Speaker dependent changes in formants based on normalization of vowel triangle

In smoothed LPC speech signal spectrum, the local peaks are called formants. Their frequency and level depend on three basic aspects, namely on spoken phoneme, individual speaker as well as emotional state of speaker. This paper is focused on speaker analysis based on comparison of vowel formants with their normalized values. The novel method described here uses for formant normalization statistical values of formants presented in the form of formant planes. Formant normalization is made by average formant position given for Czech vowels. For each speaker the center of gravity of two vowel triangles are calculated; for the small vowel triangle created by /a/, /e/, /o/ vowels and for the big vowel triangle created by /a/, /i/, /u/ vowels. The differences between the individual and normalized center of gravity for both vowel triangles are represented as resulting vectors. Parameters of these vectors were analyzed in more details for statistical evaluation for a set of 12 male speakers. Best results were achieved for the /a/, /e/, /o/ triangle normalized by average formant position in the F2-F3 plane, where the vector angle and the vector length were totally different within analyzed speakers.