A semi-fragile watermarking algorithm for copyright protection and content authentication is proposed in this paper. The features of the proposed algorithm are as follows: 1) The watermark depth can be adaptively adjusted according to local audio character, enhanced the robustness of digital audio watermark ; 2) The copyright protection and content authentication for digital audio can be utilized simultaneously. The proposed algorithm can locate the tampered region. Experimental results show that the semi-fragile audio watermarking algorithm is robust against various signals processing such as low pass filtering, loss compression, and re-sampling. In addition, the proposed scheme can detect effectively the tampered regions.