Controlled Distortion for High Capacity Data-in-Speech Spectrum Steganography

Methods applied to ensure privacy of digital data became essential in many real life applications. Efficient secrecy can be achieved, at least in part, by implementing steganography techniques. In this paper, we present a technique that limits the impact of high data capacity embedding on the quality of stego wideband speech. Our method uses the energy of each frequency bin component to determine the maximum number of bits that can be confined without inducing any noticeable distortion on the cover speech. To guarantee good quality of stego speech, the embedding in the selected frequency components occurs below a well defined distortion level to limit the impact of the hiding on the stego-speech. The algorithm uses multiple parameters that can be adjusted by the sender to render the steganalysis work more challenging. The objective and subjective results show that this approach is robust to noise addition and maintains a very good quality of the cover signal while achieving high hiding capacity.