1) I read in this forum that higher density fiber glass materials are better for sound absorption. But Alton Everest in his "Master Handbook of Acoustics" (4th edition pg 192) points that density does not matter as long as it is not very low. Could some one shed some light on this.
2) For corner bass traps made of 2 layers of 3" fiber glass panel, I read somewhere else* that using Roxul 40 (4lb/ft^3) is better than Roxul 60(6lb/ft^3) . Even though Roxul 60 has better absorption it is claimed that "as the bass trap thickness increases, less dense material is better", could some one explain why?