1. Speech Signal Processing IBy
Edmilson Morais And Prof. Greg. Dogil
Stuttgart, October 18, 2001

2. Goals of the Course Our part Your part ?
Basic theoretical concepts about
Speech Signal Processing - SDSP
Waveform generation for TTS systems - TTS
Automatic Speech Recognition (Statistical approach)- ASR
Fundaments of programing in Matlab
It will be the tool used for our simulations
Your part ?
Describe and justify the important aspects and drawbacks in the algorithm.
Next term: Speech Signal Processing II
Going deeper into more Theoretical and Pratical aspects of : SSP, TTS and ASR.

3. Tutorial of Matlab Principles of linear algebra Programing in Matlab
Vectors, Matrices, linear systems
Programing in Matlab
Variables, operators, ...
if statements, switch statements, for loops, while loops, continue statements, break statements, ...
I/O operations
Graphical visualization
Executable files
Subroutines

4. Matlab : Graphical visualization
[X,Y] = meshgrid(-8:.5:8);
R = sqrt(X.^2 + Y.^2) + eps;
Z = sin(R)./R;
mesh(X,Y,Z,'EdgeColor','black')
surf(X,Y,Z,'FaceColor','red','EdgeColor','none');
camlight left; lighting phong

5. Matlab : Graphical visualization – Optimization in a hiperbolic (quadratic) surface
Mean squared
error - E
Weight

6. SDSP : Looking through time
Speech signal : Analog and digital
amplitude
quantization
Sampling rate
time

7. SDSP : Transformation and Digital filters
Transformations
Z-Transforms, Fourier transforms
Digital filters
FIR, IIR

8. SDSP – Frame based analysis
Waveform multiplied for the hanning window : xw
Hanning window : w
Magnitude of the spectrum of xw
Freq. Response of the LP-filter

9. SDSP - Looking at frequency components through time
Current
Previous
Before smoothing
After smoothing

10. SDSP : Vector quantization
Voronoi Space : Centroid and Distortion meassure

11. TTS - Waveform generation for TTS
Analysis and Resynthesis – Coding and Decoding L P A n a l y s i ( z ) I v e r F t 1 c h M k o p S m g T R d u x E O C D f . U / V
Parametrization : Mapping the waveform into a set of parameters
Reconstruction: Synthesis of the waveform from the set of parameters.
Prosody : F0
Duration
Amplitude
A – LP coeficients
e – LP residue
En – Prototypes
Fo – Fundamental frequency
U/UV – Voiced / Unvoiced transitions

12. TTS - Waveform generation for TTS
Speech coding
Parametric coders, Waveform coders, Hybrid coders
TTS – Concatenative approach
Time scale and Frequency scale modifications
Spectral smoothings
Unit selection
Original
TTS
Original
Resynthesized
Modified : sin(x+)

13. ASR - Automatic Speech Recognition
Front-End Signal Processing
Feature extraction
Perceptual domain, Articulatory domain
Acoustic modeling
HMM : Hidden Markov Model
ANN/HMM : Hybrid models - Artificial Neural Network and HMM
Statistical Language Modeling
N-grammars, smoothing techniques
Search : Decoding
Viterbi, Stack decoding, ...

14. ASR – HMM - Topology
Ergotic model Left-right model

15. ASR – HMM – Basic principle

16. ASR – HMM - Viterbi alignment5 1 2 ( a ) b c d

17. ASR – HMM – Forward-Backward

18. ASR – ANN/HMM

19. Evaluation : Exercises and Simulations
List of Exercises
SDSP, TTS, ASR
Simulations
SDSP
Vector quantization
TTS
Waveform Interpolation
ASR
Acoustic modeling using : HMM and ANN+HMM
Language modeling
Decoding

20. Evaluation : Report Reports 4 pages, two colunms. Sections
Write the analysis and results of the simulation in a format of a paper
4 pages, two colunms.
Sections
Abstract
Introduction
Brief theoretical description of the method
Methodology used to perform the experiment
Results
Conclusions and suggestions for further works
Bibliograph

21. Days of classes Normal semester 2001
October : 18, 25, (01 is a hollyday)
November : 8, 15, 22, 29
December : 6,13,20
2002
January : 10,17,24,31
February : 7,14
Total : 15 days.
Option two
October : 18, 25
March : An one week block seminar : 1.5 hours a day.
Total : 13 days.
Option one
October : 16,18,23,25,30
November : 6,8,13,15,20,22,27,29
February : 5,7,12,14
Total : 17 days.
Option three
March : An one week block seminar : 3 hours a day.
Equivalent to 15 days