The objective of this work is to devise a new way to embed a watermark into digital audio signal. In conventional methods, it is required that the watermark is embedded without noise perception. However, it is difficult to embed the watermark without noise perception. Hence, we propose an embedding method so as to permit a perception of an embedded watermark signal. For watermarked audio signal, high sound quality is needed even if noises are perceived. Therefore, we estimate notes into music data and decide their timbre by musical instrument identification. Furthermore, for improving the sound quality, we embed one bit of watermark into one tone using the corresponding sampled sound for each tone.