Analysis

1
Analysis Synthesis

• The Vocoder and its related technology

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(Extremely) Simplified Model of Speech Production
Periodic source
Filters
voiced
Coupling
Speech
unvoiced
Noise source
7
(Slightly less) Simplified Model of Speech
Production
pitch
Impulse train
V/uv bit
Glottal model
Filter spec
voiced
Gain v
Coupling
x
Filters
Speech
Gain u
x
unvoiced
Noise source
8
Glottal Waveform Caricature
Glottis closed (decoupled)
Glottis open (nonlinear)
9
Channel Vocoder, Synthesizer component
10
Channel Vocoder, Analyzer component
11
Vocoders vocal tract synthesis

• Short time spectral synthesis
• Linear predictive synthesis
• Cepstral synthesis
• Formant synthesis

12
Vocoders vocal tract analysis

• Short time spectral analysis
• Linear predictive analysis
• Cepstral analysis
• Formant analysis

13
Vocoders vocal source analysis

• Pitch detection
• Voiced/unvoiced decision

14
Fine structure and Spectral Envelope
15
Narrow and wideband filterbank spectral analyses
16
Wideband spectrogram
17
Figure 3.5 Narrow band spectrogram
Narrowband spectrogram
18

• Source-Filter Separation by Cepstral Analysis

19
LPC spectral envelope estimation
20
Formant Analysis

• Peak picking from smoothed spectrum
• Root-finding from LPC polynomial - finding
  second-order sections
• In general, position more important than
  bandwidth
• Deterministic or statistical analysis to find
  best formant track

21
Ed Lee Vocoder Page
http//ptolemy.eecs.berkeley.edu/eal/audio/vocode
r.html
22
Linux Vocoder Page
http//www.sirlab.de/linux/descr_vocoder.html