Ultrasound Absorption Coefficient Facility

The transient thermoelectric technique for measurement of the absorption coefficient in biological materials was developed by William Fry and colleagues in the Bioacoustics Research Laboratory in the early 1950s. This technique continues to be the only technique for directly measuring the absorption coefficient, as opposed to the attenuation coefficient which includes effects of scattering in addition to absorption, in inhomogeneous tissue samples. Over the years since its development many measurements have been made in this laboratory (see references below) and others using this technique or modifications of it.

Very briefly the measurement technique uses very small diameter thermocouples that are inserted into the tissue to measure the rate of temperature rise as the tissue is sonicated with an ultrasound beam of known intensity. Using the density and heat capacity of the tissue and the depth of the thermocouple one can easily calculate the absorption coefficient in the sample.

References

W. J. Fry and R. B. Fry. Determination of Absolute Sound Levels and Acoustic Absorption Coefficients by Thermocouple Probes - Theory. Journal of the Acoustical Society of America, 26, 294-310, 1954.

W. J. Fry and R. B. Fry. Determination of Absolute Sound Levels and Acoustic Absorption Coefficients by Thermocouple Probes - Experiment. Journal of the Acoustical Society of America, 26, 311-317, 1954.

D. W. Duback, L. A. Frizzell and W. D. O'Brien, Jr. An Automated System for Measurement of Absorption Coefficients Using the Transient Thermoelectric Technique. Proceedings of the 1979 Ultrasonic Symposium, pp. 388-391, 1979.

K. I. Bailey, W. D. O'Brien, Jr. and F. Dunn. Ultrasonically Induced Temperature Elevation in Mouse Ovary. Ultrasound in Medicine and Biology, 10, L492-L499, 1984.

S.A. Goss, J. W. Cobb, and L. A. Frizzell. Effect of Beam Width and Thermocouple Size on the Measurement of Ultra-sonic Absorption Using the Thermoelectric Technique. 1977 Ultrasonics Symposium Proceedings, IEEE Cat. No. 77CH 1264-1SU, pp. 206-211, 1977.

S.A. Goss, L. A. Frizzell, and F. Dunn. Frequency Dependence of Ultrasonic Absorption in Mammalian Testis. Journal of the Acoustical Society of America, 63, 1226-1229, 1978.

S.A. Goss, L. A. Frizzell, and F. Dunn. Ultrasonic Absorption and Attenuation in Mammalian Tissues. Ultrasound in Medicine and Biology, 5, 181-186, 1979.

J.L. Drewniak, L. A. Frizzell, and F. Dunn. Errors Result-ing from Finite Beam width and Sample Dimensions in the Determination of the Ultrasonic Absorption Coeffi-cient. Journal of the Acoustical Society of America, 88, 967-977, 1990.