The World Health Organisation (WHO) has identified noise (colloquially known as noise) as the second greatest environmental threat to physical and mental health in Europe. People who are exposed to high or constant levels of noise often suffer from cardiovascular and metabolic diseases. In addition, noise can have significant effects on performance and sleep, generally increasing stress levels, and people's mental health can also be affected. This can also have a lasting impact on the quality of life through irritability, hearing disorders and even tinnitus.
Definition: What exactly is noise?
Noise is any unwanted, usually loud sound. Ears pick up these sounds and process their information. The stronger the noise, the more people perceive it as unpleasant noise. Nevertheless, the concept of noise is subjective. Noise from a children's playground, for example, can be judged very differently - from negative to pleasantly positive - depending on the listener and the situation he or she is in.
Incidentally, the original meaning of the word noise comes from Italian and means "to arms" - all'arme is connected with the German word Alarm. In legal texts, a very simple definition of noise can be found: according to this, noise is simply "unwanted sound".
A distinction is made between continuous noise, intermittent noise and impulse noise:
- Continuous noise comes, for example, from machines such as pumps or blowers and describes noises that occur constantly over a longer period of time.
- The sound of a plane taking off or the warning tone of the air-Q when it warns the occupants of the house about carbon monoxide. This type of noise is called intermittent noise because the sound level increases and decreases quickly.
- Finally, impulse noise triggers events that are very brief - such as an explosion or a bursting balloon.
Typical sources of noise are listed below. This results in different perceptual contexts and different noise effects:
- Road traffic noise, rail traffic noise, aircraft noise
- Commercial and industrial noise
- Construction site noise
- Neighbourhood noise, recreational noise
Measuring noise: From the hearing threshold to the pain threshold
Noise can only be measured via the physically describable sound. Noise is created by vibrations and propagates in the air as sound waves. The volume depends on the strength of the sound. The sound pressure is measured and displayed as a sound pressure level in decibels. Each such sound event is represented as the smallest pressure fluctuation around the atmospheric air pressure. The oscillations are detected by the human ear.
How much the volume is perceived as annoying depends largely on the sound pressure and its pitch. Generally, a sound pressure level of 120 to 140 decibels is described as a pain wave. This is measured as frequency, i.e. air pressure fluctuations per second, in hertz. If the frequency is high, the human auditory system also perceives the sound higher. However, the complex organ perceives low and very high tones as less loud than tones of medium frequency. Thus, sounds of different frequencies can be perceived as equally loud at different sound pressure levels.
To take this physiological circumstance into account, the sound pressure level is measured according to the A-weighting filter. The filter adjusts the measured sound pressure level to the human perception of sound. The correction is based on the A-weighting curve, which corrects sound levels with low as well as high frequencies downwards because they are perceived more quietly by the human ear. The valid unit is dB(A). The air-Q air analyser measures the sound pressure level in the range 30 to 109 dB(A) at a frequency of more than 200 hertz(see data sheet). The resolution is 1 decibel, with an accuracy of ± 2 decibels.
What are the noise limits in Germany?
In order to prevent health impairment, the World Health Organisation has issued recommendations for maximum sound levels. For longer-term noise levels, a limit of 65 decibels during the day and 40 decibels at night applies. By comparison, the most important cause of noise in Germany is traffic noise caused by traffic on the road, in the air or by rail. More than one in three European residents is exposed to road noise of 55 decibels for extended periods of time. While noise from railways or other rail vehicles is perceived as having relatively little impact on sleep at night, aircraft noise plays the biggest role here.
There is a separate regulation specifically for noise in the workplace, which is laid down in the Noise Vibration Workplace Protection Ordinance (LärmVibrationsArb SchV). The limit value varies depending on the type of activity, its duration and the specific location. In addition, the volume of the noise that occurs for a short time (impulse noise) is also relevant. From the employer's point of view, taking certain protective measures is obligatory according to a directive of the EU Parliament and Council from 2003:
- If a worker is exposed to a sound level of 80 dB(A) or to impulse noise with high sound pressure of 135 dB(C) for a prolonged period of time, the employer has the duty of information or instruction. The employer must provide hearing protection. (Lower exposure action value)
- If the worker is exposed to the sound level of 85 dB(A) or impulse noise of 137 dB(C) for a longer period of time, the employer must not only provide the hearing protection but also monitor its use. (Upper exposure action value)
- The sound protection must be such that 87dB(A) is not exceeded as the maximum permissible sound level during the eight-hour working period. For this purpose, the exposure value is measured at the ear while wearing sound protection.
Noise and its effects on well-being
Basically, high sound peaks as well as continuous sound stress the human hearing. The so-called hair cells of the inner ear can be significantly damaged by noise. This leads to a restriction of acoustic perception. The problem is that these hair cells do not grow back: damage caused by noise is therefore irreparable and can ultimately lead to hearing loss. In addition, chronic or temporary ear noises such as tinnitus are also possible.
The NORAH Study presented at the end of 2015 is considered one of the most comprehensive international studies to date on the effects of noise from air, rail and road traffic on the health and quality of life of the population. Nine renowned research and specialist institutions, including from the fields of social science, psychology, acoustics and physics, had joined forces to investigate noise, particularly in the Rhine-Main region.
As a result, this study confirms that all three types of traffic noise lead to increased cardiovascular risks. A direct connection between chronic noise exposure and depression has also been established for the first time. However, the assumption that noise has an influence on blood pressure was not confirmed. More information on the NORAH Study is available here.
Noise reduction: What is being done about excessive noise pollution?
More and more often, representatives of cities and residents are facing each other in court because of high noise pollution. In Heidelberg, for example, there is a dispute about noise in the old town concerning closing times of catering establishments - which are sometimes at 4 a.m. out of consideration for the city's high student population. Previously, residents had taken noise measurements and found unacceptable levels of pollution. The administrative court had stipulated a night-time quiet period of at least six hours - and the city appealed against this; the end is open.
In North Rhine-Westphalia, an action alliance called NRW wird leiser (North Rhine-Westphalia becomes quieter ) has been formed, which, for example, advocates for limited usage times of classically operated leaf blowers. Such leaf blowers, which are also controversial because they shred small animals, for example, cause noise of up to 91dB(A) if you are within a radius of three metres. In Dorsten, leaf blowers may therefore only be used to a very limited extent. It would be better if alternatives with rechargeable batteries were used.
If you want to know exactly how much noise you are exposed to in your flat, house or workplace, you can get a measuring device like the air-Q to visualise both short-term sound levels and longer-term continuous exposure.
(Image: Pixabay/ Alexey Chizhov)
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