The foam devices serve to both absorb sound energy, and to scatter the remaining sound energy at a variety of angles, where much of it will collide with other reflected sound waves and cancel out.
I needed some acoustic foam for a small project at home and found this place. They seemed pretty affordable (and had lots of colors) compared to other places, though I'm far from an expert and I was only buying ~$40 of foam so I didn't exactly spent too much time comparison shopping: http://www.foambymail.com/acoustical-foam-products.html
Or, in an extreme example, the ones you see in anechoic chambers: https://www.google.com/search?q=anechoic+chamber&source=lnms...
The foam devices serve to both absorb sound energy, and to scatter the remaining sound energy at a variety of angles, where much of it will collide with other reflected sound waves and cancel out.
I needed some acoustic foam for a small project at home and found this place. They seemed pretty affordable (and had lots of colors) compared to other places, though I'm far from an expert and I was only buying ~$40 of foam so I didn't exactly spent too much time comparison shopping: http://www.foambymail.com/acoustical-foam-products.html