Data hiding in speech using phase coding

The human auditory system is insensitive to phase information of the speech signal. By taking advantage of this fact data such as the transcript, some keywords, and copyright information can be embedded into the speech signal by altering the phase in a prede ned manner. In this paper, an all-pass ltering based data embedding scheme is developed for speech signals. Since all-pass lters modify only the phase without e ecting the magnitude response they are employed to di use data into the speech signal by ltering di erent portions of the speech signal with di erent all-pass lters. The embedded data can be retrieved by tracking the zeros of the all-pass lters.