Biomedical subjects

P Corthals

Publications and source records attributed to P Corthals.

5 recordsLinked to original sources

PubMed1998

Masking effects and tinnitus as explanatory variables in hearing disability.

In cases of substantial auditory handicap, the degree of pure-tone hearing loss or hearing loss for speech is seen as the primary determining factor. Sometimes the presence of tinnitus complaints and disproportionate masking effects of noise on speech reception are seen as aggravating factors. To investigate the relevance of tinnitus and masking effects in the context of hearing disability, four factorial designs with self-perceived hearing disability as the dependent variable were submitted to an analysis of variance. Impact of masking and tinnitus complaints were treated as independent variables with two levels and were each combined with a second independent variable to form a 2 x 2 fixed factor statistical model. This second independent variable was either hearing loss for pure tones (first and second model) or speech reception ability (third and fourth model). Both hearing loss for pure tones and speech reception capability were found to be significant explanatory factors for hearing disability. Impact of masking, if juxtaposed to average pure-tone hearing loss (first model), also came out of the analysis as a significant factor in hearing disability, whereas the tinnitus factor did not reach significance levels. No significant interactions between factors were found. The results support the idea of the differentiating audiogram-based disability estimates by taking noise susceptibility into account. The findings also suggest in an equivocal relation of tinnitus with hearing disability, which prevents it from being a straightforward disability predictor.

Aged↗

PubMed1997

Bilateral threshold frequency weighting in hearing disability predictions.

Hearing disability can be measured by questionnaires, interviews or self-ratings. As these measurement techniques are not always appropriate for direct application in individual cases, particularly in the context of compensation claims, the assessment is sometimes reduced to a surrogate measure derived from audiometric thresholds. No final agreement emerges from correlation studies on hearing disability as to the optimal set of audiometric descriptors. However, a multiple regression equation, describing the relationship between audiometric data and numerically expressed self-ratings of disability, provides a means for predicting disability with relatively good precision, using some index derivable from the audiogram. The aim of the present study was to consolidate or amend current prediction schemes based on tonal audiometric data by investigating the problem of differential bilateral weighting of threshold frequency through multiple regression performed on experimental data coming from an unbiased group of hearing impaired subjects. In addition to tonal thresholds, this corpus included simple, quantitative self-ratings for disability. The sample was considered to be a representative cross-section of adult hearing impaired ENT patients. The results indicate that prevailing bilateral weightings are likely to overestimate the importance of the worse ear. The regression results did not incorporate the usual threshold values and frequency weightings. The outcome nevertheless offered a multiple correlation coefficient that was higher than most correlations reported in the literature between disability ratings and threshold values.

Adolescent↗

PubMedDate not supplied

Audiovisual speech reception in noise and self-perceived hearing disability in sensorineural hearing loss.

Multiple regression analyses were performed on a corpus of data from 56 sensorineurally hearing-impaired subjects. In addition to tonal thresholds, the corpus included simple, quantitative self-ratings for disability and results from speech reception tasks in auditory-only, audiovisual, quiet and noisy conditions. The aim was to evaluate to what extent the predictive power of disability formulas based on the audiogram can be enhanced, when measures derived from speech reception tasks are added to tonal thresholds as supplementary predictors. The better-ear speech reception threshold proved to be a strong exclusive predictor: if speech reception thresholds were introduced into the prediction, the contribution of better-ear pure-tone averages became redundant. Speechreading ability always significantly enhanced the prediction's accuracy. Tonal thresholds or speech reception data combined with lipreading ability scores can explain considerable amounts (42 per cent and 54 per cent, respectively) of the variance in disability ratings. The conclusion is that auditory-only, audiogram-based prediction schemes must not be abandoned, but can be tailored to individuals on the basis of realistic audiovisual speech reception performance.

Adult↗

PubMedDate not supplied

Multi-variant analysis of otoacoustic emissions and estimation of hearing thresholds: transient evoked otoacoustic emissions.

Evaluation of cochlear hearing loss by means of transiently evoked otoacoustic emissions is already established in clinical practice. However, accurate prediction of pure-tone thresholds is still questioned and is still regarded as troublesome. Both click- and tone-burst-evoked otoacoustic emissions at several intensity levels were measured and analysed in 157 ears from normally hearing and 432 ears from patients with different degrees of pure sensory hearing loss using the ILO88/92 equipment. Results of otoacoustic emissions (OAE), elicited by clicks and tone-bursts at centre frequencies from 1 to 5 kHz, were analysed using two different statistical methods. Both multivariate discriminant analysis and forward multiple regression analysis were used to determine which OAE variables were most discriminating and best at predicting hearing thresholds. We found that a limited set of variables obtained from both tone-burst and click measurements can accurately predict and categorize hearing loss levels up to a limit of 60 dB HL. We found correct classification scores of pure-tone thresholds between 500 and 4000 Hz up to 100 per cent when using combined click and tone-burst otoacoustic measurements. Prediction of pure-tone thresholds was correct with a maximum estimation error of 10 dB for audiometric octave frequencies between 500 and 4000 Hz. Measurements of multiple tone-bursts OAEs have a significant clinical advantage over the use of clicks alone for clinical applications, and a good classification and prediction of pure-tone thresholds with otoacoustic emissions is possible.

Acoustic Stimulation↗

PubMedDate not supplied

Sensitivity of transient evoked and distortion product otoacoustic emissions to the direct effects of noise on the human cochlea.

Measurement of otoacoustic emissions (OAEs) has been proposed as a sensitive test to reliably assess the effects of noise exposure. The present study in humans was designed to evaluate the sensitivity and applicability of transient evoked OAEs (TEOAEs) and 2f1-f2 distortion product OAEs (DPOAEs) as quantitative indices of the functional integrity of the outer hair cells (OHC) during growth of and recovery from temporary threshold shift (TTS). This was examined in two different groups of volunteers by measuring the per- and post-stimulatory effects of a one hour BBN and an on-site five hour exposure to loud music from a discotheque. The results of both experiments show consistent growth and recovery patterns for both DPOAEs and TEOAEs. For TEOAEs, both the reproducibility scores and signal to noise ratio values for the 4 kHz frequency band exhibited the greatest sensitivity. The DPOAEs, on the other hand, showed the greatest sensitivity between 2 and 5.5 kHz. Thus, both the TEOAEs and DPOAEs have a great potential in the detection of TTS after noise exposure.

Adult↗