DSP based real time implementation of an advanced analysis tool for audio channels

The Noise to Mask Ratio (NMR) meter is a device used to measure the audibility of error signals according to the laws of psychoacoustics. First introduced in 1987 (6), NMR has since then been further improved and implemented in real time. Its growing importance is related to source coding algorithms (and similar algorithms) which are also based on psychacoustic effects. The following article recaps the working principles of NMR and describes the real time implementation aspects. Application of NMR to several source coding schemes is shown, concluded by an outlook into the future of NMR.