Saturday, November 30th, 2002
Brian Whitaker, The Guardian
Saturday November 30 2002
Scientists in Switzerland say they are almost certain that a recent audio tape attributed to Osama bin Laden is a fake.
The tape, delivered to the Arab satellite television channel al-Jazeera earlier this month, appeared to provide the first concrete evidence that Bin Laden is still alive because it mentioned recent attacks on western targets.
American experts initially concluded that the voice on the tape was probably Bin Laden, though it is unlikely ever to be fully authenticated because of the recording’s poor quality.
The Swiss findings conflict with other research published by the French news magazine L’Express last week.
In that study, Bernard Gautheron, director of the phonetic testing laboratory at the Institute of Linguistics and Phonetics in Paris, concluded there was a “very strong probability” that the al-Jazeera tape was genuine.
But researchers at the Dalle Molle Institute for Perceptual Artificial Intelligence, in Lausanne, believe the message was recorded by an impostor.
In a study commissioned by France 2 television, researchers built a computer model of Bin Laden’s voice, based on an hour of genuine recordings.
Using voice recognition systems being developed for banking security, they tested the model against 20 known recordings of Bin Laden. The system correctly identified his voice in 19 of them.
This meant there was only a 5% risk of error in their conclusion that the latest tape is a fake, Professor HervÃƒÆ’Ã‚Â© Bourlard, the institute’s director, told the Guardian yesterday. “It’s an automatic system but it’s very sensitive,” he said. “It picks up things the human ear doesn’t pick up.”
He agreed that the sound quality of the recent tape was poor but added: “Many of our 20 [test] recordings were also of poor quality. Some were very good, some very bad, but our results were all positive except in one case.”
Prof Bourlard, a voice recognition expert, is the author or joint author of 150 research papers and two books, and has worked extensively with the International Computer Science Institute at Berkeley, California.