11/19/2002: Bin Laden Tape Is Genuine, U.S. Experts Conclude

United States intelligence officials have concluded that a recently recorded audiotape that was broadcast on an Arab television network last week is genuine and contains the voice of Osama bin Laden, apparently ending months of debate in the government over whether the elusive terrorist leader is still alive. [New York Times]

11/30/2002: Swiss scientists: "The recording is a fake"

Scientists in Switzerland say they are almost certain that an audio tape attributed to Osama bin Laden is a fake. ... 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 Hervé Bourlard, the institute's director, told the Guardian yesterday. [Guardian]

12/2/2003: Swiss Scientists: "Oops. We won't verify other tapes"

Swiss researchers who last November analysed a tape attributed to Osama bin Laden say they won’t be scrutinising the latest recording broadcast by the Arabic television network, Al-Jazeera. The Swiss analysts said the previous tape was almost certainly faked, despite US claims to the contrary. The Dalle Molle Institute for Perceptual Artificial Intelligence (Idiap) in Martigny told swissinfo on Wednesday that it had no intention of analysing the latest tape. [swissinfo]