Study And Design On Connected Mandarin Digit Speech Recognition Based On DSP

In order to overcome the disadvantages of traditional Mandarin Digit Speech Recognition System, including bad robust and low recognition rate, this thesis elaborates the theory and practice of design of Connected Mandarin Digit Speech Recognition (CMDSR) system based on TMS320VC5402 fixed point Digital Signal Processor (DSP). This thesis tries to update the CMDSR system to achieve the characters below: real-time, better robust, higher recognition rate, non-special-man. Considering the disadvantages of traditional Improved Spectrum Subtraction Speech Enhancement, this thesis proposes the theory of Fuzzy Spectrum Subtraction based on the Fuzzy Theory and Improved Spectrum Subtraction Speech Enhancement; as for the difficulties of detecting the endpoint of speech signal, the thesis gives the table of initial and the improved parameters, with which we can confirm the endpoints of Mandarin Digit Speech; the thesis puts forward two-level digit real-time speech recognition system, the first level is based on Discrete Hidden Markov Model which is Linear Predictive Coding Cepstrum (LPCC) and Difference Linear Predictive Coding Cepstrum (DLPCC) , the second level is based on formant parameters; as for the realization of hardware, the thesis depicts the realization of every part of CMDSR based on the TMS320VC5402 in detail; as for the development of software, the thesis gives the software design flow chart of CMDSR, simulates the basic theory with MATLAB language and gives the simulation results.At last, the thesis establishes Mandarin Digit Speech Recognition Simulation System (MDSRSS) and Connected Mandarin Digit Speech Training System (CMDSTS) separately; with the CMDSTS, the thesis gets two sets of Vector Quantization (VQ) parameter table, including man's and woman's, besides, it gets two sets of non-special-man CMDSR Discrete Hidden Markov Model (DHMM) parameters, including man's and woman's as well. With the tables and parameters, the MDSRSS can recognize the input digit speech successfully and it also has better robust character.