Vicoustic Acoustic Treatment
Vicoustic USA is a company new to me in the field of acoustic treatment. They offer a wide range of products, including some unique absorbers and diffusers, for that application. Many of them are less expensive, in my experience, than many of the similar devices currently available. They begin as low as $75 each for an approximately 2-foot square panel (but only available in a package of 10), though the prices can escalate rapidly when you get to premium products such as all wood diffusers.