Voice stress analyses: Science and pseudoscience

Voice stress analyses could be relevant tools to detect deception in many forensic and security contexts. However, today's commercial voice-based lie-detectors are not supported by convincing scientific evidence. In addition to the scientific implausibility of their working principles, the experimental evidence invoked by the sellers is either anecdotal or drawn from methodologically flawed experiments. Nevertheless, criminal investigators, authorities and even some academics appear to be persuaded by the ungrounded claims of the aggressive propaganda from sellers of voice stress analysis gadgets, perhaps further enhanced by the portrays of "cutting-edge voice-analysis technology" in the entertainment industry. Clearly, because there is a serious threat to public justice and security if authorities adopt a naïve "open-minded" attitude towards sham lie-detection devices, this presentation will attempt to draw attention to plausibility and validity issues in connection with the claimed working principles of two commercial voice stress analyzers. The working principles will be discussed from a phonetics and speech analysis perspective and the processes that may lead naïve observers into interpreting as meaningful the spurious results generated by such commercial devices will be examined. Finally, the scope and limitations of using scientific phonetic analyses of voice to detect deception for forensic purposes will be discussed.