High-resolution numerical model of the middle and inner ear for a detailed analysis of radio frequency absorption.

In order to enable a detailed analysis of radio frequency (RF) absorption in the human middle and inner ear organs, a numerical model of these organs was developed at a spatial resolution of 0.1 mm, based on a real human tissue sample. The dielectric properties of the liquids (perilymph and endolymph) inside the bony labyrinth were measured on samples of ten freshly deceased humans. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-3700 MHz were carried out. For typical output power values of real handheld mobile communication devices the obtained results showed only very small amounts of absorbed RF power in the middle and inner ear organs. Highest absorption in the middle and inner ear was found for the 400 MHz irradiation. In this case, the RF power absorbed inside the labyrinth and the vestibulocochlear nerve was as low as 166 microW and 12 microW, respectively, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power were found to be more than one order of magnitude lower than the values given above. These results indicate that temperature-related biologically relevant effects on the middle and inner ear, induced by the RF emissions of typical handheld mobile communication devices, are unlikely.