Ultrasonic absorption and attenuation in mammalian tissues.

-The ultrasonic absorption was determined, by the transient thermoelectric method, for brain, heart, kidney, liver, tendon, and testis from cat, mouse, pig and beef. Comparison of these absorption {a) values with published values of attenuation (A) shows: (1) that the a and A coefficients have nearly the same frequency dependencies in the range 0.5-7 MHz, (2) that the magnitudes of a and A differ appreciably and that difference depends upon the method of measurement and tissue type, and (3) that there appears to be little species difference, at least as revealed by measurement of liver and tendon.