Viop

PSQM

PSQM evaluates the quality of voice signals in much the same way that nonlinear codecs encode and decode voice signals. It evaluates whether a particular voice signal is distorted according to what a human listener would find annoying and distracting. To do this, PSQM takes a clean voice sample and compares it to a more or less distorted version using a complex weighting method that takes into account what is perceptually important — for example, the physiology of the human ear and cognitive factors related to what human listeners are likely to notice. PSQM provides a relative score that indicates just how different the distorted signal is with respect to the original from the perspective of the human listener via the algorithm. PSQM shows whether the distorted voice signal is better or worse than the original. Because of the way PSQM works, this distortion score corresponds very closely to how a statistically large number of human listeners would react in the same test situation (for example, MOS). PSQM was originally and specifically designed to measure the perceived quality of voice as impacted by voice compression codecs. However, certain impairments, such as packet loss, introduced by data network transmission, are not adequately reflected in PSQM scores. Therefore, an enhanced version of PSQM, known as PSQM+, was developed to correlate more to MOS scores in the presence of network impairments.