Abstract

Overview

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.

Findings

• 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 using 53 subjects in three different, controlled exposure scenarios: calling with the phone at the ear, calling in speaker-mode, and calling with a headset.
• Transmitted RF-EMF power was recorded during phone calls and specific absorption rate using numerical simulations.
• Sound pressure levels were recorded and speech intelligibility was assessed during each phone call.

Conclusion

The results indicate 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. However, this reduction in exposure might come at a cost of reduced speech intelligibility when background noise is present. The findings signal a significant trade-off smartphone users need to consider, concerning both exposure to potentially harmful EMFs and sound quality during calls.