Figure 7. Speech signal after FFT-Development an Automatic Speech to Facial Animation Conversion for Improve Deaf Lives

Use of speech spectrum for changing the work domain on the signal from time to frequency
is used via Fourier conventions. The rapid and practical way of estimating Spectrum in such
applications is employment of rapid Fourier transform. The final stage is extracting particularities is
use of discrete cosine to return particularities to the time domain and converse FFT approximation.
Major advantage of this method is decrease of number of particularities of number of filter from f N
to c N in which c f N ≤ N . In addition, doing so, includes making independent of the obtained
particularity and rendering them non dependant which leads matrix covariance features to become
axial. The following equation shows this point.