Effects of Bluetooth device electromagnetic field on hearing: pilot study R BALACHANDRAN, N PREPAGARAN, O RAHMAT, A B ZULKIFLEE, K S HUFAIDA Department of Otorhinolaryngology, University of Malaya, Kuala Lumpur, Malaysia Abstract Background: The Bluetooth wireless headset has been promoted as a ‘hands-free’ device with a low emission of electromagnetic radiation. Objective: To evaluate potential changes in hearing function as a consequence of using Bluetooth devices, by assessing changes in pure tone audiography and distortion production otoacoustic emissions. Design: Prospective study. Materials and methods: Thirty adult volunteers were exposed to a Bluetooth headset device (1) on ‘standby’ setting for 6 hours and (2) at full power for 10 minutes. Post-exposure hearing was evaluated using pure tone audiography and distortion production otoacoustic emission testing. Results: There were no statistically significant changes in hearing, as measured above, following either exposure type. Conclusion: Exposure to the electromagnetic field emitted by a Bluetooth headset, as described above, did not decrease hearing thresholds or alter distortion product otoacoustic emissions. Key words: Bluetooth Headset; Electromagnetic Fields; Cochlea; Hearing Loss Introduction The introduction of Bluetooth technology has rep- resented a significant advance in the wireless technol- ogy used in mobile phones. However, the widespread use of Bluetooth technology has raised questions regarding possible health effects. Consequently, the biological effects of this technology have become an issue of public and scientific concern. Bluetooth devices are used in close proximity to the auditory system; thus, this may be the most affected system. It has not been conclusively proven that short term exposure to the electromagnetic field emitted by mobile phones causes auditory damage. 1 – 5 However, long term exposure to mobile phones has been linked to hearing loss. 6,7 The hearing effects of Bluetooth devices have not yet been studied. In general, Bluetooth devices are used for longer time periods, in comparison to mobile phones, and are usually kept on ‘standby’ when not in use. What is Bluetooth? Bluetooth technology is a global standard for short range, radio frequency transmission which was devel- oped to enable wireless connectivity. Bluetooth devices operate in the unlicensed industrial, scientific and medical bandwidth (2.400 to 2.485 GHz). They are categorised into three classes, the commonest of which are class two devices; these produce up to 2.5 mV and have a range of up to 10 m, similar to most mobile phones. 8 Both mobile phones and Bluetooth devices emit non-ionising electromagnetic radiation. The Bluetooth wireless headset device has been claimed to reduce the effects of electromagnetic radi- ation on the auditory system. The average specific absorption rate of these devices is thought to be far below that of mobile phones. The present study assessed the effects of a specified period of Bluetooth device usage on human hearing, in both standby and active modes. Materials and methods This study aimed firstly to study potential changes in hearing function as a consequence of Bluetooth device usage, as determined by changes in distortion product otoacoustic emissions (DPOAEs) and pure tone audiometry (PTA) at suprathreshold levels. The study also aimed to detect any difference in hearing threshold change after using Bluetooth devices in standby versus active modes. Presented at the 13th ASEAN ORL-HNS Congress, 12 November 2009, Siem-Reap, Cambodia Accepted for publication 14 June 2011 First published online 6 February 2012 The Journal of Laryngology & Otology (2012), 126, 345–348. MAIN ARTICLE © JLO (1984) Limited, 2012 doi:10.1017/S0022215112000047