1. An ultrasonic living body tissue characterization method, comprising the steps of: (a) transmitting an ultrasonic pulse into the body tissue, receiving an echo reflected from within the body tissue and producing an echo signal from the echo; (b) converting a portion of the echo signal corresponding to a depth z into a power spectrum; (c) deriving a tissue power transfer function, R(f), of the portion utilizing a reference power spectrum obtained at the depth z in a reference medium where f indicates frequency within the spectrum; (d) finding a maximum, Rm, of the tissue power transfer function R(f) and a frequency, fm, at which the maximum Rm occurs; (e) normalizing the tissue power transfer function R(f) with the maximum Rm; (f) producing a normalized frequency y in accordance with y=f/fm and substituting the normalized frequency, y, for the frequency f; and (g) extracting a reflection power exponent, n, from the shape of the normalized tissue power transfer function R(f)/Rm as a function of the normalized frequency y and the reflection power exponent n.