Castle Group Ltd

When measuring noise levels Lmax and Peak should not be confused. Lmax is the RMS (root mean squared) maximum level of a noise source or environment where peak is the maximum level of the raw noise source.

RMS, or root mean squared, is a measure of the magnitude of the varying noise source quantity. The name derives from the calculation, from either a series of discreete values or a continuous varying function, of the square root of the mean of the squares of the values.

The reason for using RMS values gives a clearer understanding of a noise level, making calculations and measurements easier for a noise source waveform which is changing constantly in its magnitude.

Lmax is the highest RMS sound pressure level within the measuring period.

Lmin is the lowest RMS sound pressure level within the measuring period.

Peak is the crest of the sound pressure within the measuring period. (This is not a RMS level!)