Extraction of the vocal tract area function by external stimulus

Knowledge of vocal tract area function is important for the understanding of phenomena occurring during speech production. We present here a new measurement method based on external excitation of the vocal tract with a known pseudo-random sequence, where the area function is obtained by a linear prediction analysis applied at the cross-correlation between the sequence and the signal measured at the lips. The advantages of this method over methods based on sweep-tones or white noise excitation are (1) a much shorter measurement time (about 100 ms), and (2) the possibility of speech sound production during the measurement. This method has been checked against classical methods through systematic comparisons on a small corpus of vowels. Moreover, it has been verified that simultaneous speech sound production does not perturb significantly the measurements. This method should thus be a very helpful tool for the investigation of the acoustic properties of the vocal-tract in various cases such as vowels.