Speech quality assessment with noise masking

An apparatus for assessing the perceptual quality of speech signals transmitted via a telecommunications network and recorded acoustically from an acoustic terminal device comprising:

• a front end processor for aligning a mono reference signal comprising a single channel with a degraded stereo signal comprising a first channel and a second channel, said front end processor comprising a leveller for adjusting the power levels of said signals and a time aligner for determining the estimated delays for each of said channels of said degraded signal;
• an auditory transformer for generating a set of perceptually relevant parameters for each of said signals;
• and
• a comparator for comparing said perceptually relevant parameters to generate disturbance profiles;
• and
• a modeller for generating a speech quality prediction in dependence upon said disturbance profiles;
• in which said front end processor further comprises
• a noise masking determiner for comparing signal parameters of each of said channels of said degraded signal and generating a noise masking indicator in dependence upon said parameters;
• and in which said disturbance profiles are dependent upon said noise masking indicator.