The sound doesn't bounce and travel like it used to. These are black foam and I bought blue tacky to stick them up on the walls, because you need something porous. Tape didn't really work. I had to get these sound proofers because I make noise late at night but I also like to sing and music. These are really necessary, I don't know if you have to put these in alternating angles but I think it might help keep the sound from traveling too. There's no resonance and the sound is much clearer when you speak.
