Figure 2.

Illustration of group selection criteria and average spectra. The signals shown were acquired with the passive cavitation detector from Definity insonified at an incident PRPA of 2.0±0.2 MPa (5 cycles, 2.8 MHz). (a) PCD signals presenting a postexcitation signal after the principle response. (b) PCD signal showing only the principle response; no postexcitation signal. (c) Average power spectral density for signals with postexcitation response (N_t=18) and signals without postexcitation response (N=17).