While browsing the technical data sheets of acoustic panels, you have certainly come across letter designations: A, B, C, D, or E. The association with school grades is quite accurate - class A is the "model student" that handles sound absorption the best. However, in interior design, "the best" does not always mean "the most cost-effective" for every area. How can you decipher these designations to choose a solution perfectly tailored to the room's function without overpaying? Here is a compendium of knowledge about absorption classes.