PESQ is used for objective voice quality testing by phone manufacturers, network equipment vendors and telecom operators.
PESQ was developed to model subjective tests commonly used in telecommunications (e.g., Recommendation ITU-T P.800) to assess the voice quality perceived by human beings.
In order to characterize the listening quality as perceived by users, it is of paramount importance to load modern telecom equipment with speech-like signals.
Many systems are optimized for speech and would respond in an unpredictable way to non-speech signals (e.g., tones, noise).
PESQ results principally model mean opinion scores (MOS) that cover a scale from 1 (bad) to 5 (excellent).