Obtaining LIP and Glottal Reflection Coefficients from Vowel Sounds

Knowledge about lip and glottal reflection coefficients during phonation is needed to eliminate their distortion effects on the estimates of vocal-tract area functions and glottal waves from vowel sounds. Direct measurements of these coefficients at human mouths are difficult. This paper presents a method for estimating them from vowel sounds. The estimation encounters an ill-defined inverse problem: the number of unknowns is greater than the number of constraints, and non-unique solutions exist for a sound. To overcome this problem, this paper uses a vowel sound produced by a subject whose vocal-tract area function (VTAF) for the sound is known. The estimates of the lip and the glottal reflection coefficients are determined as those that lead to a VTAF solution most similar to the known VTAF for the sound. The lip and the glottal reflection coefficients obtained for /a/ and /i/ are presented