Figure 5.

Thermoacoustic signals after traveling through a monkey skull bone with a thickness of 6 mm: (a) Time shift is marked by two dotted perpendicular lines. The solid line is the thermoacoustic signal with the skull bone present, and the dotted line is the thermoacoustic signal with the skull bone absent. (b) Amplitude attenuation after phase shift has been compensated for. The solid line is the thermoacoustic signal with the skull bone present, and the dotted line is the thermoacoustic signal with the skull bone absent. (c) Comparison of the amplitude spectra of the thermoacoustic signals with and without the skull present.