Quasi-peak

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Quasi-peak means 'not quite peak', or 'aiming towards peak but not actually peak'. The term is commonly used when referring to electronic detectors or rectifiers. Despite the above definition, the term quasi-peak should not be interpreted as vague in any way. Actual quasi-peak detectors for specific purposes usually have precisely defined dynamic characteristics, in tems of 'attack time', 'integration time', and 'decay time' or 'fall-back' time.

In Audio quality measurement quasi-peak rectifiers are specified in several standards. For example ITU-R 468 noise weighting uses a special rectifier incorporating two cascaded charging time constants. The PPM or Peak programme meter used to measure programme levels is actually a quasi-peak reading meter, again with precisely defined dynamics. Flutter measurement also involves a standardised quasi-peak reading meter. In every case the dyamics are chosen to reflect the sensitivity of human hearing to brief sounds, ignoring those so brief that we do not perceive them, and weighting those of intermediate duration according to audibility.

Quasi-peak detectors are also used in the measurement of electromagnetic compatibility.