The last level is the segmentation into notes and phones . Decision functions on the set of features have been built and provide the segmentation marks. For research purposes, a graphical interface has been designed to allow visualisation of these features, the results of the decisions, and the final result. For the source level the mean and the variance of the features are computed on sound segments of one second or more. Various classification methods are used which are trained with data sets collected by sampling radio broadcasts and movie sound tracks.
Segmentation starts with the source level.
Information obtained at a given level is propagated towards the other levels. For example, in case of instrumental music and the singing voice, if vibrato is detected at the feature level, amplitude and frequency of vibrato are estimated and are taken into account for the notes and phones level. The vibrato is removed from the fundamental frequency trajectory, and the high frequencies of the signal are not used in spectral flux computation. A complete feature extraction and segmentation system is demonstrated. Applications and results on various examples such as a movie sound track are presented.