Fast compression wave group velocity, ○ ○ ○ experiment, 20 cm H2O, ––– Biot theory, 20 cm H2O, –.– effective medium model, 20 cm H2O, ◻ ◻ ◻ experiment, 10 cm H2O, – – Biot theory, 10 cm H2O, - - - effective medium model, 10 cm H2O. Bars on the experimental data denote a 95% confidence interval, as described in Sec. 4.