Foam does not work effectively for soundproofing as it has insubstantial mass to BLOCK sound whereas it is highly capable of ABSORBING sound. That is why 'acoustic foam' is for real and 'soundproof foam' is a myth.
What can I put on walls to absorb sound?
Cover walls with thick blankets, moving pads, tapestries, or quilts. Virtually any soft material will work, though thicker ones absorb more sound than thinner materials. If you don't mind adding an industrial look to the room, fasten sound-absorbing panels to the walls and, if necessary, the ceiling.5 feb 2021
Why is there padding on gym walls?
The primary purpose of wall padding is to provide a safe level of absorption for a person making impact with an established object. Often these objects are walls (hence ''wall padding''), but these pads also protect against impact with bleachers, stage fronts, I-Beams, goal posts, columns and fences.