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 for improving speaker identification by determining usable speech. Degraded speech is preprocessed in a speaker identification (SID) process to produce SID usable and SID unusable segments. Features are extracted and analyzed so as to produce a matrix of optimum classifiers for the detection of SID usable and SID unusable speech segments. Optimum classifiers possess a minimum distance from a speaker model. A decision tree based upon fixed thresholds indicates the presence of a speech feature in a given speech segment. Following preprocessing, degraded speech is measured in one or more time, frequency, cepstral or SID usable/unusable domains. The results of the measurements are multiplied by a weighting factor whose value is proportional to the reliability of the corresponding time, frequency, or cepstral measurements performed. The measurements are fused as information, and usable speech segments are extracted for further processing.