Speech Processing by Computer

 

LECTURE 3

DIGITAL FILTERING

 

 

Objectives

 

By the end of the session you should:

understand that the basic building blocks of digital filters are poles and zeros

understand that poles form resonators defined by their resonant frequency and bandwidth

understand that complex systems can be constructed by cascading simple systems

be able to explain how a low-pass filter can be designed by careful selection of resonators

have a qualitative understanding of how band-pass and high-pass filters can be constructed along similar lines to low-pass filters

be able to identify applications for filterbanks

understand how a filterbank can be constructed to deliver estimates of energy over a range of frequencies.

understand how a filterbank can also be used to synthesize speech

 

Outline

 

3.      Digital Filtering

3.1.   System modelling with poles and zeros

3.1.1.      Non-recursive digital systems are all-zero systems

3.1.2.      Purely recursive digital systems are all-pole systems

3.1.3.      Positioning poles and zeros on response plot

3.2.   Simple filter designs

3.2.1.      Low-pass filter designs

3.2.2.      High-pass and band-pass transformations

3.3.   Filterbank analysis/synthesis

3.3.1.      Bank of bandpass filters

3.3.2.      Rectification

3.3.3.      Smoothing

3.3.4.      Source parameters

3.3.5.      Re-synthesis

 

Reading

 

MATLAB Users:

MATLAB Signal Processing Toolbox Help: Filter Requirements and Specification

 

General:

C. Speaks, Introduction to Sound, Singular Press, 1996, Chapter 6. , Resonance and Filtering