Leq encompasses a set of sound level meter specifications, which are described in detail in the BS EN 61672-1 European Standard.
Pure Analyzer implements the following Leq measurements: time-weighted sound level, time-average sound level and sound exposure level.
Frequency weighting is employed for all measurements, A being the standard and default, although other weightings can be specified if necessary.
The Leq module always measures the audio routed through the Mic channel.
LA is the root-mean-square sound level obtained after exponential time weighting.
Exponential averaging has the effect of progressively ‘forgetting’ past sample values.
The norm specifies two time-weighting constants:
The corresponding letter symbol is LAF for an A-frequency weighted and F time-weighted sound level, for example.
Time-average sound level is basically an RMS meter with frequency-weighting applied.
This measures the sound exposure equivalent to a ‘dose’ received for a second. It is useful for determining the amount of sound pressure to which listeners have been exposed for a certain duration.
This value naturally increases with time. For a constant source level, this value increases in a logarithmic fashion.