Noise is undesirable sound (e.g., machine noise, acoustic tones, explosion or impact noise, high-decibel music, irritating speech sound) that may give rise to hearing impairments or other damage to health. Noise-induced hearing loss tops the statistics for occupational disorders. Intense noise at the workplace may affect the hearing of workers. In Germany, about 5 million employees are exposed to noise which presents a risk of hearing impairment.

Health effects of high noise exposure

Elevated noise levels, such as high-decibel music or loud traffic sounds, may depress the hairs on the hair cells. These hairs will then conduct sound less effectively, at least until they have reverted to their upright position. The noise of an explosion, or many years of continuous noise exposure at the workplace, may cause them to collapse or break off altogether. The result will be irreparable loss of hearing, since these hairs will not grow again.

Hearing is one of our brain‘s main sources of sensory input. Uncomfortable noise distracts us. As a result, we experience loss of concentration, fatigue, a reduced capacity to work due to increased physical strain, attention deficits, and an impaired ability to communicate verbally. Hardness of hearing is incurable. Hearing aids can provide only a limited improvement. This makes noise protection all the more important.

Regulations and exposure action values

In measuring sound levels, a filter is used to simulate the response of human hearing. This filter is referred to as the “A-filter”. Sound intensity is commonly measured in decibels = dB(A). In February 2003, the European Parliament and the European Council published EC Directive 2003/10/EC which defines the limits of noise exposure for workers. Like its predecessor, the new directive places primary emphasis on the duty to achieve technical noise abatement.

In the German implementation of this directive in the noise and vibration work protection directive, a distinction is made between two values for the daily exposure level: The lower trigger value of 80 dB(A) and the upper trigger value of 85 dB(A).

Prevention measures

An employer must provide hearing protectors when noise levels exceed the lower exposure action value. However, the use of such equipment becomes mandatory only when the upper exposure action value is reached or exceeded. Workers are required to wear hearing protectors in high-noise areas, which need to be expressly marked as such. Machines represent a main source of noise at the workplace. It follows that the call for noise abatement “at source”, i.e., on the machinery in question, is a key factor in the noise control concept.


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