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
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