Fig. 5. Box and whisker plots of (A) sound speed corrected to 37°C, (B) mass density and (C) CT scan Hounsfield units for various tissue types in the forehead and mandible. The lines of the boxes represent the lower-quartile, median and upper-quartile values. The whiskers extending from each end of the box show the extent of the remaining data. Outliers are represented by + signs beyond the whiskers. The dark blue horizontal lines represent the sound speed (1507 m s^–1), density (1026 kg m^–3) and HU (0), respectively, of seawater at 15°C and 101 kPa.