“The microwave auditory effect is a real stretch. It is a biologically trivial effect due to thermally generated vibrations in the head,” University of Pennsylvania bioengineer Kenneth Foster, who documented the mechanism for the effect in 1974, told BuzzFeed News.

“It takes strong microwave pulses to generate barely detectable sounds in the head, and the sound levels in the head are many orders of magnitude below anything that is reasonably anticipated to be hazardous.”

The clicks are so quiet that in order for participants to hear them in 1970s experiments in a sound chamber at the University of Washington, researchers had to to turn off the computers in the adjacent room, microwave expert Chung-Kwang Chou, who heads an Institute of Electrical and Electronics Engineers (IEEE) committee on the health effects of microwaves, told BuzzFeed News.