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Biomedical subjects

F Schwetz

Publications and source records attributed to F Schwetz.

At least 19 recordsLinked to original sources
PubMed1992

Hearing loss from industrial noise, head injury and ear disease. A multivariate analysis on audiometric examinations of 110,647 workers.

From compulsory screening examinations of 260,917 noise-exposed workers standardized audiograms as well as medical and occupational histories of 110,647 workers were selected because of full-time exposure to well-defined noise greater than 85 dB (A) and analyzed by loglinear and multiple linear regression. The most important factors for prediction of pure-tone hearing loss at 4 kHz were found to be age, sex and noise immission level. For predicting speech impairment and handicap the history of ear disease, head injury and tinnitus were more important than noise immission level. Dose-response relationships are given to improve prevention and compensation of hearing loss from combined factors.

Adolescent↗
PubMed1992

[Impact noise and hearing. A study from audiometry screening in noisy occupational environments].

The hearing loss of 46,776 subjects exposed to hazardous impact or continuous noise was measured: 11% were exposed to impact noise (10.3% in men, 12.7% in women). Impact noise causes less hearing loss than continuous noise up to a noise emission level (NIL) of 115 dB(A). This result is still compatible with the concept of equivalent continuous A-weighted sound pressure level (LA,eq) and seems to be caused by the protective effect of the stapedius muscle. However, at emission levels higher than 115 dB(A), not covered by ISO 1999 prognosis, impact noise becomes more detrimental. This could be the effect of mechanical damage to the organ of Corti, as observed in animal experiments at sound pressure levels exceeding 114 dB(A). A diminishing protective function of the stapedius muscle could explain the more serious hearing impairment after long exposure to impact noise compared with shorter exposures to an equal dose. Since the hearing loss caused by impact or continuous noise is clearly different in the highest NIL ranges, safety criteria for impact noise should be revised. The NIL defined by Burns and Robinson underestimates the effect of the exposure time for impact noise.

Adolescent↗
PubMed1991

Risk factors for hearing loss at different frequencies in a population of 47,388 noise-exposed workers.

Weighted regression analysis was applied to determine the dependence of the hearing thresholds of 47,388 noise-exposed workers on age, sex, noise immission level, ear disease, head injury, tinnitus, hearing protector usage, and audiometric frequency in the range from 0.5 to 6 kHz. It could be shown that the hearing thresholds at any frequency are dominated by the age of the worker and that women, after equivalent exposure conditions, hear better than men. The relative effects of sex, noise immission level, ear diseases, tinnitus, and hearing protector usage are related to the audiometric frequency. Users of hearing protectors at the last audiometric investigation hear worse than nonusers. Hearing protector usage is strongly related with the hearing threshold in the low-frequency range. The noise immission level does not noticeably affect the hearing threshold below 3 kHz. The most important frequency of the noise immission level is as expected 4 kHz. For 4 kHz, it was shown that the variables age, noise immission level, tinnitus, head injuries, and ear diseases act in a good approximation additively on the pure-tone hearing threshold.

Adolescent↗
PubMed1987

[Auditory adaptation and auditory fatigue].

Twenty subjects without otological disease were examined for auditory thresholds by Békésy audiometry and by the Feldmann Test (Adaptogramm), before and after noise exposure to one ear of 90 db SPL at 3 kHz for 15 minutes. The exposed ear was also tested for hearing fatigue (TTS). There was no significant correlation between Békésy audiometry and Feldmann test curves or between these adaptation tests and the hearing fatigue test (TTS) after noise exposure. Our results suggest that these methods of measuring adaptation do not correspond, and that adaptation measurements, prior to noise exposure, have no predictive value for hearing fatigue test results following noise exposure. After noise exposure changes were found in the non-exposed ear which were manifested as variability of the Békésy audiometry curves and flattened Feldmann curves. We thought that these results might indicate a central adaptation following noise exposure. There was interference of this so called "central adaptation" with peripheral fatigue in the exposed ear.

Audiometry, Pure-Tone↗
PubMed1987

[Progression of accident-induced hearing damage].

There are generally accepted opinions on the origin of auditory lesions due to accidents. The views on their possible progression, however, are divergent. One of the reasons is lack of sufficient information. Therefore serial audiological observations of such lesions are required, as are available for workers exposed to noise. In order to exclude the influence of noise on the organ of hearing, only auditory lesions which were strictly unilateral and which lay within a frequency range not susceptible to noise were followed up. The present study investigates the progressive decrease in hearing associated with the type of injury, the pure-tone audiometric pattern and the progress within a given period of time. It is remarkable that our material shows progressive hearing loss only after trauma due to explosion or head injury, and not after blast trauma. Thus it is not acoustic damage to the internal ear, but only mechanical damage which leads to progression. This theory was advanced by Lehnhardt many years ago.

Audiometry, Pure-Tone↗
PubMed1980

[Audiological supervision of workers exposed to noise in Austria (author's transl)].

The recent Worker's Protection Law entails an extension of the local precautions in industries with a high noise level. In order that the necessary duties can be better accomplished the Federal Ministry for Social Administration has appointed "authorized doctors". A large proportion of these colleagues are not ENT specialists. It was therefore necessary to work out guiding principles which permit as exact and uniform an assessment of the worker as possible both at the medical examination on taking up work and at the routine audiometric checks. These guide-lines are discussed in greater detail with reference to practical examples.

Audiometry↗
PubMed1978

[The threshold of 1.5 khz as a graduator for the noise induced hearing defect (author's transl)].

Austria's new legislation on the protection of employees and workers provides that the determination and assessment of noise-induced hearing defects caused at the working places may now also be carried out by physicians who are not otologists. Since language-audiometric data are not available to such physicians, the assessments are based only on sound-audiometric hearing results. Therefore, it is understandable that such physicians would like to be able to draw conclusions as to the extent of the noise-induced hearing defect from the sound-audiogram alone. The difficulties encountered in the attempt to determine language-hearing on the basis of sound-hearing are well-known. Among all defects the noise-induced hearing defect is still best suited for such attempts because of its stereo-typical curve in the sound-audiogram. 500 cases with a pure noise-induced hearing defect are subjected to a multiple regression analysis. The result of the investigation confirms the practical observations made. The sound-audiometric hearing loss at 1.5 kHz is closely related to the discrimination capacity for our language and thus gives some indication as to the degree of the noise-induced hearing defect.

Audiometry↗
PubMed1976

[Operative repair of the traumatically disrupted ossicular chain (author's transl)].

Consequent to the large number of skull injuries following traffic accidents, a significant number of patients experience traumatic disruption of the ossicular chain. Although most of these injuries can be managed by standard otologic procedures, this communication deals with three special clinical problems. Although not previously encountered, the diagnosis in the first could be made by otoscopy. In the second, infracture of the malleolar head had produced injury to the facial nerve which was exposed in its horizontal course. Although transposition of the malleus was required in repair, significant interference with hearing had not occurred since a spontaneous tympanoincudopexy had been produced by the injury.

Adolescent↗