Abstract: A digital watermark embedding apparatus generates an echo signal, which is delayed a time period corresponding to digital watermark information to be embedded with respect to each tone signal that forms an original audio signal, and inserts the generated echo signal in the original audio signal by spreading the echo signal on the time axis, thus outputting a watermarked audio signal. A digital watermark detection apparatus despreads echo signals contained in the watermarked audio signal on the time axis, and extracts digital watermark information from the generation time of the despread echo signal contained in the watermarked audio signal.

Abstract: A digital watermark embedding apparatus generates an echo signal, which is delayed a time period corresponding to digital watermark information to be embedded with respect to each tone signal that forms an original audio signal, and inserts the generated echo signal in the original audio signal by spreading the echo signal on the time axis, thus outputting a watermarked audio signal. A digital watermark detection apparatus despreads echo signals contained in the watermarked audio signal on the time axis, and extracts digital watermark information from the generation time of the despread echo signal contained in the watermarked audio signal.

Abstract: When a music signal undergoes sinusoidal phase modulation using a second-order all-pass filter, if the period of modulation is equal to or lower than several hundreds Hz, that modulation is not perceived by a human being. Watermark information is embedded using this phase modulation as a carrier, thus implementing digital watermarking. On the detector, since a model of the all-pass filter used in phase modulation is known, the filter is estimated by ARMA model parameter estimation, and the dynamic characteristics of phase modulation are estimated from its temporal change.