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IEEE Transactions on Microwave Theory and Techniques
Volume 48 Number 11, November 2000

Table of Contents for this issue

Complete paper in PDF format

FDTD Analysis of Microwave Hearing Effect

Yoshiaki Watanabe, Toshiyuki Tanaka, Member, IEEE Masao Taki and So-ichi Watanabe Member, IEEE

Page 2126.

Abstract:

This paper presents a numerical analysis of the thermoelastic waves excited by the absorbed energy of pulsed microwaves in a human head. First, we calculate the distribution of the specific absorption rate using a conventional finite-difference time-domain (FDTD) algorithm for the Maxwell's equation. We then calculate the elastic waves excited by the absorbed microwave energy. The FDTD method is again applied to solve the elastic-wave equations. The validity of the analysis for elastic waves is confirmed through comparison of the FDTD results with the analytical solutions in a sphere model. Two anatomically based human head models are employed for numerical calculations. The waveforms of the calculated pressure waves are different from the previously reported ones. It is especially shown that the surface heating is important in exciting the fundamental mode of the pressure waves in the head. The pulsewidth dependency of the loudness of microwave hearing is clearly explained by the simulation with realistic head models. The peak pressure of elastic waves in the realistic head models is of the same order as the previously reported values obtained with a homogeneous sphere model. The strength of elastic wave is discussed in consideration of the safety of this phenomenon.

References

  1. A. H. Frey and R. Messenger, Jr., "Human perception of illumination with pulsed ultra-high frequency electromagnetic energy", Science, vol. 181, pp.  356-358, 1973.
  2. K. R. Foster and E. D. Finch, "Microwave hearing: Evidence for thermoacoustic auditory stimulation by pulsed microwaves", Science, vol. 185, pp.  256-258, 1974.
  3. C. K. Chou, R. Galambos, A. W. Guy and R. H. Lovely, "Cochlea microphonics generated by microwave pulses", J. Microwave Power, vol. 10, pp.  361-367, 1975.
  4. J. C. Lin, "Microwave auditory effect-A comparison of some possible transduction mechanisms", J. Microwave Power, vol. 11, pp.  77-81, 1976 .
  5. J. C. Lin, "On microwave-induced hearing sensation", IEEE Trans. Microwave Theory Tech., vol. MTT-25, pp.  605-613, July  1977.
  6. J. C. Lin, "Further studies on the microwave auditory effect", IEEE Trans. Microwave Theory Tech., vol. MTT-25, pp.  939-943, July  1977.
  7. V. V. Tyazhelov, R. E. Tigranian, E. O. Khizhniak and I. G. Akoev, "Some peculiarities of auditory sensations evoked by pulsed microwave fields", Radio Sci., vol. 14, no.  6S, pp.  259-263, 1977.
  8. J. C. Lin, "Microwave auditory phenomenon", Proc. IEEE , vol. 68, pp.  67-68, Jan.  1980.
  9. R. G. Olsen and J. C. Lin, "Microwave pulse-induced resonances in spherical head models", IEEE Trans. Microwave Theory Tech., vol. MTT-29, pp.  1114-1117, Oct.  1981.
  10. C. K. Chou and A. W. Guy, "Auditory perception of radio-frequency electromagnetic fields", J. Acoust. Soc. Amer., vol. 71, pp.  1321-1334, 1982.
  11. R. G. Olsen and J. C. Lin, "Microwave-induced pressure waves in mammalian brains", IEEE Trans. Biomed. Eng., vol. BME-30, pp.  289-294, May  1983 .
  12. T. Shibata, O. Fujiwara, K. Kato and T. Azakami, "Calculation of thermal stress inside human head by pulsed microwave irradiation", IEICE Trans. Commun., vol. J69-B, no. 10, pp.  1144-1146,  1986.
  13. J. C. Lin, "Auditory perception of pulsed microwave radiation,"in Biological Effects and Medical Applications of Electromagnetic Energy , O. P. Gandhi, Ed. Englewood Cliffs, NJ: Prentice-Hall, 1990, pp.  277-318. 
  14. ICNIRP "Guidelines for limiting exposure to time-varying elestric, magnetic and electromagnetic fields (up to 300 GHz)", Health Phys., vol. 74, no. 4, pp.  494 -522, 1998.
  15. "IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields 3 kHz to 300 GHz", ANSI/IEEE Standard C95.1-1992, 1992.
  16. S. Watanabe, M. Taki, T. Nojima and O. Fujiwara, "Characteristics of the SAR distributions in a head exposed to electromagnetic fields radiated by a hand-held portable radio", IEEE Trans. Microwave Theory Tech., vol. 44, pp.  1874-1883, Oct.  1996.
  17. O. P. Gandhi, G. Lazzi and C. M. Furse, "Electromagnetic absorption in the human head and neck for mobile telephones at 835 and 1900 MHz", IEEE Trans. Microwave Theory Tech., vol. 44, pp.  1884-1897, Oct.  1996.
  18. O. Fujiwara and A. Kato, "Computation of SAR inside eyeball for 1.5-GHz microwave exposure using finite-difference time-domain technique", IEICE Trans. Commun., vol. E77-B, pp.  732-737, 1994.
  19. C. Gabriel, "Compilation of the dielectric properties of body tissues at RF and microwave frequencies", Armstrong Laboratory, Brooks Air Force Base, Brooks AFB, TX, Tech. Rep. AL/OE-TR-1996-0037, 1998.
  20. L. Kunz, The Finite Difference Time Domain Method for Electromagnetics, Boca Raton, FL: CRC Press, 1993.
  21. J.-P. Berenger, "A perfectly matched layer for the absorption of electromagnetic waves", J. Comput. Phys., vol. 114, no. 1, pp.  185-200, 1994.
  22. W. C. Chew and Q. H. Liu, "Perfectly matched layers for elastrodynamics: A new absorbing boundary condition", J. Comput. Acoust., vol. 4, no.  4, pp.  341-359, 1996.
  23. D. N. Fenner, P. B. Robinson and P. M.-Y. Cheung, "Three-dimensional finite element analysis of thermal shock in a premolar with a composite resin MOD restoration", Med. Eng. Phys., vol. 20, pp.  269-275, 1998.
  24. V. K. Goel, H. Park and W. Kong, "Investigation of vibration characteristics of the ligamentous lumber spine using the finite element approach", ASME J. Biomech. Eng., vol. 116, pp.  337-383, 1994.
  25. R. G. Gordon, R. B. Roemer and S. M. Horvath, "A mathematical model of the human temperature regulatory system-Transient cold exposure response", IEEE Trans. Biomed. Eng., vol. BME-23, pp.  434-444, Nov.  1976.
  26. J. A. Stratton, Electromagnetics Theory, New York: McGraw-Hill, 1941.
  27. J. F. Corso, "Bone-conduction thresholds for sonic and ultrasonic frequencies", J. Acoust. Soc. Amer., vol. 35, no. 11, pp.  1738-1743, Nov.  1963.
  28. R. L. Powis and W. J. Powis, "Bioeffects of ultrasound on tissue,"in A Thinker's Guide to Ultrasonic Imaging, Baltimore, MD: Urban & Schwarzenberg, 1984, pp.  239-253.