The principle of the method consists of determining the equivalent continuous A-weighted sound pressure level (LAeqT) using a class 1 integrating-averaging sound level meter. The determination of LAeqT can be carried out:
- by continuous measurement over the time interval T;
- by measuring the equivalent continuous A-weighted sound pressure levels over subintervals of time within T in which the noise is stationary, LAeqT being obtained by calculation based on the results of these measurements;
- by measuring the sound exposure levels of individual events that occur within the time interval T, LAeqT being obtained by calculation based on the results of these measurements;
- by combining the methods presented above.
The measurements are carried out in the field, and determinations may be supplemented by calculation steps, including the use of validated specific software. Sampling can be performed continuously over the period of interest or sampling methods may be used. In addition to LAeqT, the laboratory may also measure and report other acoustic indicators considered useful for characterizing noise pollution (LAFmax, LAF90T, etc.).