In this paper, we propose a new watermarking method based on modification of sound pressure level between microphones. We focus on two characteristics of sound source. One is location of a dominant sound source will be maintained even if signal processing like MP3 compression is performed. Two is deterioration of sound quality is imperceptible even if location of a dominant sound source is modified slightly. By using these characteristics, it is confirmed that we can embed the watermark information with high sound quality and high robustness to MP3 compression. Moreover, we confirm the validity of proposed method using music data having sparse representation. © 2013 IEEE.