Abstract: Audio steganography methods and apparatus using cepstral domain techniques to make embedded data in audio signals less perceivable. One approach defines a set of frames for a host audio signal, and, for each frame, determines a plurality of masked frequencies as spectral points with power level below a masking threshold for the frame. The two most commonly occurring masked frequencies f1 and f2 in the set of frames are selected, and a cepstrum of each frame is modified to produce complementary changes of the spectrum at f1 and f2 to correspond to a desired bit value. Another aspect of the invention involves determining a masking threshold for a frame, determining masked frequencies within the frame having a power level below threshold, obtaining a cepstrum of a sinusoid at a selected masked frequency, and modifying the frame by an offset to correspond to an embedded data value, the offset derived from the cepstrum.

Abstract: Method for embedding a covert message within a digital audio signal. The existence of the covert message is undetectable and the information content of the covert message can be further rendered unascertainable. Covert message data is embedded within a digital audio signal on an audio frame-by-audio frame basis. Covert message data is embedded either at a rate of one bit per frame or two bits per frame. The invention has uses including but not limited to watermarking digital audio signals, hiding data within a digital audio signal, increasing the channel capacity of a communications channel by placing multiple messages within each other, and generally increasing message robustness.

Abstract: Method and apparatus for embedding binary data in audio signals. The magnitude of the power spectrum at the perceptual holes of each frame of a host speech utterance, may be altered so as to embed digital data. The phase spectrum at perceptually masked spectral points of each frame of a host speech utterance, may also be altered so as to embed digital data.

Abstract: Method for embedding a covert message within a digital audio signal. The existence of the covert message is undetectable and the information content of the covert message can be further rendered unascertainable. Covert message data is embedded within a digital audio signal on an audio frame-by-audio frame basis. Covert message data is embedded either at a rate of one bit per frame or two bits per frame. The invention has uses including but not limited to watermarking digital audio signals, hiding data within a digital audio signal, increasing the channel capacity of a communications channel by placing multiple messages within each other, and generally increasing message robustness.

Abstract: Method and apparatus for embedding binary data in audio signals. The magnitude of the power spectrum at the perceptual holes of each frame of a host speech utterance, may be altered so as to embed digital data. The phase spectrum at perceptually masked spectral points of each frame of a host speech utterance, may also be altered so as to embed digital data.