Computational simulations of the penetration of 030 THz radiation into the human ear

There is an increasing interest in industrial and security applications and the establishment of wireless communication operating at frequencies of up to 0.30 THz. Soft tissue has a high coefficient of absorption at 0.30 THz and this limits effective penetration of the energy to a depth of 0.2 to 0.4 mm. The capacity of 0.30 THz radiation to access the deeper parts of the ear by diffusing through the ear canal and exposing the tympanic membrane (ear drum) to the radiation has not been studied. Simulations show that, with excitation parallel to the ear canal, the average power flux density within the central tympanic membrane region is 97% of the incident excitation. The structures of the outer ear are highly protective; less than 0.4% of the power flux density is directed at 45 degrees from the parallel reached the same region. Given the sensitivity of the tympanic membrane to mechanical change, in-vivo assessment of the penetration of 0.3 THz into the ear canal is warranted to assess the suitability of the present radiation safety limits and to inform 0.3 THz emitting device deign.