1. A single-ended speech quality measurement method comprising the steps of: extracting perceptual features from a speech signal that has been processed by network equipment, transmitted on a communications link, or both; assessing the perceptual features with statistical models generated prior to extracting the perceptual features to form indicators of speech quality; and employing the indicators of speech quality to produce an estimate of subjective speech quality score without reference to a corresponding speech signal that has not been processed by network equipment, transmitted on a communications link, or both.