A study of speech fractal dimensions

The fractal dimension (D) of a signal gives an estimate of its degree of fr eedom: which allows estimation of its fluctuations. Using 16 kHz time sampl ing and the box counting method we studied the Ds of some of the main stati onary parts of French speech, the phonemes [a], [e], [i], [o], [y], pronoun ced 4 times by 10 males and 10 females. Our study demonstrated that the sta tionary signal of vowels is not fractal, but may, at the smallest scale, pr ovide a kind of signature for each vowel, though the present categorization is not totally significant. Since the box counting method objectifies and quantifies the roughness of the signal, this procedure may be useful for cl inical applications. In case of dysphonia, moreover, these signatures could be perhaps be included in the speech signal processing of cochlear implant s.