A method for estimating a subjective quality of a signal carried over a transmission path. The transmission path is monitored at periodic intervals. For each of the periodic intervals, at least one impairment factor is measured, an estimated effect of each of the impairment factors is determined using at least one value, and an estimated subjective quality of the signal is determined using the estimated effect of each of the impairment factors. Further, an estimated combined subjective quality of the signal is determined using the estimated subjective quality for at least two of the periodic intervals.