perceptual speech quality measurement (PSQM)

Perceptual Speech Quality Measurement (PSQM) is one of several methods for determining objective speech quality for telephony. PSQM is a method described by the International Telecommunication Union( ITU-T) under standard P.861, which is used to test low-bit-rate speech codecs.

In the PSQM method, a specified speech signal is injected at one end of a link and an objective evaluation of the output signal is performed at the other end using special calculation formulas. A psychoacoustic model is used to mathematically simulate the subjective perception. The result is an objective quality value, the so-called PSQM value, which can range from 0 to 6.5 and is transferred to the Mean Opinion Score( MOS). A low PSQM value corresponds to high speech quality, a high PSQM value to inferior to poor speech quality.

Other methods for determining speech quality include the Perceptual Analysis Measurement System( PAMS) and the Perceptual Evaluation of Speech Quality( PESQ), which can be seen as the successor technology to PSQM. Both PSQM and PAMS work according to mathematical algorithms and are based on the evaluation of natural male and female speech patterns. PSQM was withdrawn after the specification of PESQ.