Primary Research on Arabic Visemes, Analysis in Space and Frequency Domain

Visemes are the unique facial positions required to produce phonemes, which are the smallest phonetic unit distinguished by the speakers of a particular language. Each language has multiple phonemes and visemes, and each viseme can have multiple phonemes. However, current literature on viseme research indicates that the mapping between phonemes and visemes is many-to-one: there are many phonemes which look alike visually, and hence they fall into the same visemic category. To evaluate the performance of the proposed method, the authors collected a large number of speech visual signal of five Algerian speakers male and female at different moments pronouncing 28 Arabic phonemes. For each frame the lip area is manually located with a rectangle of size proportional to 120*160 and centred on the mouth, and converted to gray scale. Finally, the mean and the standard deviation of the values of the pixels of the lip area are computed by using 20 images for each phoneme sequence to classify the visemes. The pitch analysis is investigated to show its variation for each viseme.