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    Tuesday, September 27, 2005

    Speech Recognition: Formants for Vowels Classification (I)

    1. How to classify vowels for speech recognition?

    Different ways are used for this purpose; however, the most basic approach might be the use for “Formants” for classification.

    You might use the search engine or the google search bar at the side bar of this page to search for “speech classification


    2. What is formant”?

    Formant is the natural frequencies or resonances produce by the vocal track when someone speaks. The following figure shows the typical FFT spectral and the spectral for LPC autocorrelation method for a segment of speech spoken by a male speaker. From the LPC spectral, three resonances of significance can be noticed, and named as F1, F2 and F3 respectively



    3. How to find the formant values from the LPC coefficients?

    Visually it can be obtained easily, but not accurate. To obtain the formants numerically for mathematically, 1st you can perform the search on the data itself. 2nd, by taking the angle of roots of LPC coefficients, you actually obtain the formants.

    4. How to perform classification for the vowels using formants?

    Theoretically after you’ve obtained the formants, the classification task can be easily performed using simple classification methods, as well as NN methods.

    You might use the search engine or the google search bar at the side bar of this page to search for “speech recognition

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