The ITU-T Recommendation for Single-Ended Method for Objective Speech Quality Assessment in Narrow-Band Telephony Applications, an automated method for evaluating the quality of voice transmissions. P.563 is characterized as non-intrusive, as it does not require inserting a reference signal into the device being tested and does not require the generation of test traffic. See also
P.800,
P.861,
P.862, and
narrowband.