Janssen Thomas, Boege Paul, von Mikusch-Buchberg Jutta, Raczek Johannes
ENT-Department, Laboratory for Experimental Audiology, Technical University Munich, Germany.
J Acoust Soc Am. 2005 Mar;117(3 Pt 1):1241-7. doi: 10.1121/1.1854331.
Outer hair cells (OHC) are thought to act like piezoelectric transducers that amplify low sounds and hence enable the ear's exquisite sensitivity. Distortion product otoacoustic emissions (DPOAE) reflect OHC function. The present study investigated potential effects of electromagnetic fields (EMF) of GSM (Global System for Mobile Communication) cellular phones on OHCs by means of DPOAEs. DPOAE measurements were performed during exposure, i.e., between consecutive GSM signal pulses, and during sham exposure (no EMF) in 28 normally hearing subjects at tone frequencies around 4 kHz. For a reliable DPOAE measurement, a 900-MHz GSM-like signal was used where transmission pause was increased from 4.034 ms (GSM standard) to 24.204 ms. Peak transmitter power was set to 20 W, corresponding to a specific absorption rate (SAR) of 0.1 W/kg. No significant change in the DPOAE level in response to the EMF exposure was found. However, when undesired side effects on DPOAEs were compensated, in some subjects an extremely small EMF-exposure-correlated change in the DPOAE level (< 1 dB) was observed. In view of the very large dynamic range of hearing in humans (120 dB), it is suggested that this observation is physiologically irrelevant.
外毛细胞（OHC）被认为起着压电换能器的作用，可放大低声强，从而使耳朵具有极高的灵敏度。畸变产物耳声发射（DPOAE）反映了外毛细胞的功能。本研究通过DPOAE研究了全球移动通信系统（GSM）手机的电磁场（EMF）对外毛细胞的潜在影响。在28名听力正常的受试者中，于4kHz左右的纯音频率下，在暴露期间（即连续GSM信号脉冲之间）以及假暴露（无电磁场）期间进行DPOAE测量。为了进行可靠的DPOAE测量，使用了一种类似900MHz GSM的信号，其传输暂停时间从4.034毫秒（GSM标准）增加到24.204毫秒。发射机峰值功率设置为20W，对应比吸收率（SAR）为0.1W/kg。未发现电磁场暴露后DPOAE水平有显著变化。然而，当对DPOAE的不良副作用进行补偿后，在一些受试者中观察到DPOAE水平有与电磁场暴露相关的极小变化（<1dB）。鉴于人类听力的动态范围非常大（120dB），提示该观察结果在生理上不相关。
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