Investigation of potential effects of cellular phones on human auditory function by means of distortion product otoacoustic emissions

Abstract

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.

Neurophysiological effects of mobile phone electromagnetic fields on humans: A comprehensive review

“…Otoacoustic emission studies selected for our review did not show any effects after exposure to GSM signals [Janssen et al, 2005;Parazzini et al, 2005;Uloziene et al, 2005]. In fact, besides the great amount of research on the peripheral and central auditory function, there is a lack of fully blind experiments and replications, as with ERP literature, where the authors focus on more central indexes of cerebral information processing.…”

“…Indeed, only a few studies met our selection criteria and were thus considered for the review. Three of these are evoked otoacoustic emission studies which highlighted a lack of effects [Janssen et al, 2005;Parazzini et al, 2005;Uloziene et al, 2005], whereas other researchers pointed out a significant variation of the acoustic temporal correlation coefficients following EMF exposure, found both in healthy and epileptic patients [Maby et al, 2005]. Krause et al [2006] 15 children (6 M, 9 F) Finally, the only study using magnetoencephalography (MEG) evaluated the effects of GSM 1800 (217Hz and .125/1 W of power) on memory during encoding of verbal material [Hinrichs and Heinze, 2004].…”

Impact of occupational noise on pure-tone threshold and distortion product otoacoustic emissions after one workday

“…Due to these SNRs, it could be expected that the DPOAE level L dp exhibited a test-retest-variability of less than 1 dB (see Fig. 2 in Janssen et al, 2005). Differences in calibration transfer functions between measurements before and after work (see Section 2.4) amounted to 2.0 dB [3.1 dB] (noise exposure group) and 1.4 dB [1.7 dB] (control group), respectively.…”

“…Especially distortion product otoacoustic emissions (DPOAEs), generated by OHCs when stimulated with two tones (Kemp, 1986;Brownell, 1990), are a highly sensitive means for assessing minute changes in OHC functionality (Hall and Lutman, 1999;Attias et al, 2001;Marshall et al, 2001;Janssen et al, 2005).…”

Auditory Brainstem Response Changes during Exposure to GSM-900 Radiation: An Experimental Study

“…On the other hand, no harmful effects of mobile phone usage have been reported regarding hearing, tinnitus and balance in a student population detected by a self-report method [Davidson and Lutman, 2007]. After Grisanti's first reported changes in distortion product otoacoustic emissions attributed to mobile phone use, many researchers failed to find any significant effect of mobiles on distortion product otoacoustic emissions [Grisanti et al, 1998;Aran et al, 2004;Monnery et al, 2004;Galloni et al, 2005;Janssen et al, 2005;Parazzini et al, 2005;Mora et al, 2006]. Recently, in a case-control study, no significant transient evoked otoacoustic emission changes from baseline to postexposure recording for any of the subjects, nor any significant differences in the transient evoked otoacoustic emission change from baseline to postexposure between cases and controls were reported [Bamiou et al, 2008].…”