Fig. 1.

(a) PAM formation with aberration correction: RF signals are recorded from a source behind a skull. The data are beamformed in the spatial frequency domain using corrections from the known sound speed field $c(\mathit{r})$ with Eq. (5). (b) Experimental setup: Emissions from a known source are collected with a matrix array through a degassed human skull segment. (c) Sound speed registration: Using an acoustic image from the array and the micro-CT data, fiducial registration is used to obtain the transformation matrix. A semi-empirical model was used to convert the CT intensities to material properties.