Audio Watermarking Based on Sinusoidal Amplitude Modulation

A now watermarking system based on amplitude modulation is proposed. Sinusoidal amplitude modulations at relatively low modulation frequencies applied to the neighboring subband signals in opposite phase are used as the carrier of embedded information. The embedded information is encoded in the form of the relative phase differences between the amplitude modulations applied to several groups of sub band signals. Extraction of the amplitude modulations from the watermarked signal is performed by calculating the logarithmic ratio of the amplitude envelopes extracted from the neighboring subband signals. Deterioration of the sound quality resulting from the watermarking is barely detectable because modulation detection interference in the human auditory system and masking in the frequency-domain disturb the perceptual detectability of the additional amplitude modulations