||This thesis presents the implementation of an adaptive feedback active noise cancellation (ANC) system for headphone application utilizing TMS320C6713 DSP Starter Kit. |
The experiment in this study was divided into two sections: the software simulation and the headphone implementation. In this research, the speech and noise were used the same in two parts. Noise was divided into three sections: single frequency noise, dual frequency noise, and multi-frequency noise. And the speech was recoded from the laboratory senior. In the first part, this research used MATLAB to compare three ANC algorithms: Filtered-X Least Mean Square (FXLMS), Filter-X Normalized Least Mean Square (FXNLMS), and Leaky Filtered-X Least Mean Square (Leaky-FXLMS). The denoising performance of the three algorithms with and without speech output from the headphone were simulated. The most effective method of algorithm in reducing unwanted noise was chosen. In the second part, the optimal method in previous simulation was implemented utilizing TMS320C6713 board combined with headphone and the circuit related to the experiment. There were two parts of experiments in hardware, they were different from whether having speech from headphone or not. In the experiment without speech, the results showed the noise reduction more than 15dB in average in single frequency and dual frequency noise, and the result showed the effectiveness of reducing noise in possible reduction frequency range in multi-frequency noise ; the experiment with speech, the results showed more than 10dB in average noise reduction in single frequency and noise reduction around 5dB in average in dual frequency noise, but the result of attenuating noise was not obvious in multi-frequency noise. In conclusion, in all kinds of noise environment, most results showed the algorithm using in hardware not only could reduce unwanted noise but also allowed the desired speech signal to pass through without cancellation and maintain the original speech quality at the same time.
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