Mechanisms and physiologic significance of microwave action on the auditory system
Studies conducted by the authors and their coworkers on the mechanisms and physiologic significance of radiofrequency hearing effects are reviewed. Results of these studies demonstrate that thermoelastic expansion of fluids and structures within the inner ear is the main mechanism by which auditory stimuli are produced by microwave pulses; the frequency spectra of these stimuli are indistinguishable from the spectra of rectangular pulses with the same durations as the microwave pulses; exposure to continuous-wave (CW) microwave radiation evokes an increase in the metabolic activities of nuclei in the ascending auditory pathway and also decreases the latency and increases the magnitude of brainstem-evoked responses produced by acoustic clicks; and the mechanism of the effects of CW microwave radiation on the auditory system is intracochlear heating. The significance of these findings is discussed in terms of potential applications of microwave stimuli in basic research on the auditory system and in terms of interpreting the results of past studies that demonstrate behavioral sensitivity to CW microwave fields.
