This paper presents an adaptive and blind digital audio watermarking algorithm based on the Walsh-Hadamard transform（WHT） and signal-to-noise ratio（SNR）.A new observation on the adaptive problem of embedding strength factor for additive watermark is uncovered.To preserve the audio fidelity

the proposed algorithm utilizes SNR to adjust the embedding strength factor adaptively and the watermark bits are embedded into the WHT low frequency coefficients.When detected

the watermark can be extracted without the help from the origin digital audio signal.Simulation results show that the proposed algorithm can not only guarantee good imperceptibility

but also be robust against common signal processing such as noise addition

low-pass filtering

re-sampling

re-quantization

and MP3 compression.