To improve the imperceptibility without decreasing the steganographic capacity when steganography by a modification to an audio is carried out, this paper proposes an optimal matching path algorithm to reduce the modification to achieve it. A steganography operation unit is defined, which is composed of every N consecutive audio frames and each frame includes M LPC parameters. All these parameters in the same steganography operation unit will form an M × N matrix. A traversal path is a sequence of all these parameters in the matrix. Each parameter in the matrix will be converted into a one-bit binary digit based on two subcodebooks divided by the complementary neighbor vertex (CNV) method. Thus, every traversal path will have a corresponding binary string named PathBinStr. Steganography is performed by computing the Hamming distance between the binary secret and the corresponding PathBinStr and selecting the traversal path with minimal hamming distance expected value to hide the secret via the CNV embedding method. The experimental results show that the proposed steganography algorithm has better performance in audio quality and the modified bit rate decreases from 50 to 37.4% when only 6 traversal paths are predefined, and its processing time can satisfy the real-time requirement of VoIP services. Also, it does not change the audio size, and the theoretical analysis and experiments show its undetectability is good.

为了在通过修改音频进行隐写时，在不降低隐写容量的情况下提高不可感知性，本文提出了一种优化匹配路径算法来减少修改来实现它。定义了一个隐写运算单元，由每N个连续的音频帧组成，每帧包含M个LPC参数。所有这些参数在同一个隐写运算单元中将形成一个M  ×  N矩阵。遍历路径是矩阵中所有这些参数的序列。矩阵中的每个参数将基于两个子码本通过互补邻居顶点（CNV）方法划分为一位二进制数字。因此，每个遍历路径都会有一个对应的二进制字符串，名为 PathBinStr。隐写术是通过计算二进制秘密与对应的 PathBinStr 之间的汉明距离，并通过 CNV 嵌入方法选择具有最小汉明距离期望值的遍历路径来隐藏秘密来执行的。实验结果表明，当仅预定义6条遍历路径时，所提出的隐写算法在音频质量上具有更好的性能，修改后的比特率从50%降低到37.4%，其处理时间能够满足VoIP业务的实时性要求。