一种新的自适应阈值小波包语音增强算法

A New Adaptive Threshold of Wavelet Packet for Speech Enhancement Algorithm

针对固定阈值小波包语音增强算法在去噪时会损失语音信号的问题,文中提出了一种新的自适应阈值小波包语音增强算法。该算法先利用带噪语音的小波包变换系数估计出后验信噪比,再由含有后验信噪比因子的sigmoid函数作为平滑因子对随尺度变化的阈值进行相邻帧的平滑,最后由后验信噪比自适应修正平滑阈值,减少语音失真;仿真实验结果表明,该算法在去噪的同时减少了语音信号的损失,有效地提高了增强语音的信噪比和分段信噪比,较固定阈值小波包语音增强算法具有明显的优越性。

Aiming at the problem of the fixed threshold wavelet packet speech enhancement algorithm loses the speech signal in denoising,this paper proposed a new adaptive threshold of wavelet packet for speech enhancement algorithm. Firstly,the algorithm uses the wavelet packet coefficients of noisy speech to estimate the posteriori SNR. Secondly,the sigmoid function contains a posteriori the signal-to-noise ratio(SNR) factor as a smooth factor smoothes adjacent frame threshold with scale changing. Finally,the posterior SNR adaptively adjusts the smoothed threshold,which reduced speech distortion. Simulation experimental results show that this algorithm in denoising reduces the loss of the speech signal,effectively improves the SNR and SSNR of the enhanced speech,and has obvious superiority than a fixed threshold wavelet packet speech enhancement algorithm.