Classification of Russian Vowels Spoken by Different Speakers

The problem of speaker normalization is investigated for classifying the Russian vowels. The known methods of normalization of formants F1 and F2 which make their normalized values F1N and F2N invariant to compression or expansion and to parallel shift are mentioned. A new statistical method of normalization is then suggested. All of these methods are compared using an index of normalization quality (η). The result of the comparison shows that the normalization suggested in this letter has the largest index, not only on the average but also for each individual vowel pair. The procedure of classification of the Russian vowels using a self-normalized formant plot is shown at the end of the letter.