A method for use in speaker verification, comprises: receiving a sample of a person's speech; estimating a noise measure in the received sample of the person's speech; if the estimated noise measure does not meet a predetermined criterion, rejecting the received sample of the person's speech; and if the estimated noise measure meets the predetermined criterion: adding noise to the received sample to form a sample with increased noise; extracting features of the sample with increased noise; and forming a model of the person's speech from the extracted features.