Roxul ,Safe N Sound Insulation Being Used For quieting HP Air Handler

[Mel Fulks]

When there is no need for thermal insulation, is there any value in compressing Roxul for more quieting?

[Ralph Okonieski]

I do not know about compressing it. I used in in the ceiling of my basement shop where it works very well. Reduced the noise in the family room above it by a significant amount.

[Mel Fulks]

Ralph, thanks. I've used it before just for thermal and noticed it did good job of quieting,too. I know that product density can be helpful in sound proofing. But I have no idea if compression is helpful with Roxul. Could be a long night of playing the stereo at top volumn, nailing up different thicknesses of Roxul over the windows ,then listening outdoors while recording data....how else can science advance!?

[Allan Speers]

Compressing mineral wool, or any other semi-rigid insulation, will simply change the frequency that get most absorbed.

the typical 2-4 lbs per sq inch absorbs quite evenly from around 125 HZ to 8K or more. 5 lbs absorbs more energy in the 125 HZ range, less in the higher frequencies. So, if your machinery mostly rumbles at around 125 - 250 HZ, compressing would be a good idea. - Or leave it alone and add some sound board behind it.

note: You can squash it all day, but it still won't absorb much below 125HZ. For that, you need bass traps.

If you have any specific questions, feel free to ask & I'll help as I can. (time permitting.) I used to design recording studios for a living, and know this stuff inside-out.

[Mel Fulks]

Allan, most kind and helpful and stated so I understand it. Thank you.