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EMF Study
(Database last updated on Aug 8, 2020)

ID Number 693
Study Type In Vivo
Model 918, 2450 MHz (PW) exposure to animals and analysis of microwave hearing

Rats, Guinea pigs, and cats were exposed to 918 and 2450 MHz (PW-30 pps, 10-500 usecond pulse duration [10-500 Hz]) microwaves to produce microwave hearing. The average absorbed energy power density per pulse was 6-180 mJ/kg. The threshold for MW hearing correlated with the energy per pulse for short pulses (< 30 useconds) and with the peak power for longer pulses (30-500 useconds), and was found to be approximately 16 mJ/kg to the head in humans, guinea pigs, rats, and cats using microwaves with pulse widths of < 30 microseconds. Analysis of brain-stem evoked response (BER) during exposure showed the MW hearing effect to be dependent upon an intact cochlea but not affected by blocking the external ear, middle ear damping, or middle ear destruction. Stimulation of the eighth cranial nerve, medial geniculate nucleus, and primary auditory cortex was recorded in evoked auditory response studies. Cochlear microphonic osilations produced by exposure were related to the size of the skull, 38 Hz for cats, 50 Hz for guinea pigs. The authors suggest microwave hearing is due to induction of high frequency vibrations in the head by transient thermal expansion of tissue due to the rapid absorption of pulsed microwave energy.

Findings Effects (only at thermal levels)
Status Completed With Publication
Principal Investigator Motorola Labs, Ft. Lauderdale FL, USA
Funding Agency NIH, USA
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