Formants Analysis

Three Formants Analysis

In order to view the changes of more than 2 formants over time, the formants of all frames can be plotted in a 2-D graph. The results are shown in following figures for two different speakers.

Formants of “five” spoken by a male speaker

Formants of “five” spoken by a female speaker

The circles on each graph show the location of the voiced region for /ai/ in digit “five”. Even that two speech signals are from different speakers of different gender, a few common properties can be seen from the graphs. Firstly, the voiced regions have respectively high amplitude compare to unvoiced region. The normalized amplitudes are shown with the intensity of the star marker (*). The darker markers indicate higher amplitudes. Secondly, there is a trend for the changes of diphthong in the voiced region, and the formants can be classified into certain ranges.

Speech Analysis using LPC

Writting a speech analysis tool is not difficult if you choose a good software you are familiar to. Some useful software could be found at the sidebar of this blog. I have written some tools for speech signal analysis using MATLAB for the sake of speech signal studies. It could be found at the matlabcentral:

http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=8779&objectType=FILE

This GUI is designed to extract and visualize the spectrum of FFT and LPC of a specific frame, or a window. Following figure shows the LPC spectrum of a frame with 256 samples. The indicator on the upper subplot shows the location of the specific frame.