The effects of voice disguise upon formant transition

The second degree polynomial approximation coefficients of formant transition and transition duration, as the speaker specific aspects, have been studied under normal and diguised speech conditions. The speech material in this study consists of 10 segments occuring in a text read by twenty speakers. The selected disguise condition includes: a) heightened voice, b) lowered voice, c) pinched nose, which are frequently found in criminalistic cases. The most important results are: a) The approximation coefficients and transition duration are more different among the speakers than among the speech conditions. b) There are regular deviation trends for formant transitions from one speech condition to the others. c) The transition duration and the approximation coefficients can be used to identify speaker.