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Few scientists believe that ultralow frequency acoustic weapons will work
(This Week, 20 March, p 17),
but Maxwell Technologies of San Diego is patenting
one nonetheless. Its device works across a wide range of frequencies and is
highly directional. It is designed to control hostile crowds or disable hostage
takers (WO 99/17071). The company says it can cause injury to people up to 100
metres away. Cylinders supply bursts of explosive gases that are detonated by
100-kilovolt sparks. Maxwell claims it causes pain at sound levels of 145
decibels, ruptures eardrums at 185 dB, leads to pulmonary injury at 200 dB and
death at 220 dB.