Hypnosound

The hypnosound was soundwave that affected the fear centres of the mind. It seems only to affect the weak minded such as Ogrons. Once people chose to believe it was an illusion, they were unaffected by the soundwaves. The strong minded can fight back and resist.

The master created a device that sent out hynosound waves to provoke war between Earth and Draconia in the 26th century on behalf of the Daleks. When Jo heard this sound she saw a Drashig and a Sea Devil. The Humans of Earth saw Draconians attacking their ships and the Draconians saw Humans, when in fact it was actually Ogrons. When the Doctor and his friends were imprisoned on the Ogron home planet, the Doctor used this device on an Ogron to let them escape. The Ogron saw the golden Dalek Supreme and immediately let the Doctor and his friends out of their cells. (DW: Frontier in Space)