Abstract It is challenging to insulate sound transmission in low frequency-bands without blocking the air flow in a pipe. In this work. a small and light membrane-based cubic sound insulator is created to block acoustic waves in multiple low frequency-bands from 200 to 800 Hz in pipes. Due to distinct vibration modes of the membrane-type faces of the insulator and co-action of acousti... https://unitedssports.shop/product-category/ball-bag-team/