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Mathematical Problems in Engineering
Volume 2017, Article ID 3597695, 9 pages
Research Article

Semifragile Speech Watermarking Based on Least Significant Bit Replacement of Line Spectral Frequencies

1Department of Computer Engineering, Islamic Azad University, Safadasht Branch, Tehran, Iran
2Cybersecurity Laboratory, Wireless Innovation and Security Research Unit, National Electronics and Computer Technology Center (NECTEC), 112 Phahonyothin Road, Khlong Nueng, Khlong Luang District, Pathumthani 12120, Thailand
3Department of Electronics Engineering, Universidad Autónoma de Zacatecas, 98000 Zacatecas, ZAC, Mexico

Correspondence should be addressed to Mohammad Ali Nematollahi; moc.liamg@eaugnitupmocneerg

Received 19 July 2016; Revised 24 November 2016; Accepted 19 December 2016; Published 10 January 2017

Academic Editor: Xinkai Chen

Copyright © 2017 Mohammad Ali Nematollahi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


There are various techniques for speech watermarking based on modifying the linear prediction coefficients (LPCs); however, the estimated and modified LPCs vary from each other even without attacks. Because line spectral frequency (LSF) has less sensitivity to watermarking than LPC, watermark bits are embedded into the maximum number of LSFs by applying the least significant bit replacement (LSBR) method. To reduce the differences between estimated and modified LPCs, a checking loop is added to minimize the watermark extraction error. Experimental results show that the proposed semifragile speech watermarking method can provide high imperceptibility and that any manipulation of the watermark signal destroys the watermark bits since manipulation changes it to a random stream of bits.