Proc. SPIE. 5306, Security, Steganography, and Watermarking of Multimedia Contents VI
KEYWORDS: Signal to noise ratio, Detection and tracking algorithms, Digital filtering, Linear filtering, Digital watermarking, Computer programming, Analog electronics, Electronic filtering, Neodymium, Forward error correction
A speech production procedure can be divided into three parts, namely the glottal source, articulation and
radiation, respectively. We propose a watermarking method for speech by manipulating the articulation in the
process of speech production. We apply our method to CS-ACELP(G.729 standard), which is the ITU-T
approved recommendation. It provides a low bit rate 8 kb/s speech coding algorithm with wire/line quality. The
watermarked vocal tract model is expressed by codebooks made by LSP(Line Spectrum Pair) parameters. The
codebook vectors replace some of the extracted LSP. Speech is synthesized using replaced LSP. We generate a
couple of codebooks using a unique method to modify the LSP of the spectrum envelope. Shortening the width
of the LSPs creates one watermarked codebook, and the second codebook is created by stretching the LSP of
both sides of each formant. There are ten LSP dimensions in each voice frame of the CS-ACELP decoder. In the
detecting process, the weighted Euclidean distance(WED) between the watermarked codebooks and the
extracted LSP will be calculated. Whether the watermark is embedded will be judged by utilizing the calculated
WED. Evaluation tests on detection accuracy will be discussed with simulation results.
A speech production model can be ivided into three parts, namely the glottal source, articulation and radiation, respectively. Some digital watermarking methods for speech that have been proposed are based on modifying quantized values or parameters of a coding scheme. In this paper, we propose a new watermarking method for speech by manipulating the articulaton in the process of speech production. The proposed method is performed by modeling a quasi vocal tract model equivalent to the speech production process. The watermarked vocal tract model is expressed by codebooks made by LSP(Line Spectrum Pair) parameters. The procedure of watermark for speech is as follows; 1) LSPs are extracted from the speech. 2) Some of the extracted LSPs are replaced by the codebook vectors. 3) Speech is synthesized using replaced LSPs. In the process above, watermarks are embedded indirectly into the speech. Evaluation tests on speech quality and accuracy of the proposed method will be discussed with simulation results.