have unfinished walls, adding insulation?

i have a garage that i'm in the process of converting to a studio. it is 23" wide 17" deep. ceiling slopes from 11.5" to 7.5" (across the 17" deep). at the moment all the walls are open. old 2x4 framing everywhere ...even the ceiling. most is 24" on center, some newer stuff is 16" on center. the short story is i've already spent 17k with residing, foundation, door, etc. . just going from shack to room. the initial idea was a room in a room design, but that will have to wait. i have to say i like the way it sounds. sure, there is bleed both in and out, but i have work arounds for the time being. something about all the old wood sounds good to me. there are 2 issues i do hear. 1, there is a ping. not sure if this is from stuff (there is a lot in the room) or the actual space. 2, i can hear some muddy modal action where the ceiling is lower. the best sounding place is about 5 feet out from the corners with high ceilings. i'm also beginning to realize is may be very hot/cold due to lack of insulation. quesion: i was thinking about insulating the ceiling and possibly the front face wall (hit by the sun) 23"x11.5". my thinking is the ceiling (shortest dimension) would be more problematic for modes. front face is the second shortest dimension. this way i'd have some reflective wood (long dimensions) and some dead walls (short) now it seems r-14 for 2x4s isn' going to cut it acoustically. i'd need compressed fiberglass, rockwool, etc. ideas? suggestions? thanks.

i was thinking about insulating the ceiling and possibly the front face wall (hit by the sun) 23"x11.5". my thinking is the ceiling (shortest dimension) would be more problematic for modes. front face is the second shortest dimension. this way i'd have some reflective wood (long dimensions) and some dead walls (short)

Well, modes are modes, and it doesn't really matter which way you look at them: they are all problematic, not just the vertical axial ones. Tangentials and obliques play their part too. With those dimensions, you have modal issues starting at 21 Hz and all the way up to 86 Hz, roughly. In fact, you have at least twenty nine modal issues, just between 20 Hz and 100 Hz. 9 are axials, 16 are tangential, and the final 4 are oblique. And that's just for the part of the ceiling that measures 7'6! With that steep slope on the ceiling and parallel walls with no treatment anywhere, you probably have all kinds of strange stuff going on, right across the low end of the spectrum! For the part for the ceiling that measures 11'6, you have 10 axials 18 tangentials and 8 obliques. And who-knows-what going on in between... :) When you say "insulate the ceiling", what do you actually mean by that? do you have exposed joists right now, inside your room, and you plan to put several inches of fiberglass or mineral wool in there, which will be remain visible in the room? If so, that will help a lot, especially if you make it thick. But if you have a drywall ceiling, and you plan to put insulation ABOVE that, then it really wont make much difference at all to the acoustics.

1, there is a ping. not sure if this is from stuff (there is a lot in the room) or the actual space. 2, i can hear some muddy modal action where the ceiling is lower. the best sounding place is about 5 feet out from the corners with high ceilings.

I'd say that you definitely also need bass trapping in there! If you have such noticeable modal issues, then just doing the ceiling wont be enough. I'd go for large bass traps in at least four corners, and more corners too, if you can. That would be my plan, if that were my room. - Stuart -

thanks for the reply. i never set my prefs to get an email so just getting back now. oh yes, there will be modes like crazy as you say. i've been doing some thinking and work on the space and have decided to go in a slightly diff direction. i'm still going to drywall between all the framing and ad r13. its 2x4 framing so r13 is all it will fit. it will be interesting to see how this sounds. it's not compressed or thick but it will be everywhere. i suspect very dead over 300hz and still problematic under 300hz. anyway this situation is only temp until the inner room is built. then 2 sheets of 5/8" drywall with green glue. if, IF, i do everything right. i should get an stc of say 60+. which would be heaven for me. after the isolation i'll tackle the room sound. i have 6 panels from gik acoustics and 4 bass traps. its a start. have to get my ears on it for a while.

if, IF, i do everything right. i should get an stc of say 60+. which would be heaven for me.

You won't get that until you finish the inner leaf. Your existing single leaf will get you maybe STC-30-something, if you are lucky, and beef it up really well.

anyway this situation is only temp until the inner room is built. then 2 sheets of 5/8" drywall with green glue.

... and on a separate decoupled stud frame!!! Or else you won't get STC-60 even then! If you have two separate frames, each with two layers of 5/8 drywall on one side, and a 10-inch air gap between the leaves, and isolation filling the entire cavity, and everything perfectly sealed, then theoretically you could get around STC-65 or better. Unless you put a door or window in, of course, in which case your overall isolation is defined by the door or window. Getting STC-65 in a door or window takes some doing!!!! - Stuart -

thanks for the info. i'm with you on this. i know my one leaf will do little. and yes the inner leaf will be independent. it will only share a huge 23"x17" concrete slab with a res freq of 3hz ...j/k don't know what the res would be. its very stiff but also very large and has a earthtech® damping system installed. should be low. early on i walled up the 3 windows. too much cost in keeping them. i have a heavy mdf-ish door which should match the outer leaf mass. the thing is def heavier then a like sized chunk of 5/8" drywall. but the seal is bad. have to go back to that. contractors did the work. what rod says is true about sound construction and standard construction. contractors just don't get acoustical considerations. i wish i had 2 friends all in San Francisco building studios...labor trade.