Vladimir Gavreau's Fan Blade

Origin
Vladimir Gavreau experimented on the effects of sound waves, specifically how infrasound altered biological systems. His interest in infrasonic waves first came about in his lab during the 1960s, when he and his lab assistants experienced pain in the ear drums and shaking lab equipment, but no audible sound was picked up on his microphones. He concluded that it was infrasound and got to work preparing tests in the labs.

Effects
When spun at just the right speed generates infrasound waves. Even though they're inaudible, the waves are harmful to anyone whose ears aren't protected from them, inducing bouts of nausea, headaches, & dizziness. The effects are magnified depending on the acoustics of the environment in which the fan is used; in the right setting, the infrasound can even be lethal.