The human ear... in most adult cases can hear cleanly to 18hz.... and then b/c most subwoofers don't play it... the human ear loses sound....
Well the human hearing can extend downwards to 16hz and as far as the high cutoff.... I don't know. The typical teenager that abuses rock music and rap can usually hear no lower than 19 or 18hz.... small children's hearing is a bit more sensitive....