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Quality the Key to Bin Laden Tape

15:53 13 November 02

NewScientist.com news service

A new message claimed to be recorded by Osama bin Laden was broadcast on Arab satellite television on Tuesday. It refers to recent terrorist attacks, including that in Bali, providing the first potential evidence that the Al-Qaeda leader survived the war in Afghanistan.

The US government is extremely keen to determine whether bin Laden is alive, and could orchestrate future acts of terrorism against Western targets. Voice analysis experts say the quality of the recording appears good enough to determine if the recording is genuine, by comparing it with existing audio of the Saudi fugitive.

Steve Cain of Forensic Tape Analysis, a US company specialising in vocal forensics, has been sent snippets of the tape by US television networks. He told New Scientist: "It seems like it is at least clear enough and there's enough amplitude of that unknown speaker's voice that if you had a known sample of bin Laden it would be possible."

But Cain, who has analysed voice recordings in many different languages, says it would be necessary to match syllables and even whole words from the recording with previous audio from radio and television recordings. Key vocal characteristics including frequency and amplitude can then be represented on computer and compared for similarity.

"There is always the possibility of error," adds Tomi Kinnunnen, an expert in computer analysis of speech at the University of Joensuu, Finland. "But if you have a clean sample with little noise, you can quite reliably say [who it is.]"

Sounding sick

The recording was broadcast on the Arab satellite television network Al Jazeera. Representatives at the network who have met bin Laden claim that voice on the tape is his.

Some Western experts also say the recording seems to be genuine. Matsumi Suzuki of Japan Acoustic Lab, in Tokyo, said that the recording seems genuine and that the speaker sounded ill.

The man on the tape praises recent terrorist attacks against Western targets including the bombing of a nightclub in Bali on 12 October, the Moscow hostage siege on 23 October and the attack on a French tanker in Yemen on 6 October. He also mentions bomb attacks in Karachi, Kuwait and Tunisia carried out earlier in 2002.

The man says these attacks were, "merely a reciprocal reaction to what Bush, the modern-day pharaoh, did by murdering our children in Iraq and what Israel, the ally of America, did in bombing houses of the elderly, women and children in Palestine, using American planes."

The recording warns that the US and its allies will face further reprisals if Iraq is attacked. Another audio tape recording recently broadcast is said to have been made by Ayman al-Zawahiri, an Egyptian militant and a close ally of bin Laden.

Will Knight