この研究は、GSM（移動体通信用グローバルシステム）携帯電話の電磁界（EMF）が外有毛細胞（OHC）に及ぼす影響を、歪成分耳音響放射（DPOAE）を用いて調べた。このボランティア実験には、28人の正常聴力（4 kHz付近）を有する被験者が参加した。DPOAE測定は、ばく露中（すなわち連続的なGSM信号パルスとパルスの間に）、および擬似ばく露（EMFなし）中に実施された。信頼性の高いDPOAE測定のために、900 MHz GSMに似た信号が使用された。それにより、送信停止時間は4.034ミリ秒（GSM標準）から24.204ミリ秒に増加した。送信機のピーク出力は20 Wに設定され、それは0.1 W / kgの比吸収率（SAR）に対応した。その結果、EMFばく露に反応したDPOAEレベルの有意な変化は検出されなかった、と報告している。
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To study potential effects of electromagnetic fields of GSM cellular phones on outer hair cells (cochlea) by means of distortion product otoacoustic emissions.
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.
|ばく露時間||intermittent, 3 min on/off=sham, for 24 min|
|Pulse width||0.5763 ms|
Transmission pause between consecutive pulses of the GSM-like signal was increased from 4.034 ms to 24.204 ms.
|Distance between exposed object and exposure source||5 cm|
|チャンバの詳細||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 information||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.