Fig. 4.

(a) Calculated temporal response for ${\mu }_a=6.4$ mm⁻¹ at a depth of 300 mm, exhibiting 49.3 Pa peak-to-peak pressure, inset shows the response of a 1 mm thick absorber as function of ${\mu }_a$. (b) Spectrum for ${\mu }_a=6.4$ mm⁻¹, with an inset showing spectra as function of ${\mu }_a$. The red line follows the maximum amplitude, the black lines encompass the −6 dB cut-offs of the spectra.