The US military has bankrolled early development of a non-lethal microwave weapon that can cause sound inside the target's head. The Mob Excess Deterrent Using Silent Audio ("MEDUSA") is based on a well-known phenomenon, but the link to potential military use has only recently been made. When active, the MEDUSA's microwave beam causes shockwaves inside its targets' skulls which can be detected by the ears. A series of microwave pulses can also be created to produce recognisable sounds. The MEDUSA's advantage lies in that the generated sound originates from within the skull, and cannot be blocked out by conventional means such as earplugs. Depending on the intensity of the beam, the effect can range from annoyance to incapacitation. Conversely, personnel situated outside the MEDUSA's beam will be completely unaffected. In addition to potential applications on the battlefield and in crowd control, the technology behind the MEDUSA may also be of assistance to people with outer ear problems that impair their normal hearing.MEDUSA involves a microwave auditory effect "loud" enough to cause discomfort or even incapacitation. Sadovnik says that normal audio safety limits do not apply since the sound does not enter through the eardrums.
"The repel effect is a combination of loudness and the irritation factor," he says. "You can't block it out."
Sadovnik says the device will work thanks to a new reconfigurable antenna developed by colleague Vladimir Manasson. It steers the beam electronically, making it possible to flip from a broad to a narrow beam, or aim at multiple targets simultaneously.
Sadovnik says the technology could have non-military applications. Birds seem to be highly sensitive to microwave audio, he says, so it might be used to scare away unwanted flocks.
Sadovnik has also experimented with transmitting microwave audio to people with outer ear problems that impair their normal hearing.
