Normalised Noise Energy (NNE) is an acoustic measure of the voice assesses the relative level of vocal noise to that of harmonics, but bases the analysis on a relatively small number of vocal periods (as opposed to individual cycles as in the HNR) and is therefore much faster to calculate. This has an added advantage that it avoids the effects of drift in fundamental frequency or intensity during the utterance which can be a problem in the calculation of the noise component of the HNR.