Acoustic instruments to measure sound (sound level meters - see Fig. 1) and related equipment such as sound calibrators (see Fig. 2), as well as instruments to measure human hearing functions, (audiometers - see Fig. 3), are not usually subject to legal control. In Europe, only a few countries (for example Austria, Czech Republic, France, Germany, Poland and Switzerland) prescribe type approval based on pattern evaluation and/or regular verification of individual instruments. The situation is similar outside Europe, which is surprising considering that millions of people suffer from excessive noise, especially in industrialized countries. Manufacturers and communities spend large sums reducing noise, but for this to be effective any action must be based on precise noise measurements. These were good reasons to include sound measuring instruments used for official traffic noise measurements in the scope of legal metrology in Germany in 1972. Later on, the use of verified sound level meters and related equipment was also prescribed for other types of environmental noise. Results of pattern evaluations carried out at the PTB and of verifications of individual instruments fully justified these regulations [1]. Similarly, noise-induced hearing loss of workers in industry is still one of the most frequent occupational hazards and insurers frequently end up paying out compensation. Such compensation is based on the exact measurement, by means of pure-tone or speech audiometers, of the hearing impairment due to noise.
展开▼
