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Speaker identification is a widely used technique in several security
systems. In remote access systems, speaker utterances are recoded and
communicated through a communication channel to a receiver that performs the
identification process. Speaker identification is based on characterizing each
speaker with a set of features extracted from his or her utterance. Extracting the
features from a clean speech signal guarantees the high success rate in the identification
process. In real cases, a clean speech is not available for feature extraction
due to channel degradations, background noise, or interfering audio signals. As a
result, there is a need for speech enhancement, deconvolution, and separation
algorithms to solve the problem of speaker identification in the presence of
impairments. Another important issue, which deserves consideration, is how to
enhance the security of a speaker identification system. This can be accomplished
by watermark embedding in the clean speech signals at the transmitter. If this
watermark is extracted correctly at the receiver, it can be used to ensure the correct
speaker identification. Another means of security enhancement is the encryption
of speech at the transmitter. Speech encryption prevents eavesdroppers from
getting the speech signals that will be used for feature extraction to avoid any
unauthorized access to the system by synthesis trials. Multilevels of security can be
achieved by implementing both watermarking and encryption at the transmitter.
The watermarking and encryption algorithms need to be robust to speech enhancement,
and deconvolution algorithms to achieve the required degree of security and
the highest possible speaker identification rates. This book provides for the first
time a comprehensive literature review on how to improve the performance of
speaker identification systems in noisy environments, by combining different
feature extraction techniques with speech enhancement, deconvolution, separation,
watermarking, and/or encryption.
The author covers the fundamentals of both information and communication security including current developments in some of the most critical areas of automatic speech recognition. Included are topics on speech watermarking, speech encryption, steganography, multilevel security systems comprising speaker identification, real transmission of watermarked or encrypted speech signals, and more. The book is especially useful for information security specialist, government security analysts, speech development professionals, and for individuals involved in the study and research of speech recognition at advanced levels. |
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