Digital modeling of SPEECH SIGNAL

Speech Signal:

Vocal source: Lung, vocal cord and vocal gate

Vocal tract: start from voice gate till lip including throat and air tract.

In addition to that mouth cavity, nose cavity, lip.

Digital model

Simply we can represent speech signal using the schemes PCM,DPCM,DM etc..

For example PCM technique,

Applying sampling theorem to the digital signal of speech.(if the signal band width is W hertz then the sampling period must be T<= 1/2W.)

Measure of fidelity of PCM is SNR in this noise or error signal will be

Linear Predictive Method

This is the simple method to analyze speech signal

Basic idea sample of speech is approximated as linear combination of past speech signals.

Transfer function speech samples

Let speech signal be x(n)

With linear predictor

Predictor error will be

Predictor polynomial:

Use of Linear Prediction

Spectrum estimation : If the predictor polynomial is assumed to represent the denominator of the vocal tract transfer function, we can obtain frequency response of vocal tract as

Pitch detection

Speech synthesis.

Thank You…