1. Speech and Audio Processing
Preeti Rao
Department of Electrical Engineering,
I.I.T. Bombay (

2. Research Activities
Speech processing : low-rate coding, speech synthesis
Audio signal processing : audio compression, audio content retrieval
Major project: low-rate (< 2kbps) codec for telephone bandwidth speech (sponsored by B.E.L.)

3. Current Coding Standards A Perspective

4. LR-HNM Model: Parameters
Windowed speech
HNM Model Parameter Estimator
Pitch
Spectral amplitudes
Voicing cutoff frequency

5. Speech Codec Block Diagram
Frame Size = 20 ms
Sampling Rate = 8 kHz

6. Performance Bit rate : 1.55 kbps Delay : 60 ms
Complexity : 40 MIPS (tentative)
Quality : average MOS = 3.0 (as obtained from objective measures)
Robustness to background noise : enhancement preprocessor needed below 6-8 dB SNR

7. A “Query-by-Humming” System (under development, jointly with Prof. S
A “Query-by-Humming” System (under development, jointly with Prof. S. Dutta Roy)