Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!tektronix!tekid!eda From: eda@tekid.UUCP (Ed Averill) Newsgroups: net.misc Subject: Re: sound insulation Message-ID: <1390@tekid.UUCP> Date: Tue, 12-Jul-83 06:05:53 EDT Article-I.D.: tekid.1390 Posted: Tue Jul 12 06:05:53 1983 Date-Received: Tue, 12-Jul-83 20:10:40 EDT References: ihuxm.333 Lines: 43 This is a real sore spot with me, so I'll pass a bit of info along. There is a real inexpensive way of getting great reduction in sound conduction. It is to use "offset studs". The standard sheetrock wall surfaces are placed on studs that do not connect through the wall. This is most easily done in standard construction with six inch plates at the top and bottom, and with 4 inch studs placed alternately against each edge at intervals to support the size sheetrock in use. The effectiveness comes from the low resonant frequency, and the low Q of a sheetrock resonator. It should be a standard construction technique for seperating sleeping areas from the rest of the house, unless there is some other two-wall barrier like a closet. I also used fiberglass batting on the premise that it would help disperse high frequency noise. My success is so complete that sounds from my living room are perceived to come from the opposite direction in the adjacent bedroom because the hallway leads around to a door there. While this is a standard technique in industrial construction, it took some heavy emphasis to get my home contractor to put it in. The other sound path that is hard to control is ductwork. I suspect that the answer there is massive baffles for low resonance, probably at the center of a star distribution system. This is the significant path for noise from one end of our house to the other. I can understand my 3 year old's requests for potty-help if my head is on the sofa next to the heating duct at the opposite end of the house. The duct has a straight shot through the central distribution point to there. There are good references on this subject in libraries with architecture schools. I have no memory of book titles I have read, but I remember clear discriptions of how to solve the ploblem. The clearest analogy I ever ran into was that of transmission line theory. The energy must be dissapated somewhere, and will be reflected where there is significant impedance mismatch. The logarithmic nature of the ear requires a lot of attenuation to be effective. Good Luck.