Noise is often defined as unwanted sound. _The degree of ”unwantedness˝ is, however, a psychological question and may range from moderate annoyanceto various degrees of permanent hearing loss and will, furthermore, be rated differently by different observers.
It is therefore extremely difficult to answer „the question: ˝What is gained by reducing this particular noise˝.
However, it is generally recognized that the overall efficiency of human beings is considerably higher when they are performing their duties under satisfying and comfortable conditions than when they are constantly being ˝irritated˝ or annoyed by their surroundings.
Also, a certain degree of environmental quietness is a desirable quality in itself.
People in general do for instance, not like to live in the immediate vicinity of an airfield, of roads with heavy traffic or other more or less noisy places.
The noise may thus in these cases affect the prices of the nearby land and bear considerable economic importance.
Furthermore, in choosing utility items, such as refrigerators, vacuum cleaners, washing machines, air conditioning systems, oil burners etc. the noiselessness of the items is definitely consideredby the buyer.
The control of noise is therefore important not only from an annoyance and health point of view but also from an economic point of view.