Microwave Auditory Effect—A Comparison of Some Possible Transduction Mechanisms

When human subjects are irradiated with pulse modulated microwave energy they report the perception of a sound that appears to originate from within or slightly behing the head. Three of the possible mechanisms are examined using first order mathematical approximations and several simplifying assumptions. The results show that while all three (radiation pressure, strictive force and thermal expansion) are capable of producing the phenomenon, the stress resulting from thermal expansion may be so great that it masks the effect of the others completely.