| Author: | Yuen, Siu-keung |
| Title: | Variable rate code excited linear predictive coding of speech |
| Degree: | M.Sc. |
| Year: | 1997 |
| Subject: | Speech processing systems Coding theory Hong Kong Polytechnic University -- Dissertations |
| Department: | Multi-disciplinary Studies |
| Pages: | vi, 97 leaves : ill. ; 30 cm |
| Language: | English |
| Abstract: | This thesis presents a variable rate Code-Excited Linear Predictive (CELP) [9] speech coding which can be applied to communication and consumer products. The coder can run at either 7.35 kbps for voiced speech or 2.1 kbps for unvoiced speech under an adaptive rate selection algorithm based on QCELP [4] concept. The objective of this thesis is to simulate the variable rate CELP speech coder in software, and evaluate the rate determination and speech quality using objective measures. The CELP coding algorithm is presented in detail with balanced theory and practical consideration. Some variable rate coding algorithms such as VAD, QCELP, and phonetic classifications are outlined. Speech evaluation techniques such as objective and subjective measures are also described. A software based variable rate CELP coder is developed for simulation. With quantization, the coder achieves on average 8.9 dB segmental SNR at an average bit rate of 6.2 kbps. The effect of speakers, input level variations, and input signal to noise ratio variation are also evaluated. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b13986405.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.24 MB | Adobe PDF | View/Open |
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