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Sound-proofing rooms: responses

I am grateful for the useful responses to my question about sound-proofing a
room that was not initially designed for that purpose. Since the responses
overlapped in principle, but not in the practical advice offered, I thought
that a summary might come in handy for some of you.
****************
Date: 6 Nov 1996 08:34:15 U
From: Robert Majors <Robert_Majors@llc.washington.edu>

Michael,

How to Build a Recording Studio on a Budget by F. Alton Everest.  Jeff Cooper
has a good book, but is out of print and I can't get even a used copy.
Acoustic Systems for voiceover booths, doors, and the like.

Bob Majors
****************
From: Zacharov Nick NRC/Tre <Nick.Zacharov@research.nokia.com>
Date: Wed, 06 Nov 1996 17:13:31 +0200

Hi

Gypsum, the material manufacturer have a very good practical application
guide for how to obtain certain sound isolation levels using different
constructions. Contact them directly for this book on acoustics isolation.
This is very sound info, to begin with

rgds
Nick Zacharov

Speech & Audio systems
PO Box 100               Tel +358-3-272-5786
33720 Tampere            Fax +358-3-272-5899
FINLAND             email: nick.zacharov@research.nokia.com
**********************
Date: Wed, 6 Nov 1996 11:23:50 -0500
To: kubovy@virginia.edu
From: Biao Tian PhD <biao@ln.nimh.nih.gov>
Subject: Re: Re sound-proofing rooms

Michael,

You can try

Attn. Michael Binns
Acoustical Solutions, Inc
2720 Enterprise Parkway
Suite 101
Richmond, VA 23294-6340
Tel: (804) 346-8350 (800) 782-5742
Fax: (804) 346-8808

They sell a variety of materials for acoustic insulation.

Good luck

Biao

Biao Tian Ph.D.
Georgetown University Medical Center
Institute for Cognitive and Computational Sciences
New Research Bldg, WP22A
3970 Reservoir Rd. NW
Washington, DC 20007-2197
USA

Phone: (202) 687-6438
Fax: (202) 687-0617
E-mail: biao@ln.nimh.nih.gov
*************************
From: "Steven M. Boker" <sboker@calliope.psych.nd.edu>
Date: Wed,  6 Nov 96 11:29:26 -0500

Hi Michael-

The answer will depend on the SPL, frequency spectrum and your
criteria for success.

The simple answer goes like this.  There are several variables you
can affect which will have different outcomes.  I have listed them
in descending order of importance.  These are also nested: if you
haven't addressed higher priority items, there is no point in addressing
lower priority items.

1. Air tight inner seal.  The room must be as near to being air-tight
   as possible.  Leakage from around doors, under walls, through air
   ducts, through electrical outlets, through light fixtures and
   switches, or any other hole in the inner seal will constitute
   the main source of acoustic transmission in most normal rooms.
   Imagine the room as a ballon that is being inflated and deflated
   thousands of times per second.  If there are holes in the ballon,
   the sound pressure equalizes with the outside, thereby transmitting
   acoustic energy.

2. Rigid mass on inner walls.  Once again think of the room as a
   balloon being inflated and deflated.  The more the room's walls
   expand and contract, the more acoustic energy is transmitted
   to the air on the exterior surface of the wall.

3. Air tight, acoustically isolated outer seal.  A outer layer
   to the room which is not connected to the inner layer by
   structural components, creates sort of an outer balloon around
   the inner balloon.  The much reduced SPL at the surface of the
   inner wall is once again attenuated by the outer wall.

4. Rigid mass on the outer walls.

5. Repeat as needed.

Some effect can be obtained by materials that attempt to absorb
acoustic energy.  Thus, after assuring yourself that the booth is
airtight, covering the booth inside and out with acoustic
foam (Markertech 800-522-2025) can help attenuate high frequency
components.  These materials will have little effect on low frequency
components.  Also, these will alter the acoustic characteristics
of the interior of the booth (if that is of concern).

Your best bet for real isolation is to build a small airtight room
around the isolation booth using conventional frame and 5/8"
sheetrock on both the inner and outer surfaces.  Fill the space
between the studs with fiberglas insulation to reduce standing
waves.

Good luck!

Steve

---
 Steven M. Boker                                 219-631-4941 (voice)
 sboker@nd.edu                                   219-631-8883 (fax)
 http://www.nd.edu/~sboker/                      219-257-2956 (home)
 Dept. of Psychology, University of Notre Dame, Notre Dame, IN 46556
**************************
Date: Wed, 06 Nov 1996 09:45:09 -0600
From: Fred Wightman <WIGHTMAN@waisman.wisc.edu>

Michael:

I've gone through similar thought processes lately. There aren't any good
books, but the basic principles are simple.

For isolation, think MASS! Put extra drywall on the walls on independent
studs. Also, the door and its seal are VERY important. Call Industrial
Acoustics in NY, talk to Ellis Singer 718-430-4531. They make excellent
doors and seals. Put money there...the walls and ceiling you can do yourself.

Fred Wightman
****************************
Thanks again,
|\    /|  / Michael Kubovy, Professor of Psychology
| \  / | /  Dept. of Psychology, Univ. of Virginia, Gilmer Hall
|  \/  |/   Charlottesville, VA 22903-2477
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