Microwave hearing: The response of single auditory neurons in the cat to pulsed microwave radiation

Abstract

Inferences regarding the mechanism of “microwave hearing” heretofore have been based upon theoretical studies, reports of human observers, animal behavioral experiments, and the recording of auditory field potentials. To gain more insight into the phenomenon we have examined the effect of pulsed microwave radiation (MWR) at 915 MHz on single auditory neurons in the cat. The responses to pulsed acoustic stimuli (“clicks”) and to pulsed MWR were compared by means of post‐stimulus time histograms. Although the response to MWR was dependent upon parameters of the pulse of incident MWR, it was independent of the averaged rate of energy absorption. Threshold effects were observed at an energy dose as low as 4 μJ/g per pulse. Auditory units with characteristic frequencies (CFs) below 1.2 kHz appeared to be more responsive to pulsed MWR than were units with higher CFs. Many neurons demonstrated a response to pulsed MWR that was similar to the response to acoustic clicks, which may provide a means by which to define the acoustic equivalent of MWR. Our results support the view that microwave hearing is mediated, at least in part, by an electromechanical interaction that is initiated distal to the cochlea.