Using phonetics to catch criminals

Picture a courtroom drama: a man with links to the local Narcotics Control Board is up on charges of drug-dealing.  The prosecution's main piece of evidence: a tape recording in which the accused is speaking to a suspected merchant about a sale. The defence says he made the recording as part of a set-up, trying to get the merchant to say something incriminating. The prosecution believes the recording is about a genuine drug deal. Who can tell the difference? A group of linguists from a local university, who do an analysis of the tape and find that the recording is not part of a stage-managed sting operation. The Narcotics Control Board man is found guilty, and sentenced to 15 years with hard labour.

This isn't the script for a Hollywood blockbuster, but the very real story of a celebrated criminal trial in Ghana, which forensic linguist Paul Foulkes will be talking about in his keynote address on the last day of Interactions and Interfaces, a conference which the Rhodes Linguistics department will be hosting next week. Foulkes is a professor at the University of York, and also a consultant for J.P. French Associates, the UK's longest-established forensic speech laboratory. He has been involved in about 150 cases, working both for the prosecution and defence, and has even delivered training seminars to the FBI and United States Secret Service.

Foulkes will focus on two main ways in which forensic linguistics is being used in solving crimes. The first is speaker profiling. In cases like kidnappings where there is a voice recording of the perpetrators, but they have not yet been identified, forensic linguistics can be used to find out what area or social class they might come from, what ethnic group they could be a part of, and what other languages they might speak.

Even more common is speaker comparison, where a voice from a recording taken during a crime is matched up with recordings from various suspects taken from concealed recording devices, voice messages or hoax calls to emergency numbers. This type of analysis can identify criminals and form the clinching piece of evidence in a trial like the one described above.

Foulkes writes that “Well known cases that have involved forensic speech analysis include Watergate, the Yorkshire Ripper enquiry, the UN war crimes tribunal of former President Milosevic, and the ‘Who wants to be a millionaire?’ fraud trial.”

His keynote address will be held from 9:00 to 10:00am in Eden Grove Blue on Wednesday 29 June. For more information on Interactions and Interfaces, visit the conference website at http://www.linguisticsconference2011.co.za/, or contact Sally Hunt at s.hunt@ru.ac.za or 046 603 8105.