Mobile phones: A trade-off between speech intelligibility and exposure to noise levels and to radio-frequency electromagnetic fields

Abstract

When making phone calls, cellphone and smartphone users are exposed to radio-frequency (RF) electromagnetic fields (EMFs) and sound pressure simultaneously. Speech intelligibility during mobile phone calls is related to the sound pressure level of speech relative to potential background sounds and also to the RF-EMF exposure, since the signal quality is correlated with the RF-EMF strength. Additionally, speech intelligibility, sound pressure level, and exposure to RF-EMFs are dependent on how the call is made (on speaker, held at the ear, or with headsets). The relationship between speech intelligibility, sound exposure, and exposure to RF-EMFs is determined in this study. To this aim, the transmitted RF-EMF power was recorded during phone calls made by 53 subjects in three different, controlled exposure scenarios: calling with the phone at the ear, calling in speaker-mode, and calling with a headset. This emitted power is directly proportional to the exposure to RF EMFs and is translated into specific absorption rate using numerical simulations. Simultaneously, sound pressure levels have been recorded and speech intelligibility has been assessed during each phone call. The results show that exposure to RF-EMFs, quantified as the specific absorption in the head, will be reduced when speaker-mode or a headset is used, in comparison to calling next to the ear. Additionally, personal exposure to sound pressure is also found to be highest in the condition where the phone is held next to the ear. On the other hand, speech perception is found to be the best when calling with a phone next to the ear in comparison to the other studied conditions, when background noise is present. Thielens et al., 2013). These values were then renormalized to a TX power of 1 W. We chose not to model the wire of the headset in the 'Headset' configuration. Data Processing and AnalysisThe registered TX powers during each call were pooled for all participants, calls and frequencies, but split for the three exposure conditions, the two locations, and the communication technology. We chose to split the data for the two locations, since the coverage and link with the network might have been different. We chose to split the data for the different telecommunication technologies since they have distinctly different ranges of operation in terms of emitted power. We did not split the GSM results in 900 MHz and 1800 MHz. A Wilcoxon Rank Sum (WRS) test and a two-sided Kolmogorov-Smirnov (K-S) test were then used to determine whether the TX power in different exposure situations on the same test site were significantly different (significance level of 5%). In a second step, all TX powers that were recorded for GSM were multiplied by the SAR brain values at the appropriate frequency and exposure condition. Those instances where WCDMA was used to establish communication were not treated for SAR, because we did not have full information on the used frequency during those events. However, they were considered for the analysis of emitted powers. The obtained...

Pilot study of a new methodology to study the development of the blue bottle fly (Calliphora vomitoria) under exposure to radio-frequency electromagnetic fields at 5.4 GHz

“…The authors measured 0.9-3.8 V/m E-field strengths emitted by the mobile phone on a single time instance. However, it is known from literature that RF-powers emitted by a mobile phone can show variations of more than a factor 1000 during a call and that a mobile phone can dynamically switch emitting frequency (Thielens et al 2019;Joshi et al 2015), so the actual exposure level and frequency of the exposed group was unknown. The exposure of the sham group was never measured, while this group was exposed to environmental fields.…”

Using TRIZ Theory to Create Prototypes to Reduce the Potential Impact of a Phone’s Magnetic Field on the Human Body

“…Apart from changing the habit of using mobile phones [5], not many studies provide practical solutions or physical devices to prevent the EMF emitted by phones. There are some products in the market that claim to prevent the EMF emitted by phones; however, most of them use a shielding method, which does not reduce the harm to human health [6]. Although the ICNIRP international guideline for phone radiation safety has been established, it does not reflect the actual EMF amount that can safely be absorbed by the human body [5].…”

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“…Different study methods, types of measuring equipment and means to carry them have been evaluated [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. For instance, the personal exposimeter has been carried in a bag next to the researcher's body [10,11,20], in a plastic basket on a bicycle [21,22], in a cardboard tube held above the researcher's head [23,24], on the top of a car or different ExpoM-RF devices have been mounted inside a box in a small car [25], or on a drone [26].…”