CAJ | 학술논문

为了有效抑制语音信号传输中引入的噪声，提出一种基于经验模态分解（EMD）的小波阈值去噪方法。针对传统小波阈值去噪方法中，硬阈值函数的不连续性和软阈值函数中估计小波系数与分解小波系数之间的恒定偏差问题，构造了一种高阶可导的新阈值函数。该函数通过调整双参数实现函数形状的灵活变化，以接近理想小波系数。将该去噪方法应用于实际语音信号进行去噪处理。实验结果表明，在信噪比较低时，相比单纯采用小波阈值方法和EMD尺度滤波方法，采用该方法对语音信号进行处理能提高信噪比，较好地抑制噪声的干扰，可用于噪声环境下语音识别系统的前端处理，提高系统的识别效果。
위료유효억제어음신호전수중인입적조성，제출일충기우경험모태분해（EMD）적소파역치거조방법。침대전통소파역치거조방법중，경역치함수적불련속성화연역치함수중고계소파계수여분해소파계수지간적항정편차문제，구조료일충고계가도적신역치함수。해함수통과조정쌍삼수실현함수형상적령활변화，이접근이상소파계수。장해거조방법응용우실제어음신호진행거조처리。실험결과표명，재신조비교저시，상비단순채용소파역치방법화EMD척도려파방법，채용해방법대어음신호진행처리능제고신조비，교호지억제조성적간우，가용우조성배경하어음식별계통적전단처리，제고계통적식별효과。
To restrain the noise introduced during the transmission of speech signal effectively,a method based on EMD and wavelet threshold de-noising was proposed.Moreover,aiming at the problems of the discontinuance of hard threshold function and the constant deviation between estimated wavelet coefficients and decomposition wavelet coefficients in the soft threshold function in conventional wavelet threshold de-noising,a new kind of high order derivable threshold function was constructed, which could change the shape of the function flexiblely by adjusting dual parameter to get close to the ideal wavelet coefficients. The EMD-based wavelet threshold method was applied to process actual speech signal.Simulation results showed that the pro-posed method increased output SNR and restrained the noise better,compared with speech de-noising based on wavelet and EMD scale filter in the case of low SNR,and could be used in the front of speech recognition system in noisy environment to improve the accuracy of the recognition results.