Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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William D. O'Brien, Jr. publications:

Michael L. Oelze publications:

Fundamental Acoustic Parameter Measurements

Some of the most useful physical parameters obtained from ultrasonic inquiry of a material are its acoustic attenuation, speed of sound, and quantitative backscatter coefficient.

Acoustic Attenuation: For this measurement a transmit transducer is aimed at a receive hydrophone placed roughly in its focal plane and adjusted to maximize the receive signal amplitude. Several measurements of the signal are recorded with only the degassed water between the transducer and hydrophone. This serves as a reference. The sample is then inserted in the path between transducer and hydrophone, and moved in lateral steps (usually a 5x5 square) so that signals taken through it are from independent regions of the material. The power spectrum (FFT) of each captured waveform signal is calculated and averaged over the number of independent positions in the sample; the amplitude of the final "sample" power spectrum is then compared to the averaged "reference" power spectrum of the water path alone. The difference is the "insertion loss", and dividing this value by the thickness of the sample gives attenuation in dB/cm.

Speed of Sound: The set up for this measurement is identical to that for the attenuation measurement above, and indeed both measurements are usually taken simultaneously. The propagation speed of sound through the material is determined from the time of flight in each case -- through the sample and through the water path alone -- using a cross-correlation technique.

Backscatter Coefficient: The backscatter coefficient of a material that scatters sound is defined as the differential scattering cross section per unit solid angle (at 180 degrees) per unit volume. In our measurements of backscatter coefficient, we compare the power spectrum of pulse-echo signals, gated to be at the desired depth in our sample, against the power spectrum of a perfect plane reflector (i.e. a polished steel plate, or the water/air interface) placed exactly at the position corresponding to half of the sampled depth in the specimen studied. These measurements are performed at separate times, and the positions are matched by recording the absolute time (referenced to the pulse trigger signal) of the signal maxima. In analyzing our data we use the method of Insana and Hall ("Parametric Ultrasound Imaging from Backscatter Coefficient Measurements: Image Formation and Interpretation", Ultrason. Image. vol. 12, pp. 245-267, 1990.) It is important to correct for the attenuation of the signal in the sample, so accurate values of acoustic attenuation must be measured before the backscatter coefficient is calculated. We also correct for the diffraction of the sound beam. Backscatter coefficients typically follow a power law in frequency, where, for example, a fourth power dependence indicates a Rayleigh scattering from objects much smaller than the sound wavelength.


References for Fundamental Acoustic Parameter Measurements

J. K. Brady, S. A. Goss, R. L. Johnston, W. D. O'Brien, Jr. and F. Dunn. Ultrasonic Propagation Properties of Mammalian Testes. Journal of the Acoustical Society of America, 60, 1407-1408, 1976.

W. D. O'Brien, Jr. The Role of Collagen in Determining Ultrasonic Propagation Properties in Tissue. Acoustical Holography, 7, 37-50, 1977.

W. D. O'Brien, Jr., J. K. Brady, C. N. Graves and F. Dunn. Preliminary Report on Morphological Changes to Mouse Testicular Tissue from In Vivo Ultrasonic Irradiation in Proceedings of the Bureau of Radiological Health Symposium on Biological Effects and Characterization of Ultrasound Sources, pp. 182-195, ed. by D.G. Hazzard, and M.L. Litz, U.S. Government Printing Office, Washington, D.C. 1977.

M. E. Stratmeyer, L. R. Simmons, G. L. Jessup, W. D. O'Brien, Jr. and F. Z. Pinkavitch. Growth and Development in Mice Exposed In Utero to Ultrasound in Proceedings of the Bureau of Radiological Health Symposium on Biological Effects and Characterization of Ultrasound Sources, pp. 140-145, ed. by D.G. Hazzard, and M.L. Litz, U.S. Government Printing Office, Washington, D.C., 1977.

W. D. O'Brien, Jr. The Relationship between Collagen and Ultrasonic Attenuation and Velocity in Tissue. In Proceedings of the Ultrasonics International 77, pp. 194-205, IPC Science and Technology Press Ltd., England, 1977.

F. Dunn and W. D. O'Brien, Jr. Ultrasonic Absorption and Dispersion. In Ultrasound: Its Application in Medicine and Biology, ed. by F. J. Fry, pp 393-439, Elsevier, The Netherlands, 1978.

S. A. Goss, R. L. Johnston, V. Maynard, L. Nider, L. A. Frizzell, W. D. O'Brien, Jr. and F. Dunn. Elements of Tissue Characterization, Part I, Ultrasonic Propagation Property Measurements. In Proceedings of the 2nd International Symposium on Ultrasonic Tissue Characterization, pp. 71-79 (NBS Special Publication 525) ed. by M. Linzer, U.S. Government Printing Office, Washington, D.C., 1979.

R. L. Johnston, S. A. Goss, V. Maynard, J. K. Brady, L. A. Frizzell, W. D. O'Brien, Jr. and F. Dunn. Elements of Tissue Characterization, Part II, Ultrasonic Propagation Properties. In Proceedings of the 2nd International Symposium on Ultrasonic Tissue Characterization, pp. 19-27 (NBS Special Publication 525) ed. by M. Linzer, U.S. Government Printing Office, Washington, D.C., 1979.

S. A. Goss and W. D. O'Brien, Jr. Direct Ultrasonic Velocity Measurements of Mammalian Collagen Threads. Journal of the Acoustical Society of America, 65, 507-511, 1979. ERRATUM: Journal of the Acoustical Society of America, 65, 1582, 1979.

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.

J. D. Pohlhammer and W. D. O'Brien, Jr. The Relationship Between Ultrasonic Attenuation and Speed in Tissues and Constituents: Water, Collagen, Protein and Fat. In Medical Physics of CT and Ultrasound: Tissue Imaging and Characterization, eds. G.D. Fullerton and J. A. Zagzebski, pp. 409-435, Medical Physics Monograph No. 6, American Association of Physicists in Medicine, American Institute of Physics, New York, NY, 1980.

J. Pohlhammer and W. D. O'Brien, Jr. Dependency of Ultrasonic Scatter Coefficient on Collagen Concentration in Mammalian Tissue. Journal of the Acoustical Society of America, 69, 283-285, 1981.

W. D. O'Brien, Jr., J. Olerud, J. M. Reid and K. K. Shung. Quantitative Acoustical Assessment of Wound Maturation with Acoustic Microscopy. Journal of the Acoustical Society of America, 69, 575-579, 1981.

J. D. Pohlhammer, C. A. Edwards and W. D. O'Brien, Jr. Phase Insensitive Ultrasonic Attenuation Coefficient Determination of Fresh Bovine Liver Over an Extended Frequency Range. Medical Physics, 8, 692-694, 1981.

M. A. McAvoy and W. D. O'Brien, Jr. Acoustic Velocity Using the Scanning Laser Acoustic Microscope (SLAM). Proceedings of the 1982 Ultrasonics Symposium, pp. 634-637, 1982.

P. M. Embree, S. G. Foster, G. Bright and W. D. O'Brien, Jr. Ultrasonic Velocity Spatial Distribution Analysis of Biological Materials with the Scanning Laser Acoustic Microscope. Acoustical Imaging, 13, 203-216, 1983.

W. D. O'Brien, Jr. and L. A. Segal. Frequency Dependent Ultrasonic Attenuation Coefficient Assessment in Fresh Tissue. Arch. Acoustics (Poland), 10, 11-14, 1983.

L. A. Segal and W. D. O'Brien, Jr. Frequency Dependent Ultrasonic Attenuation Coefficient in Fresh Tissue. Proceedings of the 1983 Ultrasonics Symposium, pp. 797-799, 1983.

K. M. U. Tervola, M. A. Grummer, J. W. Erdman, Jr. and W. D. O'Brien, Jr. Ultrasonic Attenuation and Velocity Properties in Rat Liver as a Function of Fat Concentration - A Study at 100 MHz using a Scanning Laser Acoustic Microscope. Journal of the Acoustical Society of America, 77, 307-313, 1985.

K. M. U. Tervola, S. G. Foster and W. D. O'Brien, Jr. Attenuation Coefficient Measurement Technique at 100 MHz with the Scanning Laser Acoustic Microscope. IEEE Transactions on Sonics and Ultrasonics, SU-32, 259-265, 1985.

P. M. Embree, K. M. U. Tervola, S. G. Foster and W. D. O'Brien, Jr. Spatial Distribution of the Speed of Sound in Biological Materials with the Scanning Laser Acoustic Microscope. IEEE Transactions Sonics and Ultrasonics, SU-32, 341-350, 1985.

C. A. Edwards and W. D. O'Brien, Jr. Speed of Sound in Mammalian Tendon Threads Using Reference Media. IEEE Transactions on Sonics and Ultrasonics, SU-32, 351-354, 1985.

K. M. U. Tervola and W. D. O'Brien, Jr. Spatial Frequency Domain Technique: An Approach to Analyze the Scanning Laser Acoustic Microscope. IEEE Transactions on Sonics and Ultrasonics, SU-32, 544-554, 1985.

K. M. U. Tervola, D. Steiger and W. D. O'Brien, Jr. Velocity and Attenuation Coefficient Measurement Techniques Using the Interferometric Mode of a 100 MHz Scanning Laser Acoustic Microscope. Proceedings Image Science '85, Acta nica Scandinavia, Applied Physics Series No. 150, Vol. 2, pp. 223-227, 1985.

M. J. Haney and W. D. O'Brien, Jr. Temperature Dependency of Ultrasonic Propagation Properties in Biological Materials. In Tissue Characterization with Ultrasound, Vol. I, J. F. Greenleaf (ed.), pp. 15-55, CRC Press, Inc., Boca Raton, FL, 1986.

E. L. Madsen, G. R. Franke, P. L. Carson, P. D. Edmonds, L. A. Frizzell, B. A. Herman, F. W. Kremkau, W. D. O'Brien, Jr., K. J. Parker and R. A. Robinson. Interlaboratory Comparison of Ultrasonic Attenuation and Speed Measurements. Journal of Ultrasound in Medicine, 5, 569-576, 1986.

J. E. Olerud, W. D. O'Brien, Jr., M. A. Riederer-Henderson, D. Steiger, F. K. Forster, C. Daly, D. J. Ketterer and G. F. Odland. Ultrasonic Assessment of Skin and Wounds with the Scanning Laser Acoustic Microscope. Journal of Investigative Dermatology, 88, 615-623, 1987.

W. D. O'Brien, Jr., J. W. Erdman, Jr. and T. B. Hebner. Ultrasonic Propagation Properties (@100 MHz) in Excessively Fatty Rat Liver. Journal of the Acoustical Society of America, 83, 1159-1167, 1988.

D. L. Steiger, W. D. O'Brien, Jr., J. E. Olerud, M. A. Riederer-Henderson and G. F. Odland. Measurement Uncertainty Assessment of the Scanning Laser Acoustic Microscope and Application to Canine Skin and Wound. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 35, 741-748, 1988.

M. A. Riederer-Henderson, J. E. Olerud, W. D. O'Brien, Jr., F. K. Forster, D. L. Steiger, D. J. Ketterer and G. F. Odland. Biochemical and Acoustical Parameters of Normal Canine Skin. IEEE Transactions on Biomedical Engineering, 35, 967-972, 1988.

C. M. W. Daft, G. A. D. Briggs and W. D. O'Brien, Jr. Frequency Dependence of Tissue Attenuation Measured by Acoustic Microscopy. Journal of the Acoustical Society of America, 85, 2194-2201, 1989.

J. E. Olerud, W. D. O'Brien, Jr., M. A. Riederer-Henderson, D. L. Steiger, J. Debel and G. F. Odland. Correlation of Tissue Constituents with the Acoustic Properties of Skin and Wound. Ultrasound in Medicine and Biology, 16, 55-64, 1990.

D. H. Agemura, W. D. O'Brien, Jr., J. E. Olerud, L. E. Chun and D. R. Eyre. Ultrasonic Propagation Properties of Articular Cartilage at 100 MHz. Journal of the Acoustical Society of America, 87, 1786-1791, 1990.

K. B. Sagar, D. H. Agemura, W. D. O'Brien, Jr., L. R. Pelc, T. L. Rhyne, L. S. Wann, R. A. Komorowski and D. C. Warltier. Quantitative Ultrasonic Assessment of Normal and Ischemic Myocardium with an Acoustic Microscope: Relationship to Integrated Backscatterer. Cardiovascular Research, 24, 447-455, 1990.

P. Tiernan, K. McCauley, T. Hebner, J. Erdman, Jr. and W. D. O'Brien, Jr. Ultrasonic Propagation Properties (at 100 MHz) in Liver of Rat Exposed to Ethanol or Carbon Tetrachloride. Proceedings of the Twelfth Annual International Conference of the IEEE Engineering in Medicine and Biology Society, pp. 299-300, 1990.

I. A. Hein, J. A. Novakofski and W. D. O'Brien, Jr. Ultrasound Data Acquisition System Design for Collecting High Quality RF Data from Beef Carcasses in the Slaughterhouse Environment. Proceedings of the 1992 IEEE Ultrasonics Symposium, pp. 1036-1044, 1992.

D. R. Gandhi and W. D. O'Brien, Jr. Nonlinear Acoustic Wave Propagation in Tissue. Proceedings of the 1993 IEEE Ultrasonics Symposium, pp 939-942, 1993.

G. Scherba, P.A. Hoagland and W.D. O'Brien, Jr. Acoustic Microscopy: A Study of Contrast in Fresh Tissue. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 41, 451-457, 1994.

E. J. Chen, J. Novakofski, K. Jenkins and W. D. O'Brien, Jr. Ultrasound Elasticity Measurements of Beef Muscle. Proceedings of the 1994 IEEE Ultrasonics Symposium, pp 1459-1462, 1994.

W. D. O'Brien, Jr., K. B. Sagar, D. C. Warltier and T. L. Rhyne. Acoustic Propagation Properties of Normal, Stunned and Infarcted Myocardium: Morphologic and Biochemical Determinants. Circulation, 91, 154-160, 1995.

P. D. O'Brien, W. D. O'Brien, Jr., T. L. Rhyne, D. C. Warltier and K. B. Sagar. Relationship of Ultrasonic Backscatter and Acoustic Propagation Properties to Myofibrillar Length and Myocardial Thickness, Circulation, 91, 171-175, 1995.

W. D. O'Brien and J. E. Olerud. Ultrasonic Assessment of Tissue Anisotropy. Proceedings of the 1995 IEEE Ultrasonics Symposium, pp 1145-1148, 1995.

E. J. Chen, J. Novakofski, W. K. Jenkins and W. D. O'Brien, Jr. Young's Modulus Measurements of Soft Tissues with Application to Elasticity Imaging. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 43, 191-194, 1996.

J. E. Assentoft, C. S. Joergensen, H. Gregersen, L. L. Christensen, J. C. Djurhuus and W. D. O'Brien, Jr. Characterizing Biological Tissue Using Scanning Laser Acoustic Microscopy. IEEE Engineering in Medicine and Biology Magazine, 15, 42-45, January/February, 1996.

T. Lwin and W. D. O'Brien, Jr. Tissue-Induced Ultrasonic Wavefront Distortion. Proceedings of the 1996 IEEE Ultrasonics Symposium, pp 1415-1418, 1996.

E. L. Madsen, F. Dong, G. R. Frank, B. S. Gara, K. A. Wear, T. Wilson, J. A. Zagzebski, H. L. Miller, K. K. Shung, S. H. Wang, E. J. Feleppa, T. Liu, W. D. O'Brien, Jr., K. A. Topp, N. T. Sanghvi, A. V. Zaitsen, T. J. Hall, J. B. Fowlkes, O. D. Kripfgans and J. G. Miller. Interlaboratory Comparison of Ultrasonic Backscatter, Attenuation and Speed Measurements. Journal of Ultrasound in Medicine, 18. 615-631, 1999.

J. E. Assentoft, H. Gregersen and W. D. O'Brien Jr. Determination of Biomechanical Properties in the Guinea-Pig Esophagus by Means of High Frequency Ultrasound and Impedance Planimetry. Digestive Diseases and Sciences (in press).

G. A. Teotico, R. J. Miller, L. A. Frizzell, J. F. Zachary and W. D. O'Brien, Jr. Attenuation Coefficient Estimates of Mouse and Rat Chest Wall. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control (in press).

J. E. Assentoft, H. Gresersen and W. D. O'Brien Jr. Propagation Speed of Sound Assessment in the Layers of the Guinea-pig Esophagus by Means of Acoustic Microscopy. Ultrasonics (in press).



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