ID Number		1436
Study Type		Human / Provocation
Model		900 MHz (GSM-like) exposure to humans and analysis of otoacoustic emissions
Details		Human volunteers with normal hearing (n = 28, mean age 26.9 yrs) were exposed to 900 MHz (GSM-like) RF at an SAR of 0.1 W/kg during administration of test tones and examined for distortion product otoacoustic emissions (DPOAE), a measure of hearing function. Testing was done with the subjects lying down and RF exposure performed using a monopole antenna mounted on a dummy mobile phone. Because the standard GSM protocol 4.034 pulses per second caused distortion in the electro-acoustic transducers used for DPOAE measurements, the period between pulses was lengthened to 24.204 msec (pulse width remained the same at 0.5763 msec). The order of RF and sham exposure was administered in alternating order among the subjects, each acting as a self control. The authors report small but significant exposure related changes in DPOAE (average difference in weighted DPOAE = -0.0049 +/- 1.0353 dB). In follow up analysis, some subjects showed RF / sham differences of greater than 0.25 dB, but the effect was not consistent over all subjects or in repeated tests in any single subject. There was no consistent difference between different auditory test tone levels or frequencies. The authors conclude that since the dynamic range of hearing in humans is greater than 120 dB, the observed changes in DPOAE at tenths of a dB are probably not physiologically relevant.
Findings		No Effects
Status		Completed With Publication
Principal Investigator		Technical University, Munich, Germany
Funding Agency		Private/Instit.
Country		GERMANY
References		Janssen, T et al. J Acoust Soc Am, (2005) 117:1241-1247
Comments		The study was performed single blind (subjects were blinded but investigators were not)