05-07-2012, 03:29 PM
audio signal processing
[attachment=26882]
Speech data analysis techniques
Filter banks can also be non-uniform
LPC and Cepstral LPC parameters
Vector quantization method to represent data more efficiently
Filtering method
For each frame (10 - 30 ms) a set of filter outputs will be calculated. (frame overlap 5ms)
There are many different methods for setting the filter bandwidths -- uniform or non-uniform
How to determine filter band ranges
The pervious example of using 4 linear filters is too simple and primitive.
We will discuss
Uniform filter banks
Log frequency banks
Mel filter bands
Pre-emphasis
The high concentration of energy in the low frequency range observed for most speech spectra is considered a nuisance because it makes less relevant the energy of the signal at middle and high frequencies in many speech analysis algorithms.”
From Vergin, R. etal. ,“"Compensated mel frequency cepstrum coefficients ", IEEE, ICASSP-96. 1996 .
Vector Quantization (VQ)
Vector quantization is a data compression method
raw speech 10KHz/8-bit data for a 30ms frame is 300 bytes
10th order LPC =10 floating numbers=40 bytes
after VQ it can be as small as one byte.
Used in tele-communication systems.
Enhance recognition systems since less data is involved.
[attachment=26882]
Speech data analysis techniques
Filter banks can also be non-uniform
LPC and Cepstral LPC parameters
Vector quantization method to represent data more efficiently
Filtering method
For each frame (10 - 30 ms) a set of filter outputs will be calculated. (frame overlap 5ms)
There are many different methods for setting the filter bandwidths -- uniform or non-uniform
How to determine filter band ranges
The pervious example of using 4 linear filters is too simple and primitive.
We will discuss
Uniform filter banks
Log frequency banks
Mel filter bands
Pre-emphasis
The high concentration of energy in the low frequency range observed for most speech spectra is considered a nuisance because it makes less relevant the energy of the signal at middle and high frequencies in many speech analysis algorithms.”
From Vergin, R. etal. ,“"Compensated mel frequency cepstrum coefficients ", IEEE, ICASSP-96. 1996 .
Vector Quantization (VQ)
Vector quantization is a data compression method
raw speech 10KHz/8-bit data for a 30ms frame is 300 bytes
10th order LPC =10 floating numbers=40 bytes
after VQ it can be as small as one byte.
Used in tele-communication systems.
Enhance recognition systems since less data is involved.