A method and apparatus for assessing the perceptual quality of stereo speech signals transmitted via a telecommunications network and recorded acoustically from an acoustic terminal device in which a mono reference signal comprising a single channel is aligned with a degraded stereo signal comprising a left and a right channel; a delay between each channel of said degraded signal and said reference signal is estimated; a noise masking indicator in dependence upon said estimated delays is generated; the level of the stereo signals is adjusted in dependence upon said noise masking indicator; a set of perceptually relevant parameters for each of said reference and degraded signals are generated; the perceptually relevant parameters of the reference signal with the perceptually relevant parameters of the degraded signal to generate a disturbance profile are compared; and a speech quality prediction is generated in dependence upon said disturbance profile.
Speech quality assessment with noise masking