(color online) Y: with mode conversions; N: without mode conversions; NAI: normalized acoustic intensity. Computational model numbers 1–8 represent the computational models in Figs. 3(a)–3(h), respectively. (a) Focusing deviation between real and designed focuses, (b) focusing gain of the acoustic intensity in the focal region and the maximal normalized acoustic intensity around the skull, (c) drop percentage of the focusing gain with mode conversions compared with focusing gain without mode conversions, and (d) ratio of the maximal normalized acoustic intensity around skull to focusing gain.