中文摘要：

基于AAC比特流,提出了一种压缩域音频Hiss噪声抑制方法。该方法的输入为含噪音频的AAC比特流,输出为增强音频的AAC比特流。首先,利用修正的绝对中值标准差（MMAD,modified median absolute deviation）估计Hiss噪声,其次,利用修正的离散傅里叶变换（MDFT,modified discrete Fourier transform）计算听觉掩蔽阈值参数,最后,根据参数软阈值方法得到增强的AAC比特流,并用于AAC解码器得到最终的增强音频信号。主观和客观测试结果表明,所提出的方法能有效去除AAC解码音频信号中的Hiss噪声,其性能明显优于现有的几种Hiss噪声消除方法。

英文摘要：

A hiss noise reduction method used for audio signals based on AAC bit-stream in compressed domain was proposed. The input was AAC bit-stream derived from noisy audio signals, and the output was the enhanced AAC bit-stream used for decoder. First, Hiss noise was estimated by modified median absolute deviation （MMAD）. Second, the auditory masking threshold and the masking parameters were calculated by modified discrete Flourier transform （MDFT）. Finally, the parametric soft-thresholding method was employed to obtain the enhanced AAC bit-stream which was used to get the enhanced audio signals at AAC decoder. The objective and subjective quality testing results indicate that the proposed algorithm can effectively remove the Hiss noise derived from AAC bit-stream of audio signals and ob- viously outperforms the existing hiss noise reduction methods.