METHOD AND DEVICE FOR DETERMINING THE QUALITY OF A SPEECH SIGNAL

Methods and devices for objectively predicting perceptual quality of speech signals degraded in a speech processing/transporting system which may have poor prediction results for degraded signals including extremely weak or silent portions. Improvement is achieved by applying a first scaling step in a pre-processing stage with a first scaling factor which is a function of a reciprocal value of power of the output signal increased by an adjustment value, and by a second scaling step with a second scaling factor which is substantially equal to the first scaling factor raised to an exponential value and with an adjustment value between zero and one. The second scaling step may be performed at various locations in the device. The adjustment values are adjusted using test signals with well-defined subjective quality scores.