According to Frey, the induced sounds were described as "a buzz, clicking, hiss, or knocking, depending on several transmitter parameters, i.e., pulse width and pulse-repetition rate".
By changing transmitter parameters, Frey was able to induce the "perception of severe buffeting of the head, without such apparent vestibular symptoms as dizziness or nausea".
The cause is thought to be thermoelastic expansion of portions of auditory apparatus, and the generally accepted mechanism is rapid (but minuscule, in the range of 10−5 °C) heating of brain by each pulse, and the resulting pressure wave traveling through the skull to the cochlea.
[7] So while threshold levels of for the microwave audio effect of 267mW/cm² for 1.3GHz and 5000mW/cm² 2.9GHz, respectively, were reported by Frey in 1961, for the peak amplitude (providing the pops) and would only give an average (sustained) power density of only 0.4mW/cm² and 2mW/cm² respectively[7] similar to current cellphones.
[8] In 2003–04, WaveBand Corp. had a contract from the U.S. Navy for the design of an MAE system they called MEDUSA (Mob Excess Deterrent Using Silent Audio) that was intended to temporarily incapacitate personnel through remote application.
According to former professor at the University of Washington Bill Guy, "There's a misunderstanding by the public and even some scientists about this auditory effect," and "there couldn't possibly be a hazard from the sound, because the heat would get you first".
[20][21] Psychologists have identified many examples of people reporting 'mind control experiences' (MCEs) on self-published web pages that are "highly likely to be influenced by delusional beliefs".