An instrument worn by an individual to measure noise exposure is called a Noise Dosimeter, used to measure sound exposure, i.e., the time integral of the square of the instantaneous A-frequency weighted sound pressure. Its working principle is based on "equal energy exchange rate." For a constant sound level, doubling (or halving) the exposure time also doubles (or halves) the sound exposure; similarly, for a constant exposure time, an increase (or decrease) of 3 dB in the input sound level will double (or halve) the sound exposure. It meets the requirements of IEC 61672-1 for a Class 2 integrating sound level meter.

AWA5920 Noise Dosimeter