15 Feb Home and Project Studio FAQ
We get a lot of inquiries regarding studio design in homes, garages, apartments and condos. Most people involved in building a project studio don’t have a lot of spare cash to hire acoustical consultants, especially when we’ll just have to tell them all the things that can’t be achieved in the limiting environment of existing residential construction. No one wants to pay for bad news. Unfortunately, bad news is often what we have for a project studio owner, especially when it comes to noise isolation questions. What we’ve decided to do is assemble many of the standard questions about project studios, and package all the bad news for free so at least you won’t have to pay for it.
I want to build a studio in my basement, can I build it so that my wife and my neighbours won’t hear anything?
Building a studio space in existing residential construction severely limits the amount of sound isolation that can be achieved. Wood frame construction is difficult to isolate because of its light weight, and connectedness. You can’t start separating the structural sound paths without having your house fall down. Even isolated ceilings and isolated inner walls, which may achieve STC ratings over 50, do not provide significant attenuation below 125Hz. For this you need mass, concrete would be a start, but depleted uranium or solid lead would be better, and not much more impractical than trying to pour concrete walls and ceilings in place in a basement (or living room). Even concrete walls and floors need additional attention. You have to shield the concrete structure from a loud sound source by building an isolated wall. Once the sound energy enters the concrete building structure, it will travel throughout all the walls and floors. This shielded and isolated construction rapidly erodes ceiling height and floor space, and costs a bunch.
Can I use fibreglass insulation to stop the sound getting out of my studio?
There is a big difference between sound isolation and sound absorption. Sound isolation is achieved with a massive construction, or stiff construction and a large airspace, combined with elimination of all structural connections that will pass sound. Rigid yellow fibreglass insulation is an effective absorber of sound when placed against a rigid surface, but does not block sound that would have travelled through that rigid surface (your gypsum board wall, or a plywood floor). Fibreglass is very lightweight, and has negligible sound isolation properties. It will reduce the reverberant energy in the treated room, which reduces the overall sound energy available to worm its way out of the room, but other than the reduction in source level, this would result in a microscopic improvement in sound isolation to other rooms. Rigid fibreglass insulation (4.5 pounds per cubic foot) is also only effective in the midrange and high frequencies. 1″ thick fibreglass is effective down to 1000Hz, 2″ thick fibreglass almost to 500Hz, and 4″ thick fibreglass down to 250Hz. Think of the absorption characteristics as being similar to a high frequency shelving control with an adjustable corner frequency, and about 10dB of attenuation. Oh, and both white and blue styrofoam insulation are of no benefit for sound absorption or isolation, but they might help keep the place warm.
Should I line all my studio and control room walls with fibreglass?
Well, not unless you want to provide a very dead environment with a weird frequency balance. If you made the room completely “fuzzy” by lining it all with absorption, you would effectively kill all of the reflections, and high frequency reverb, but you don’t significantly affect the modal response in the room below 300-400Hz. This leaves the room sounding “wooly”, or “woofy”, lots of low rumbly voice and music, with no top end liveliness. It’s important to balance absorption with diffusion so that you have a room that sounds balanced and pleasant, without having distinct wall reflections that add colouration. You can buy commercially manufactured quadratic residue diffusers, or find the details of construction for your own use in the Howard Sams Publication;”The Handbook for Sound Engineers” by Glen Ballou. If you don’t own this book, you should, even though it seems like a lot of money; it has a lot of answers to questions on both rooms and electronics.
I have a window in my studio space, how can I stop traffic noise coming in?
Brick it in, or cover it up with substantial wall construction, it is extremely difficult to get better than 40dB of midband attenuation from elaborate and expensive window construction details, and they provide even less attenuation in the low frequencies. If you want sound isolation (inward or outward) make it a solid wall. Sorry, you can’t cheat the laws of physics.
I live in an apartment, can I put a floating platform in my living room for my drums to sit on so that I won’t bother my neighbours?
No, forget that; your neighbours will string you up by your drumskin. You would need to have a fully isolated drum room, much like an industrial control booth,or audiometric testing booth, to avoid violent confrontations with your neighbours. On the other hand, a floating platform may work to reduce vibrations transmitted to your neighbours if you happen to own an electronic drum kit instead.
Should I use those nifty sculpted foam absorbers instead of fibreglass panels?
No doubt about it, those sculpted foam absorber panels are way cooler looking than fibreglass, and they don’t make you itch, and don’t shed fibres, but dollar for dollar, you can’t beat rigid coated fibreglass ductliner, or rigid yellow fibreglass for sound absorption. 2″ thick black faced fibreglass ductliner is under $1/sq. ft., whereas the foam is much more expensive. Both materials achieve almost 99% absorption in their respective bandwidths, and the absorption bandwidths are related to thickness of the panels in both materials (1″ for 1000Hz+, 2″ for 500Hz+ and 4″ for 250Hz+). The fibreglass panels can be covered with an open weave fabric (test it by breathing through it) to keep them itch-less and make them more attractive. The rigid coated ductliner costs more than rigid yellow fibreglass, but does not shed fibres as easily, it’s a good investment. If it’s absorption you need and don’t have a big budget, go fibreglass. If you want the cool looks, buy the foam. Keep in mind that not all foam materials are fire rated when applied directly on the walls.
Can I fill my walls full of sand to improve sound isolation?
Well, strictly from an acoustical point of view, it could improve things, but dry sand weighs quite a bit, and gypsum or plaster walls would not contain that much weight for long before bursting. You would also have a problem supporting the extra weight without additional structural support in the footings, beams and joists. If you’re serious about that kind of wall construction, you better do the research, and apply for a building permit, just to make sure that your building doesn’t collapse around your studio walls.
Where can I get more information on design and construction of a “home” sound studio?
While we are not offering any endorsement or warrantee, a good place to start is a book titled: “How to Build a Small Budget Recording Studio from Scratch… with 12 Tested Designs (Third Edition)”, by F. Alton Everest and Mike Shea, published by McGraw-Hill (ISBN 0-07-138700-5).