AES Standards News Blog

The Call for Comment on DRAFT AES75-xxxx, "AES standard for acoustics – Measuring loudspeaker maximum linear sound levels using noise" was published 2022-01-10

This standard details a procedure for measuring maximum linear sound levels of a loudspeaker system or driver using a test signal called M Noise. In order to measure maximum linear sound levels meaningfully and repeatably, a signal is required whose RMS and peak levels as functions of frequency have been shown to be representative of program material. Various existing standards define noise based test signals which, like M Noise, have incorporated the knowledge that typical program material has a diminishing RMS level with increasing frequency, but M Noise uniquely also features a relatively constant peak level as a function of frequency, so that the crest factor (peak level – RMS level) increases with frequency, which an analysis on a large variety of music and other content has revealed is an important additional characteristic of typical program material. The specified procedure determines a loudspeaker’s maximum linear sound levels by incrementally increasing the Playback Level of M Noise until a stop condition is met: either an unacceptable change in the transfer function’s magnitude or an unacceptable change in the coherence of the transfer function.

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