A US company claims it is ready to build a microwave ray gun able to beam sounds directly into people's heads.

A company plans to create a gun that takes down transgressors with only sound.

(Getty/ABC News)

The device – dubbed MEDUSA (Mob Excess Deterrent Using Silent Audio) – exploits the microwave audio effect, in which short microwave pulses rapidly heat tissue, causing a shockwave inside the skull that can be detected by the ears. A series of pulses can be transmitted to produce recognisable sounds.

The device is aimed for military or crowd-control applications, but may have other uses.

Lev Sadovnik of the Sierra Nevada Corporation in the US is working on the system, having started work on a US navy research contract. The navy's report states that the effect was shown to be effective.

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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."