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PubMed1996

Replication of a P50 auditory gating deficit in Australian patients with schizophrenia.

Schizophrenic patients reportedly have a deficit in the control of sensitivity to auditory stimuli as shown by the P50 auditory evoked potential wave in a conditioning-testing paradigm that measures suppression of response to a repeated stimulus. Although this finding has been replicated by several US laboratories, one European group has not found differences between schizophrenic patients and normal control subjects. In the present study, investigators in the Schizophrenia Research Center at the Prince of Wales Hospital in Sydney, Australia, selected 22 normal control subjects, 11 acutely ill schizophrenic inpatients, and 11 clinically stable schizophrenic outpatients. Both schizophrenic groups were treated with similar doses of classical neuroleptic medications. Evoked potentials were recorded by an investigator from the US laboratory that initially reported the difference; five averages, each the response to 32 stimulus pairs, were recorded from each subject. The normal control subjects demonstrated significantly more suppression of the P50 response to the repeated stimuli than the schizophrenic groups, as previously reported. There were no significant changes in the suppression measure over the five trials. The suppression of the P50 wave by schizophrenic outpatients was somewhat greater than that by schizophrenic inpatients, but both schizophrenic groups had decreased suppression, compared with the normal subjects. The mean P50 suppression for five averages was successfully used in a logistic regression to classify subjects as normal or schizophrenic. This method was more accurate than attempts to classify subjects with only one average. The mean amplitude of the initial conditioning response did not differ between groups. Schizophrenic patients had slightly shorter mean latencies. There was no direct relationship of P50 suppression to measures of clinical psychopathology.

Adult↗
PubMed2005

The effect of speaking task on perceptual judgment of the severity of dysphonic voice.

This study investigated the effect of speaking task on auditory-perceptual judgment of the severity of dysphonia. Three speech-language pathologists experienced in evaluating of disordered voices rated 29 recorded speakers, each of whom produced speech elicited via the same three tasks: sustained vowel /a/, oral reading of a standard passage, and connected speech describing a standard picture. Stimuli were played in sound field, and raters used direct magnitude estimation with a visual analog scale. A repeated measures analysis of variance (ANOVA) revealed a statistically significant (P < .05) effect of speaking task, with post hoc analyses that indicate a statistically significant difference between ratings for the sustained vowel versus connected speech elicited via picture description (P < .05). No statistically significant difference in ratings was found between oral reading and picture description or between oral reading and the sustained vowel. The ANOVA also revealed a statistically significant difference among raters (P < 0.001), but no statistically significant task by rater interaction. Possible reasons for an effect of speaking task are discussed. Also, the implications of one task for determination of dysphonic severity are discussed, as is the possibility of a task effect when determining other clinically useful vocal parameters.

Adult↗
PubMed1978

A study of the central auditory processes in stutterers using the Synthetic Sentence Identification (SSI) Test battery.

The performance of a group of stutters (N = 14) and a group of nonstutterers (N = 14) was compared on the Synthetic Sentence Identification Test (Speaks and Jerger, 1965). The test is designed to assess central auditory function. It was hypothesized that because of subtle neurologically based differences in perceptual processing, the performance of the two groups would differ significantly on one or more of the subtests. An analysis of variance revealed that the performance of the stuttering group was significantly poorer (0.01 level of confidence) than that of the nonstutteres on the Ipsilateral Competing Message Subtest. The results of the investigation were compatible with other studies that suggest a neurological dysfunction within the central auditory apparatus as at least one of the underlying causes of disfluency. It was concluded that further investigations of the central auditory processes in stutterers are warranted to make a more definitive statement about the etiology of stuttering.

Adolescent↗
PubMed1989

Auditory time constants for off-frequency forward masking in normal-hearing and hearing-impaired listeners.

Previous research has shown that frequency-specific estimates of auditory time constants for recovery from short-term adaptation can be made using a fixed-probe forward-masking procedure (Nelson & Freyman, 1987) if the masker and the probe stimuli are at the same frequency. This study examines the validity of time-constant estimates for off-frequency forward-masking conditions in which the masker frequency is below (900 Hz) or above (1100 Hz) the probe frequency (1000 Hz). Fixed-probe-level temporal masking functions were obtained from four normal-hearing and four hearing-impaired listeners. Auditory time constants were estimated with iterative least-squares procedures to derive parameter values for an exponential model of recovery from forward masking. After appropriate corrections were made for attenuation to the maskers provided by the auditory filter centered at the probe frequency, recovery from forward masking produced by either off-frequency or on-frequency maskers could be described by a single time constant. That time constant was around 50 ms in normal-hearing listeners and was larger in those hearing-impaired listeners who demonstrated moderate hearing loss at the probe frequency.

Auditory Fatigue↗
PubMed1999

Auditory temporal processing impairment: neither necessary nor sufficient for causing language impairment in children.

Fourteen twin pairs, aged 8 to 10 years, were tested 3 times over 12 months; they included 11 children with language impairment (LI), 11 control children matched on nonverbal ability and age, and 6 co-twins who did not meet criteria for LI or control status. Thresholds were estimated for detecting a brief backward-masked tone (BM), detection of frequency modulation (FM), and pitch discrimination using temporal cues (deltaf0). Both BM and FM thresholds improved with training, and by the 2nd test session, FM thresholds were in the adult range. There were marked individual differences on BM and deltaf0 and, for both tasks, performance correlated with Tallal's Auditory Repetition Task administered 2 years previously. However, no auditory measure gave significant differences between LI and control groups; performance was influenced more by nonverbal than language ability. Some children did have a stable pattern of poor performance on certain auditory tasks, but their good FM detection raised questions about whether processing of auditory temporal information is abnormal. We found no evidence that auditory deficits are a necessary or sufficient cause of language impairments.

Adult↗
PubMed1993

Temporal masking of human auditory evoked brain stem responses using two simultaneously presented maximum length sequences.

Two simultaneously presented maximum length sequences (MLSs) were used to investigate temporal nonlinearities. Not only did the recorded auditory evoked brain stem responses to these stimuli predictably increase in latency and decrease in amplitude as a function of the temporal interactions between MLSs, but thresholds were elevated by more than 20 dB. Simultaneous MLS paradigms make it possible to investigate a number of nonlinearities in the auditory system efficiently. This study also demonstrated that binaural MLS techniques can be used to assess auditory function even in individuals with asymmetric hearing losses without fear of crossover effects.

Acoustic Stimulation↗
PubMed1993

Auditory filter shapes in normal-hearing, noise-masked normal, and elderly listeners.

To dissociate the effects of age and hearing impairment on changes in frequency selectivity, auditory filter shapes were measured at 2 kHz in four groups of subjects: (1) normal-hearing young subjects; (2) normal-hearing elderly subjects; (3) elderly hearing-impaired listeners; and (4) young normal-hearing listeners with simulated hearing losses. Filter shapes were derived using a modified version of the notched-noise procedure [Glasberg and Moore, Hear, Res. 47, 103-138 (1990)]. Equivalent rectangular bandwidths (ERBs) of auditory filters were not significantly different in young and elderly subjects with normal 2-kHz hearing. Furthermore, filter widths for young subjects with 20- and 40-dB simulated hearing losses overlapped with those obtained from elderly subjects with corresponding degrees of actual hearing loss. One measure that did show significant differences between actual and simulated hearing losses was the degree of filter asymmetry; auditory filters in hearing-impaired listeners were more asymmetrical than those obtained from noise-masked normal-hearing subjects. The dynamic range of auditory filters, however, was comparable for hearing-impaired and noise-masked listeners. Lastly, post-filter detection efficiency was also similar for young and elderly subjects with equivalent hearing levels. These findings suggest that the reduced frequency selectivity often reported for older listeners can be attributed, primarily, to hearing loss rather than increased age. Implications of the results for speech perception in the elderly and models of hearing impairment are discussed.

Acoustic Stimulation↗
PubMed1995

The phenomenology of perceptual hallucinations in alcohol-induced delirium tremens.

In a qualified detoxication, states of anxiety caused by hallucinations can be specifically assimilated and psychologically reduced. Knowledge of the hallucinations experienced promotes the subsequent motivation phase. A semistandardized investigation of 64 patients with alcohol-induced delirium tremens was carried out over a period of 14 months in order to establish the nature of their perceptual hallucinations. Visual hallucinations predominated followed by auditory and tactile perceptual hallucinations. Amongst visual hallucinations pertaining to animals, the well-known 'white mice' were only reported once. Hallucinated cats, dogs, and snakes were most frequent, and were only then followed by mice (in general).

Adult↗
PubMed1996

Auditory temporal resolution in specifically language-impaired and age-matched children.

Recently there has been renewed interest in the auditory processing capabilities of children with specific language impairment. In this study, eight children with specific language impairment and eight nonimpaired, age-matched peers completed a task to assess temporal resolution abilities. Children were asked to detect a tone in three masking conditions wherein the masker contained silent gaps of 0 msec., 40 msec., or 64 msec. in duration. Thresholds were measured in each masking condition at 500 Hz and 2000 Hz. Across the groups, thresholds decreased (improved) significantly as a function of increases in the duration of the gaps. Children in the two groups exhibited remarkably similar thresholds for the three masking conditions. However, children with specific language impairment required a significantly greater number of ascending trials to achieve the threshold criterion than did age-matched children. Results suggest that language-impaired children perceive temporal aspects of acoustic stimuli as well as their normally developing peers. Attentional mechanisms may play an important role in the difficulties they exhibit in auditory processing.

Attention↗
PubMedDate not supplied

Cross-modal matching of loudness and brightness as a recruitment test for hearing-impaired children.

Normal 5-year-olds have been reported to be able, in a simple game situation, to match brightness to loudness in the same way as a control group of adults. This study investigated supplanting the normal ear in an alternate binaural loudness balance test (ABLB) with the visual modality, as a recruitment test designed especially for bilaterally hearing-impaired children. The results of normal 10-year-olds, with simulated hearing losses, suggest that category scaling was adopted naturally as a simplifying strategy in preference to ratio scaling (absolute judgements). No proportional increase in the matching function slope was evident, despite the amount of recruitment measured with an ABLB. The instructions needed to combat this strategy render the test unfeasible with hearing-impaired children.

Acoustic Stimulation↗
PubMed1990

The temporal resolution factor with and without background noise.

In this paper we discuss the measurement of the temporal resolution factor (TRF). The major merits of this measurement are that it is simple enough to be used clinically and that the results are, within certain limits, independent of presentation level. Addition of a continuous background noise has been suggested to enhance the discriminative power of TRF between normal-hearing listeners and listeners with poor temporal resolution. However, we showed through a simple model that this background noise may introduce a strong dependence on presentation level, which must be taken into consideration. To test our model we developed a new measurement protocol. This protocol was applied in measurements of 5 normal-hearing and 9 sensorineurally hearing-impaired listeners. Their results could reasonably well be fitted by the model. The model predicts large measurement errors for TRF values determined with background noise. We found the standard deviations of TRF values, calculated from test and retest measurements, to be smaller in conditions without a continuous background noise. In addition, our results did not show the predicted enhancement in discriminative power between normal-hearing and hearing-impaired listeners. Therefore, the primary conclusion is that the determination of the TRF is not improved by adding a background noise.

Adaptation, Physiological↗
PubMed1977

The frequency selectivity of the 500 HZ frequency following response.

In order to evaluate the frequency selectivity of the 500 Hz FFR we applied narrow-band masking at closely spaced center frequencies in the range 0.25 to 4 kHZ. The results show clearly that it is the apical part of the cochlea that generates the 500 Hz FFR, but the area of the basilar membrane that contributes is rather broad. It was evident that some of the masking effect that was observed in the Vertex-derived response stemmed from as yet obsure brain stem mechanisms. Examination of 3 patients with selected types of hearing impairment confirmed the masking results. When there is a low frequency loss there will still be a 500 Hz FFR and the same is true when the loss is in the medium to high frequencies. It is possible that precise determination of the latency to single waves in the response may allow a more exact prediction with regard to which location on the basilar membrane generates the response in the individual patient.

Acoustic Stimulation↗
PubMed1996

Auditory performance and acoustic reflexes in young adults reporting listening difficulties.

We aimed to determine whether reported difficulties in speech understanding are associated with abnormal acoustic reflex thresholds (ARTs). The acoustic reflex has been shown to have a role in the understanding of speech at high intensities by ensuring that the strong low-frequency components of sound do not excessively mask the higher-frequency components, which are important for speech understanding. There is also wide variance in individual ARTs. Hence, the possibility arises that subjects reporting listening difficulties in noise have abnormal acoustic reflex function. In this investigation, a questionnaire to 2395 university students was used to obtain 20 subjects reporting listening difficulties in background noise and requesting advice about their hearing problems; it also screened out significant histories of middle ear disease in childhood. These subjects, and 20 control subjects reporting no listening difficulties, received a battery of performance tests and measures of acoustic reflex thresholds. Results showed significant differences in auditory performance between subjects reporting listening difficulties and those with no such difficulties, but no differences in acoustic reflex thresholds. These findings extend the relationship between reported listening difficulties and auditory performance within the "normal hearing' range, but this relationship is unlikely to be due to abnormal acoustic reflex thresholds.

Auditory Threshold↗
PubMed1999

Auditory temporal and spectral resolution in normal and impaired hearing.

Temporal, spectral, and combined temporal-spectral resolution of hearing was assessed by recording masked hearing thresholds. The masker was an octave band noise. Spectral resolution was assessed by introducing a spectral gap of half an octave bandwidth in the masker. A 50-msec gap assessed temporal resolution. The spectral and temporal gaps were used separately or simultaneously. Normal-hearing and hearing-impaired subjects participated. For each masking condition, the subjects were tested at masker levels 50, 60, 70, and 80 dB SPL and at test-tone frequencies 0.5, 1, 2, and 4 kHz. Normal-hearing subjects showed reduced masking with spectral and temporal gaps. The combination of spectral and temporal gap reduced masking further. The release of masking was dependent upon the masker level. Hearing-impaired subjects showed less release of masking than normal-hearing subjects. The degree of hearing impairment was inversely related to release of masking. Reliability of the test procedure was assessed.

Adolescent↗