Room acoustics - would a curved ceiling cause sonic issues?

[headwerkn]

Hi all,

My lady and I have decided to build our 'dream house' and are looking at using the modular RAL kit home system - RAL HOMES - Ral 2 and Ral 3. Kinda looks like what we were supposed to be living in on the Moon 30 years ago, but anyway... eventually I would build my own personal studio/music den - detached from the main house - using the same system, in a simple tunnel design ,or what they refer to as the RAL Retreat.

Basically it gives you a 6.3m by 3m arched internal shape, insulated and lined with plywood, and I'm curious what kind of issues this would cause sound-wise. Assuming the dividing wall between recording space and control room was not perpendicular to the tunnel itself, theoretically you wouldn't have any issues with standing waves, right? Would the decreasing ceiling height towards either side of the tunnel require heavy trapping?

I'm hoping to visit a similarly constructed house soon, but if anyone versed in acoustic spaces could offer their opinion, I'd really appreciate it.

Cheers, Ben.

[joelpatterson]

I would guess you'd get a pretty specific style of reverb with this design, the RAL folks could probably even tell you what it was. Reminds me of little mountain churchouses I've recorded in, sloping ceilings (although not so half round precisely.) Might be totally awesome for just one acoustic guitar.

[headwerkn]

I'd prefer a live-ish sounding room, so that would be a good thing... go with a timber floor and use rugs, gobos and foam panels/traps near the drum kit etc. to control unwanted reflections.

One possible issue is that each end of the 'tunnel' is a basically a big wall-to-ceiling window. I'm figuring the ability to hang that really heavy sound absorbing material as a giant curtain will solve any reflection issues, particularly in the control room. For the most part I want to enjoy the views though.

[Clueless]

Originally Posted by headwerkn

Hi all,

Basically it gives you a 6.3m by 3m arched internal shape, insulated and lined with plywood, and I'm curious what kind of issues this would cause sound-wise. Assuming the dividing wall between recording space and control room was not perpendicular to the tunnel itself, theoretically you wouldn't have any issues with standing waves, right? Would the decreasing ceiling height towards either side of the tunnel require heavy trapping?

The only thing worse than a standing wave in a room is a focused standing wave. To my eyes, that arched shape will give you an even more perfect(ly bad) modal response than a flat ceiling. The only thing worse would be to live in a dome rather than an arch.

Now, for a single monophonic instrument, like the human voice, you might get some cool effects if the arch were, say, 150' in diameter. But a 10' radius? I don't think so.

M

[lasso]

you'll definitely have an acoustic headache in there. We're talking false ceiling probably.

I have a slight curve to my control room ceiling, nowhere near as much as that - and let me tell you, before I put a fiber glass cloud up - covering almost all of the ceiling - it was modal madness.

It looks very cool though!!! Good luck with but prepare to spend some serious time and maybe money as well making it sound acceptable.

What's the roof made of? The harder the surface the worse sound.

[Disjointed]

ill agree with clueless.. ive been to a couple of places (a mall for instance) that had a dome above a certain point causing all sound from that point to come right back at it.. a great effect, but probably unwanted for a recording situation..

but it seems the point here would be a line down the center of the room on the floor..
you might be able to get a decent sound with a lot of absorption, and try to avoid dead-center sound sources..

+ But the Ral homes look pretty sweet .. i was looking at dome kits before we built or traditional house

[YZ!]

The acoustic problems of such an arched structure could be tamed a bit by a drop ceiling, reducing the interior height to about 2.4 meters; such drop ceiling should be constructed as a bass absorber.

Treating the rest of the surfaces with a mix of diffusers and absorbers is advised.

But there are more experienced people than me here at GS that may provide better information.

[lowfreq33]

You'll definitely need to alter the interior to get a decent sound.

[jwl]

That could be a VERY interesting sound, actually. I'm sure you could mitigate the negatives with acoustic treatment.

What will happen is that the curved ceiling will aim reflections to one spot in the room... a line down the center of the "tunnel," most likely. The trick is going to be placement within the room. You probably won't want to put microphones or whatever it is you are recording on that imaginary center line.... or maybe you will. Who knows. Would sound.....different.

Some friends of mine live in a yurt, a round structure with a sloped ceiling. It's cool because it has high ceilings, and the ceiling reflects sound to the very center of the yurt. You can use these reflections to your advantage with room mic placement. Additionally, the walls of a yurt are not massive, so low end goes right through; you don't have the low end room modes to deal with as it's basically a non-room from the low end's point of view.

Very interesting sound indeed....

[bpape]

I'd agree to stay away from the arch. It will definitely focus as has been discussed earlier.

Now, if you want to have a nice look, a little live, and get rid of the problem, consider filling with absorbtion and building a slatted wood ceiling with variable width slats and spaces. This will act as a wider band Helmholz resonator and give you some good bass control while mitigating the arch isses in the mids and highs - but not killing the sound too much.

Bryan

[lowfreq33]

Look up Avatar Studios (formerly Power Station).