Acoustic dose meter - gives output proportional to intensity and duration of sound

摘要

To evaluate the influence of noise on the human body, a portable instrument can be used to measure the noise intensity and its duration. A sound measuring system uses a microphone (1) to convert sound into electronic signals. These signals are amplified (2) and filtered, to give the effects of noise in a certain bandwidth, and then a non-linear circuit gives a voltage proportional to the logarithm of the measured acoustic pressure. A reference threshold level is inserted. The output is indicated by an electrolytic integrator (3) in whch the displacement of mercury ions in an electrolyte gives a movement of mercury proportional to the intensity and duration of the noise present.