• Chandra, Rohit
• Johansson, Anders J.

Abstract

We have investigated the possibility of using the 2.45 GHz ISM band for communication between binaural hearing aids. The preliminary investigations were done by FDTD simulations on a modified SAM phantom head, where we have included a simple model of the ear canal. Two different types of hearing aid<br/> placements have been investigated: in the outer ear and in the ear canal. Antennas which have been miniaturized by applying disc loads and high permittivity materials were used for estimating the ear-to-ear link loss. The outer ear placement gives a total link loss of 48 dB and the placement in the ear canal gives a total link loss of 92 dB.<br/> Since the preliminary investigation indicated that the loss in the outer ear placement is low enough to support low power communication at 2.45 GHz, this configuration was chosen for further investigation on realistic heterogeneous human phantoms with proper electrical properties of all the tissues in the head. It was found that the antenna detunes differently for the different realistic phantoms and different ears within the same phantom.<br/> It was also found that the ear-to-ear link loss was 30 dB higher in a realistic heterogeneous phantom (named Duke of a 34 year old male) than in the SAM phantom. This was mainly due to the presence of an outer lossy layer (skin) and outer ears (pinna) in the Duke phantom. Other factors which may affect the ear-to-ear propagation channel like shoulders, metallic glass frame and size of the head have also been investigated.

Topics

• impedance spectroscopy
• simulation
• glass
• glass
• scanning auger microscopy