What is noise?
Our environment is becoming louder and louder, and private and public transport is constantly increasing. No one is safe from noise. Even quiet locations can be exposed to high noise levels overnight. But: What is noise? Noise is defined as any type of sound that is perceived as disturbing, annoying or painful. Ambient noise consists of a variety of tones of different frequency and intensity. The specific perception by the human ear is taken into account when determining the noise intensity. Lighter tones are subjectively perceived as louder than darker ones. The loudest sound a person can hear painlessly has a sound intensity ten trillion times higher than the quietest. The hearing copes with perception by perceiving a tenfold increase in sound intensity as a doubling of the volume. Handling such large numbers is not very practical, so a logarithmic scale is used. The unit is the decibel (dB) derived from the Bel (B) (1 Bel = 10 decibels), a dimensionless ratio corresponding to the logarithm of 10.
Sources of noise and perception
The following figure shows some typical types of noise with their volume (in decibels) and subjective perception.