The SPL Fast function is sampled 10 times per second to generate the statistical distribution function. The dynamic range (130 dB) is divided into classes of 0.2dB class width. During a measurement, each sample is put into one of the classes. After some seconds there are samples enough to have a look at the distribution function of the sound level.

Up to eight percentiles (statistical values) will be shown numerically (and saved with the measurement). The statistical distribution calculation applies to the spectral weighting networks (A, C and Z) as well as all the individual filter bands (if applicable). The complete statistics can, however, be shown in two different graphs called “distribution” and “cumulative distribution”.