Translate This PageSoundman2020 wrote:It's still a triple-leaf, just not as effective as if it were sealed.
Ah okay, fair enough.
Soundman2020 wrote:A while ago there was a post on another forum (don't recall where) about someone who was working on his studio while playing music inside (helps with the boredom!). At one point, he was working outside the studio with the door closed, and as he leaned a sheet of drywall up against the outer wall, the music from inside suddenly became audible, and he could feel slight vibrations with his fingers, from the sheet of drywall. As long as he held it up close to the outer-leaf, there was an audible effect, even though the "cavity" was completely unsealed. It wasn't huge, but it was noticeable. Sympathetic resonance is a real thing.
My thinking was that if that outer leaf wasn't there at all (in your example) and that sheet was held in the same place picking up the vibrations, then the drywall would vibrate even more because it would receive more energy (previously blocked by outer leaf). So I figured the extra wall / outer leaf would attenuate things so much that the wall next to it would barely be effected. However, I am not experienced with room design so will take your word for it
And yes it'd take up an extra few inches which would be a pain!Soundman2020 wrote:Your inner-leaf ceiling joists rest only on the inner-leaf walls. No connection at all to the outer leaf. The "inner room" is a complete, stand-alone structure. Not even a single nail can bridge to the outer leaf. So there won't be any flanking through that.
Soundman2020 wrote:This is also why I recommend using OSB as the first layer ob your wall studs: It add a lot of structural integrity to the walls, especially in sheer. The studs themselves do a great job of supporting the weight of whatever is on top of them, but simple stud framing isn't strong in sheer, which is the "side to side" direction along the plane of the wall itself. Imagine a free-standing frame, out it the open with nothing supporting it. Just a sole plate, a few vertical studs, and a pair of top plates. If you go stand at one end of that wall, and push at the top along the wall (in the same direction that the top plates run), you'll see that it isn't strong at all. Without too much effort, you can make it wobble, and with enough force, you can collapse it over sideways. But if you nail a sheet of OSB onto those studs, you can't do that any more. It makes the entire wall a lot more rigid, and very strong in sheer. So doing that to all of the walls gives you a massive increase in structural integrity, which you need to support the ceiling properly.
Okay cool I will do that
Definately on the inner room. The new outer wall will not be load bearing, so that could be different if there's any benefit to it being different..Will green glue still be okay if I do [OSB GG Plasterboard] (or maybe [OSB GG FibreCement]) ?
Soundman2020 wrote:Was that on your cell phone with an app, or using a proper sound level meter? Cell phone mics and electronics are not very good for low frequencies, because they are mainly meant to capture your voice as you speak on the phone, and your voice has practically no useful energy below maybe 150 Hz or so. So the mic just isn't sensitive down low. Also, the mic on your cell phone is specifically designed to NOT be omnidrectional, in order to reject ambient noise as mush as possible. Acoustic measurement mics (such as those on proper sound level meters) MUST be omnidrectional, so they can capture the full sound field from all sides. So a cell-phone app can give you a rough idea of levels, but isn't accurate, and especially not down in the low end.
I was using my phone at the time yes. I used the NIOSH app, which after comparing with my calibrated UMIK-1 seems pretty accurate, even down low. The IPhone mic is pretty good, and the NIOSH app is calibrated for that particular phone (so probably boosts the bass). But I hear you, I will use the calibrated mic for the proper tests. 115dB does seem to be mentioned as a general rule of thumb for drums peaking so it probably isn't far out, though again there were other instruments playing. Really I need to do the test in-situ, and measure next door too while playing (still organising that).
Soundman2020 wrote:Second question: Did you have the meter (or app) set to "C" weighting?
Pretty sure I had it on C.
Soundman2020 wrote:So when testing isolation, you should always use "C", not "A". (The good thing is that most municipal noise regulations specify levels in "A" weighting, so you have the big benefit there, of the cops come knocking on your door!)
Haha, will remember that. Hopefully if I do this right the cops won't come knocking
Also the neighbours would call/text/nip round first before even considering that.Soundman2020 wrote:Don't go too dead! Drums in a dead room sound pretty awful, actually. Keep some life in the room, or it will feel unnatural, and you won't enjoy your drumming.
Okay will do. Chances are I wouldn't be able to deaden it completely anyway, the absorbion material would probably need to fill the room
I'd like to be able to record demos in there if I can, and it is too small to get any kind of good reflections, that is why I wanted to deaden it. But yeah, a little bit is fine. Also I will likely be using headphones most of the time (with kit mic'd up) so I would add ambience on my mixer, kit always souds better that way unless I'm in a good room.Will let you know as soon as sound test is done. In the meantime I posted the latest schematic of the room in my previous post, be interested to get your comments. It is probably smaller than you imagined, that door is just in an annoying place. I did breifly think of making that door open into the room, but I didn't want to have to go through the practise room to take things in and out of the garage, plus it'd mean having 3 doors.
Best I can do is put down a large rubber mat or something.