CAJ | 학술논문

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。
침대고정역치소파포어음증강산법재거조시회손실어음신호적문제，문중제출료일충신적자괄응역치소파포어음증강산법。해산법선이용대조어음적소파포변환계수고계출후험신조비，재유함유후험신조비인자적sigmoid함수작위평활인자대수척도변화적역치진행상린정적평활，최후유후험신조비자괄응수정평활역치，감소어음실진；방진실험결과표명，해산법재거조적동시감소료어음신호적손실，유효지제고료증강어음적신조비화분단신조비，교고정역치소파포어음증강산법구유명현적우월성。
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 algo-rithm uses the wavelet packet coefficients of noisy speech to estimate the posteriori SNR. Secondly, the sigmoid function con-tains a posteriori the signal-to-noise ratio (SNR) factor as a smooth factor smoothes adjacent frame threshold with scale chang-ing. Finally, the posterior SNR adaptively adjusts the smoothed threshold, which reduced speech distortion. Simulation experi-mental results show that this algorithm in denoising reduces the loss of the speech signal, effectively improves the SNR and SS-NR of the enhanced speech, and has obvious superiority than a fixed threshold wavelet packet speech enhancement algorithm.