.1, 0.32, 1.0 or 1.3 g/kg), following which they immediately performed psychophysical tests designed to assess ethanol's effects on sensory thresholds and reaction times. Clear, dose-related increases in reaction times were observed following ethanol doses greater than 0.32 g/kg. Trends within individual threshold functions were consistent with systematic changes in auditory and visual threshold sensitivities of 1-3 dB at the high ethanol doses. Reaction time increases ranged from 25 to 180 ms above baseline levels at the highest dose (a 15% average increase). These general findings however, were in contrast to data obtained in the same animals under conditions of daily, chronic ethanol administration which characteristically showed greater sensory/motor effects of up to twice the magnitude of those observed with single doses.

Alcohol Drinking↗
PubMed1980

[Problems of a frequency-specific threshold measurement with the brainstem potentials using the otometric sound pressure signal (damped wavetrain) (author's transl)].

This study aimes at investigating if the damped wavetrain stimulus (Victoreen) may be used in the evaluation of frequency specific thresholds using brainstem potentials. Stimulus frequencies were 1, 4, and 8 kHz. Starting with a control group (10 persons) latency curves for the brainstem potentials were established. The test group included patients with various forms of sensorineural hearing loss in the audiogram. Threshold measurements at the three stimulus frequencies were done with these patients using the potential IV (Jewet V). The latency curves of the normal hearing control group reveal a frequency-specific information being present in the brainstem potentials. This can be derived from latency shifts at different stimulus frequencies. However, investigating patients with a steep slope or a notch in the pure-tone audiogram introduces some difficulties in the ERA-threshold evaluation.

Audiometry, Evoked Response↗
PubMed2001

Electrocochleogram after transection of vestibulo-cochlear nerve in a patient with a large acoustic neurinoma.

This study reports pre- and post-operative compound action potentials (CAPs) that were recorded from a 27-year-old woman with an acoustic neurinoma. During surgery it was necessary to totally sever her vestibulo-cochlear nerve to excise a large tumor. A pure tone audiogram changed to the scale-out pattern immediately after operation. However, CAP, the waveform of which was broadened, has been recorded 3 years post-operatively with a threshold elevation of 10 dB over the pre-operative threshold. This phenomenon suggests that CAP may originate from the extreme periphery of the auditory nerve within the cochlea. The broadening of the CAP was assumed to result from enhancement of the negative summating potential included in the CAP. We studied the effect of preceding stimulus on CAP using paired click stimuli pre- and post-operatively. A reduction of CAP amplitude in response to the second click of paired clicks was markedly suppressed in the inter-click interval between 3 and 80 ms post-operatively. We speculate that depletion of adaptation induced the abnormal CAP recovery described above and that the lateral efferent nerve system was involved in abnormal CAP adaptation with transection of the vestibulo-cochlear nerve in this case.

Action Potentials↗
PubMed1984

Multichannel infant reflex audiometry (MIRA) a new method for evaluating hearing in infants (preliminary results).

Multichannel infant reflex audiometry, applicable up to about 1 year of age, is based on the simultaneous registration of sucking and breathing activities and of eye movements together with marks which indicate the side, beginning, and end of the stimulus. Sucking and breathing are reduced or altered by suprathreshold stimuli. The threshold of responses is 20-40 dB lower than that obtained with behavioral tests and comparable in most cases with BERA thresholds.

Audiometry↗
PubMed2002

[Decision processes at threshold levels during psychoacoustic testing].

Psychoacoustic threshold detection measurements are widely used in clinical and research applications. Usually, a threshold is considered as that intensity of the signal above which the stimulus is detected by the patient and below it will be not. However, this definition is unsatisfactory since there is no such well defined amount of intensity above which the signal suddenly becomes detectable. Rather at intensities close to the "threshold" the patient will be more or less sure to have heard the signal. The more the intensity is increased the more the patient becomes convinced. This paper aims at providing insight into some basics about signal detection close to threshold especially psychometric functions and signal detection theory. It is shown that threshold detection for a given subject not only depends on signal parameters, the subject's co-operation, and on competence of the examiner but also to a great extent on the procedure chosen for estimating the threshold.

Audiometry, Pure-Tone↗
PubMed1985

Relations among some psychoacoustic parameters in normal and cochlearly impaired listeners.

Frequency resolution (viz., masking by low-pass-filtered noise and broadband noise) and temporal resolution (viz., masking by interrupted noise) were compared with hearing thresholds and acoustic reflex thresholds for four normally hearing and 13 cochlearly impaired subjects. Two models, one for frequency resolution (model I) and one for temporal resolution (model II), were introduced, and these provided a means of predicting individual frequency and temporal resolution from hearing thresholds for both normal-hearing and hearing-impaired listeners. Model I is based on the assumption that the upward spread of masking increases in cochlearly impaired hearing with an amount proportional to the hearing threshold in dB HL. Model II is based on the assumption that the poststimulatory masked thresholds return to the level of the hearing threshold within a duration of 200 ms, independent of the level of the masker and the amount of cochlear hearing loss. Model parameters were determined from results from other studies. Although some discrepancies between measured and predicted values were observed, the model predictions generally agree with measurements. Thus, to a first-order approximation, it seems possible to predict individual frequency and temporal resolution of cochlearly hearing-impaired listeners solely on the basis of their hearing thresholds.

Acoustic Stimulation↗
PubMed1995

Lateralization of comodulated complex waveforms.

This study examines the ability to lateralize a complex signal characterized by correlated temporal activity across widely separated frequency regions. The high-frequency complex consisted of two narrow-band stimuli. The two stimuli had common interaural delays but different carriers centered on nonoverlapping critical bands. Two basic conditions were examined: The narrow-band stimuli had temporal envelopes which were (1) identical or (2) different. In the first experiment, narrow bands of noise were used which either had identical temporal envelopes (comodulated) or statistically independent envelopes (CFs = 2550 and 3350 Hz). In the second experiment, two sinusoidally amplitude-modulated (SAM) tones were used whose modulators either had the same starting phase or a different starting phase (CFs = 2550 and 4000 Hz). Results of the first experiment showed that for bandwidths narrower than 300 Hz, comodulated bands produced significantly lower interaural-delay thresholds compared to independent bands. Results of the second experiment showed that when the two SAM tones (100-Hz modulation rate) had the same modulator starting phase, interaural-delay thresholds were lowest.

Acoustic Stimulation↗
PubMed1979

[How to seize and rate a social hearing handicap caused by hearing disorders (author's transl)].

A psychological test to size the quantitative social hearing handicap was developed by High and Fairbanks as a normative anemnesis. The splitting of the social hearing handicap index (SHHI) in the components of deafness and selection ability shows the importance of the selection ability for social hearing. Comparing the pure tone audiogramm with the SHHI of 54 patients demonstrates the low correlation of the audiogramm with the SHHI and especially its selection component. Only when the hearing loss is severe the selection component will correspond to the threshold.

Audiometry↗
PubMed1981

A reconsideration of the parameters for evaluating tympanic reconstruction.

Twenty years' experience with tympanoplasty operations incorporating ossicular reconstruction revealed some unexpected improvements in bone conduction thresholds postoperatively. Because there appeared to be a relationship between this occurrence and the degree of air-bone closure, the possibility that bone conduction thresholds were related to the efficiency of the middle ear sound transformer mechanism was investigated. It has been possible to demonstrate that such a relationship does exist. Its extent and the possible underlying mechanisms are discussed. It is concluded that the evaluation of ossiculoplasty results would be more realistic if they were based on a parameter that measures cochlear function with greater accuracy than do preoperative bone conduction thresholds.

Auditory Threshold↗
PubMed2002

Auditory backward masking in normal hearing children.

Backward masking (BM) is an auditory phenomenon in which the threshold of an auditory signal is elevated due to the presence of another signal (masker) that follows it. Models related to central auditory temporal processes, such as the 'temporal window' model, have been suggested to explain this phenomenon. If this assumption is correct then BM thresholds are expected to improve as a function of age. Electrophysiological data suggest that the central auditory system undergoes maturation in the first two decades of life. Empirical data on the development of BM with age are limited. Therefore, the goals of the present study were to study the effect of age on the performance of backward masking in normal developing children and to determine the age at which children reach adult-like performance. Subjects were 30 normal developing children divided into three groups according to age: 7, 9 and 11 years old. Stimuli consisted of a 1000 Hz pure tone and a bandpass masker (600-1400 Hz). Three BM threshold estimates were obtained for each subject using a three-alternative forced-choice adaptive procedure. The data show a trend for improvement in backward-masking thresholds with increasing age. Specifically, 7 and 9 year-old children performed significantly poorer than those reported for adults, whereas 11 year-old children reached adult-like performance. These data contribute to the small body of literature on backward masking in normal developing children. They are in keeping with what is known regarding the age of physiological maturation of the auditory system and have important clinical implications in the assessment of children with suspected temporal processing deficits.

Acoustic Stimulation↗
PubMed1984

Fusion of stereocilia on inner hair cells in man and in the rabbit, rat and guinea pig.

The complexity of the problem of sensorineural hearing loss is illustrated by the well-known poor correlation between pure tone thresholds and loss of sensory cells in the organ of Corti and between pure tone thresholds and other auditory functions such as discrimination of speech and thresholds of the intra-aural muscle reflex (MER). The present work demonstrates that two types of inner ear pathology are present in several mammalian species, including man. Both types can be induced by noise. In addition to the earlier well-known loss of outer hair cells, it is shown that abnormal sensory hairs on inner hair cells are an important and frequent finding in acoustically damaged ears. Fusion and inclination of inner hair cell cilia were predominant in rabbits with moderate hearing loss and a rather common finding in rats and humans. In guinea pigs, damage to inner hair cell stereocilia was not common and was seen only in conjunction with considerable loss of outer hair cells. In summary, fusion of the stereocilia of inner hair cells was a common finding in several mammalian species.

Adult↗
PubMed1997

Cytoarchitecture and sound activated responses in the auditory cortex of the big brown bat, Eptesicus fuscus.

Under free field and closed-system stimulation conditions, we studied the frequency threshold curves, auditory spatial sensitivity and binaurality of neurons in the primary auditory cortex (AC) of the big brown bat, Eptesicus fuscus. All 298 recorded AC neurons discharged phasically. They were recorded at depths less than 1,000 microns with response latencies of 7-25 ms, best frequencies (BFs) of 28-97 kHz and minimum thresholds (MTs) of 8-90 dB SPL. They received excitatory inputs from the contralateral ear and either excitatory (EE) or inhibitory (EI) inputs from the ipsilateral ear. These cortical neurons were tonotopically organized along the anteroposterior axis of the AC. High best frequency neurons were located anteriorly and low best frequency neurons posteriorly. They were most sensitive to sounds delivered from a restricted region of the contralateral frontal auditory space (0 degree-50 degrees in azimuth and 2 degrees up, 15 degrees down in elevation). Frontal auditory space representation appears to be systematically arranged according to the tonotopic axis such that the lateral space is represented posteriorly and the middle space anteriorly. Cortical neurons sequentially isolated from an orthogonally penetrated electrode had similar frequency threshold curves, BFs, MTs, points of maximal auditory spatial sensitivity and binaurality. The EE and EI columns are organized concentrically such that the small number of centrally located EE columns were surrounded by an overwhelming number of EI columns. Using Nissl and Golgi stains as well as c-fos immunocytochemistry, we studied the cytoarchitecture, cell types and sound elicited Fos-like immunoreactivity in the primary AC of this bat species. The primary AC of this bat species can be described into molecular (137 microns), external granular (55 microns), external pyramidal (95 microns), internal granular (102 microns), internal pyramidal (191 microns) and multiform (120 microns) layers. The main type of cells distributed among these six layers are the small, medium and large pyramidal cells. Others include the stellate, horizontal, granular, fusiform, basket, and Martinotii cells. When stimulated with 30 kHz and 79 dB SPL sounds under natural conditions, bilaterally and symmetrically distributed Fos-like immunoreactive neurons were observed in about 20% of neurons in each AC. When stimulated under monaurally plugged conditions, 39-48% more of Fos-like immunoreactive neurons were observed in the ipsilateral AC. This finding supports the fact that the primary AC receives auditory inputs mainly from the contralateral ear.

Acoustic Stimulation↗
PubMed1989

The 40-Hz potential and SN10 as measures of low-frequency thresholds.

This study investigated the accuracy of threshold estimates using the 40-Hz Potential and the SN10 in the presence of elevated low-frequency thresholds. In Experiment 1, subjects with normal hearing were evaluated with ipsilateral low-pass masking to elevate low-frequency thresholds and in Experiment 2, subjects with low-frequency sensory hearing losses were evaluated. The stimuli were 500-, 1500-, and 3,000-Hz tone pips. The 40-Hz Potential and the SN10 were equally good predictors of the behavioral threshold when the low-frequency, pure-tone thresholds were elevated.

Adult↗