jj@rabbit.UUCP (07/08/83)
<Enter sarcasm mode> I'm a bit surprised that the difference between heat (i.e. molecular motion) and sound (also molecular motion) is such that what will affect one will not affect the other. It's been my experience that the fiberglass batts in the anechoic chamber I work in here in Murray Hill do an absolutely wonderful job of sound absorption, somewhere around 60-80dB worth, depending on whether you're talking about reflection or transmission, and depending somewhat on what frequencies you are considering. <Exit sarcasm mode> As far as supressing sound transmission through walls, there are a number of solutions, each serving to supress one particular type of transmission. Fiberglass batts in the wall will supress sound transmission in the air paths that are blocked, although rock wool is better <although much more obnoxious/dangerous to work with >. In either case, a piece of insulation about 1.5 times the thickness of the space to be filled (compressed to fit the available space, I can hear the japes right now) will usually eliminate air transmission as a transmission path of any significance. After this path is eliminated, there are still several other paths of transmission, including acoustic to mechanical to acoustic transmission, which is most effective at lower frequencies, and is particularly annoying if a wall happens to resonate near the driving frequencies; <Bass guitar is particularly good at finding such resonances in the usual house.> direct mechanical transmission (footsteps, furniture noises, etc), which are transmitted through the wood framing of the house; and air path transmission through heating/cooling ducts and the like, in which each instance has its own particular characteristic. The solutions to these problems often depends completely on the particular way that the building is constructed. Most of the ways of providing innately good sound insulation in a building also echo the ways to build a rigid and stable structure. Newer methods of construction, such as the use of drywall, plywood flooring, 24" centers, and the like are NOT the way to provide good sound isolation. I will permit the reader to generate her or his own opinion as to their suitability for home construction. rabbit!jj