Noise deafness
| Classification according to ICD-10 | |
|---|---|
| H83.3 | Noise damage to the inner ear - noise- related hearing loss |
| ICD-10 online (WHO version 2019) | |
Under noise induced hearing loss is defined as a chronic noise exposure resulting (usually at work) sensorineural hearing loss . It is one of the sonic dreams .
Hearing fatigue
If noise of high intensity (> 85 dB A ) affects the ear, it leads to hearing impairment after hours (synonyms: hearing fatigue, temporary threshold shift; English: Temporary Threshold Shift, TTS for short). However, this hearing impairment is reversible and the hearing threshold normalizes again over the course of hours or days . The duration of the recovery time depends on the extent of the TTS.
Noise deafness
Does high-intensity noise (> 85 dB A ) have an effect for a long time, i. H. Over the years several hours a day on the hearing organ, this leads to permanent and irreversible damage to the hearing organ (noise-induced hearing loss).
The place of damage are the hair cells in the organ of Corti of the snail . The decline of the hair cells begins largely independent of the physical characteristics of the damaging noise in the area of the lowest turn of the snail (basal turn), which corresponds to the analysis of about 4000 Hz . From here the process spreads in both directions over time. In the area of the apex there is never a complete destruction of the hair cells, so complete deafness does not arise as a result of chronic noise exposure. Noise-induced hearing loss is very often associated with tinnitus , which is seldom the main symptom.
The development of noise-related hearing loss is dependent
- the duration of the noise exposure,
- of the level and frequency spectrum of the impact noise,
- the presence of any noise pauses during daily exposure and its distribution, and
- of individual factors.
If the sound pressure level is below 85 dB (A), no hearing impairment is to be expected; as the sound pressure level increases, the risk of damage to the hearing organ and the extent of the expected hearing impairment increase. At particularly high sound levels, u. A noticeable hearing impairment can result after just a few years, while with lower exposure it takes decades to develop.
The sensitivity of the hearing organ is much higher for frequencies between about 1000 and 6000 Hz than for lower and higher frequencies.
If there are frequent interruptions (noise breaks) during daily exposure, the ear can recover in each case; in any case, this increases the tolerance of the hearing organ to noise considerably.
Ultimately, the individual sensitivity to noise is not uniform. Only a small proportion of those exposed to noise suffer from hearing impairment to such an extent that speech comprehension is considerably restricted.
The tone audiogram shows symmetrical sensorineural hearing loss (inner ear hearing loss ) in the high frequency range with recruitment . The noise damage first becomes noticeable in the form of a lowering of the hearing threshold curve at around 4000 Hz (“ c5 sink ”), then this sink becomes deeper and wider and then also affects lower and higher frequencies. In extreme cases, the development leads to high frequency deafness, the hearing ability for medium or even low tones is less or not at all impaired.
Years or decades of noise exposure can practically only be found in professional life. Around four to five million employees are exposed to harmful noise in the workplace. Noise deafness is therefore a typical occupational disease (BK no. 2301) and as such is taken into account by law. Workers who are exposed to a noise level of 85 dB (A) daily noise exposure level or more must take part in preventive occupational health care before starting work in the noisy area and have follow-up examinations at regular intervals. 13,546 cases of occupational diseases were recognized in Germany in 2008, of which 5,158 were noise-related hearing loss. In 2014 the number rose to 6,649 recognized cases, in 2018 there were 6,714 recognized cases - noise-related hearing loss is the most common recognized occupational disease in Germany.
The daily noise exposure level (L EX, 8h ) is according to the definition in the Noise and Vibration Occupational Safety and Health Ordinance (LärmVibrationsArbSchV) § 2 (2), the noise exposure level averaged over time based on an eight-hour shift. It includes all sound events occurring in the workplace.
The use of individual hearing protection (ear muffs, preformed or shapeable ear plugs, ear molds = revised hearing protection) is from a day noise exposure level of 85 dB (A) and peak sound pressure level of 137 dB (C) (upper trigger threshold - the noise region) in professional activities mandatory. From a daily noise exposure level of 80 dB (A) or 135 dB (C) peak sound pressure level (lower triggering threshold), the employer must provide hearing protection and offer voluntary occupational health care "noise (G20)".
The use of hearing protection is also strongly recommended in the event of private exposure to noise.
See also
- Boenninghaus syndrome , acute form of noise-related hearing impairment.
literature
- KD Kryter: The Effects of Noise on Man. Academic Press, New York, 1970
- W. Burns: Noise and Man. John Murray, London, 1973
- D. Henderson et al. (Ed.): Effects of Noise on Hearing. Raven Press, New York, 1976
- H.-G. Dieroff: Noise deafness. Gustav Fischer Verlag, Jena, 1994
- RA Dobie: Medical-Legal Evaluation of Hearing Loss. 2nd ed. 2001, Singular, pp. 138ff
- H. Feldmann: The opinion of the ear, nose and throat doctor. G. Thieme Verlag Stuttgart, 6th edition 2006, pp. 176ff
- B. Welleschik : Noise deafness as a probability diagnosis. Springer publishing house, 1980
Individual evidence
- ^ Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA): Lärm. Retrieved March 2, 2020 .
- ↑ Deutsches Ärzteblatt, vol. 107, issue 9, March 5, 2010, p. A 364
- ↑ German statutory accident insurance e. V .: Recognized occupational diseases. Retrieved March 2, 2020 .
- ↑ "The changing world of work: Figures - Data - Facts" BAuA (2016)
Web links
- Preventing noise pollution - guidelines for the hörkomm.de project - barrier-free hearing and communication in the world of work