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

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

Voice conversion versus speaker verification: an overview

A speaker verification system automatically accepts or rejects a claimed identity of a speaker based on a speech sample. Recently, a major progress was made in speaker verification which leads to mass market adoption, such as in smartphone and in online commerce for user authentication. A major concern when deploying speaker verification technology is whether a system is robust against spoofing attacks. Speaker verification studies provided us a good insight into speaker characterization, which has contributed to the progress of voice conversion technology. Unfortunately, voice conversion has become one of the most easily accessible techniques to carry out spoofing attacks; therefore, presents a threat to speaker verification systems. In this paper, we will briefly introduce the fundamentals of voice conversion and speaker verification technologies. We then give an overview of recent spoofing attack studies under different conditions with a focus on voice conversion spoofing attack. We will also discuss anti-spoofing attack measures for speaker verification.Published versio

Statistical pattern recognition for audio-forensics : empirical investigations on the application scenarios audio steganalysis and microphone forensics

Magdeburg, Univ., Fak. für Informatik, Diss., 2013von Christian Krätze

Vulnerabilities and attack protection in security systems based on biometric recognition

Tesis doctoral inédita. Universidad Autónoma de Madrid, Escuela Politécnica Superior, noviembre de 200

音信号に対する知覚不可能な情報ハイディング技術の研究

本研究では，生理的・知覚的な聴覚特性を考慮した位相情報操作により，ディジタル表現された音信号そのものに様々な情報を知覚されないように隠す，音情報ハイディング技術の確立を目指した．まず，蝸牛遅延に対応する位相と時間変化と検知閾の関係を明らかにし，蝸牛遅延を効果的に制御する方法を実現した．次に，その結果に基づいた知覚不可能で頑健・ブラインド・可逆変換可能な電子音響透かし法を実現した．最後に，応用展開として，AMラジオにおける情報ハイディング法，音声改ざん検出法，フォルマント強調に基づいた電子音響透かしや音声スクランブル法を提案した． : This study aimed to propose a scheme of digital audio/speech information hiding techniques by considering phase controlling based on psychoacoustical and physiological studies for human auditory perception. This study investigated to relationships between phase shifts based on cochlear delay and audibility and then realized methods for effectively controlling phase modulation based on cochlear delay for inaudibility. This study then proposed inaudible, blind, robust, and reversible digital-audio watermarking methods from these investigations. Information hiding for AM radio systems, tampering detection method for speech, speech watermarking based on formant enhancement, and scramble method for speech signal by random-bit shift of quantization were introduced as applications of the proposed scheme.研究種目：基盤研究(B)研究期間：2011～2013課題番号：23300070研究者番号：00343187研究分野：マルチメディア信号処理科研費の分科・細目：情報学・知覚情報処理・知能ロボティク