Distortion product otoacoustic emissions (DPOAEs) were measured within transmission pauses, i.e. between electromagnetic field signal pulses. Thus, an undistorted measurement of DPOAEs was possible during exposure.
|Distance between exposed object and exposure source||5 cm|
|Exposure room||Sound-proof, electromagnetically shielded room (6.5 x 2.8 x 3.0 m) with walls, floor, and ceiling covered by RF-absorbing materials. Nothing but the mobile phone dummy and the subject lying quietly on a plastic camp bed were in the room.|
|Additional info||For each subject, each DPOA measurement was repeated 8 times, applying EMF and sham exposure in alternating order (single-blind). In total, each subject underwent 12 tests each test lasting about 24 min. Testing was broken up into multiple sessions. The measuring procedure was the same for sham as for EMF exposure but the EMF was switched off.|
No significant change in the DPOAE level in response to the electromagnetic field exposure was revealed. However, when undesired side effects on DPOAEs were compensated, in some subjects an extremely small electromagnetic field-exposure-correlated change in the DPOAE level (< 1 dB) was found. In view of the very large dynamic range of hearing in humans (120 dB), it is suggested that this observation is physiologically irrelevant.