Sound waves are really long. 20kHz is about the limit of human hearing, so the shortest wave we can hear is about 17cm; the longest wave we can hear is about 17

Sound waves are really long. 20kHz is about the limit of human hearing, so the shortest wave we can hear is about 17cm; the longest wave we can hear is about 17 meters. A suitably designed mesh will be effectively transparent across that frequency range.