The knees buckle, the brain aches, the stomach turns. And suddenly, nobody feels like protesting anymore. Witnesses describe a minute-long blast of sound emanating from a white Israeli military vehicle. Within seconds, protestors began falling to their knees, unable to maintain their balance. An Israeli military source, speaking on the customary condition of anonymity, confirmed the existence of the Scream. The intention is to disperse crowds with sound pulses that create nausea and dizziness," the Israel Defence Force spokesperson told the Toronto Star. The IDF is saying little about the science behind the Scream, citing classified information. But the technology is believed to be similar to the LRAD - Long-Range Acoustic Device - used by U.S. forces in Iraq as a means of crowd control. Hillel Pratt, a professor of neurobiology ... likens the effect of such technologies to simulated seasickness. "It doesn't necessarily have to be a loud sound. The combination of low frequencies at high intensities, for example, can create discrepancies in the inputs to the brain," said Pratt. Arik Asherman, a leader of Rabbis For Human Rights, was cautiously optimistic the Scream could make a positive difference. But Asherman said Israeli officials would be wise to use the Scream sparingly. "We need to remind ourselves the problem is not the demonstrations, but what the demonstrations are about," he said. "If this makes it any more difficult for Palestinians to express themselves in a non-violent way, that is problematic. The best way to disperse demonstrations is to deal with the actual issues.