Generalized model of the microwave auditory effect

Abstract

A generalized theoretical model for evaluating the amplitudes of the sound waves generated in a spherical head model, which is irradiated by microwave pulses, is developed. The thermoelastic equation of motion is solved for a spherically symmetric heating pattern of arbitrary form. For previously treated heating patterns that are peaked at the sphere centre, the results reduce to those presented before. The generalized model is applied to the case in which the microwave absorption is concentrated near the sphere surface. It is found that, for equal average specific absorption rates, the sound intensity generated by a surface localized heating pattern is comparable to that generated by a heating pattern that is peaked at the centre. The dependence of the induced sound pressure on the shape of the microwave pulse is explored. Another theoretical extension, to the case of repeated pulses, is developed and applied to the interpretation of existing experimental data on the dependence of the human hearing effect threshold on the pulse repetition frequency.

Numerical simulation of pressure waves in the cochlea induced by a microwave pulse

“…In the case of the homogeneous spherical head model, for which analytical solutions have been derived [Lin, 1977a,b; Yitzhak et al, 2009] it was found that the pulse width dependence of the induced pressure amplitude at a given location in the head, and at an acoustic angular frequency ω m is of the form here, τ is the pulse width and the amplitude factor A is independent of the pulse width. We have found that this dependence on the pulse width holds to a good approximation even for the complicated biological models treated here.…”

“…This is not appropriate for the bottom layer of the head model, so in this case, an absorbing perfectly matched layer (PML; with a 10 cell thickness) was added [Chew and Liu, ]. We verified the accuracy of the elastic FDTD algorithm by applying it to the homogeneous sphere case, for which analytic solutions are available for comparison [Yitzhak et al, ].…”

“…In the case of the homogeneous spherical head model, for which analytical solutions have been derived [Lin, 1977a,b;Yitzhak et al, 2009] it was found that the pulse width dependence of the induced pressure amplitude at a given location in the head, and at an acoustic angular frequency v m is of the form…”

“…Shibata et al [] employed Lin's method, but with an improved specific heating pattern. A generalization of the analytic method, again using a homogeneous sphere head model, but with an arbitrary microwave absorption pattern of spherical symmetry, has been presented by Yitzhak et al []. The work of Watanabe et al [] is the first in which anatomically based head models were used to calculate the pressure waves generated by the thermoelastic expansion.…”

Sensing Magnetic Fields with Magnetosensitive Ion Channels

“…One of such manifestations is given by the microwave auditory effect or Allan Frey hearing effect [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ], an auditory perception of microwave pulses by humans and animals, which earlier has been considered mysterious. Now, the mystery of this effect is completely resolved within a thermoelastic theory [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] of acoustic wave production in closed resonators (e.g., human or animal head) filled with microwave absorbing tissues having a very large water content (think about heating of food in microwave oven, to realize a possible physical reason). Good reviews are available [ 13 , 14 , 15 ] and the theory and experiment agree convincingly well.…”