*
Ok,
I’m approaching the drywall phase of the addition. Our window rep made an interesting comment that I’m hoping to get verified.
He said that if you use 1/2″ on one side of a wall (Internal walls that is) and 5/8 on he other, you don’t get noise enhancement by vibraion. Using the same thickness makes for a tuning fork effect. This is part of why plaster walls were quieter. Uneven thickness.
So –
Whaddaya think?
Peter
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*
Correct
*I worked at recording studio and we used that same theory to sound proof a window into the sound room. We also tilted the glass at slightly different angles.
*Sounds kinda voodoo-ish and hocus pocus to me, and what do you do about door jamb thickness? Special order the doors? I am not discounting this completely though, after all I didn't believe that business about divining rods and water witching until I had it proven to me first hand.
*Personally I wouldn't put much stock in that theory unless I could see data to support it. Have to agree with Mark, Wouldn't the extra 1/8" from using 5/8 DW on one side cause some problems when it comes to casing the doorjambs?Scott R.
*The idea that is based on is not hocus pocus--it's called sympathetic vibration. Tune two guitar strings so they produce the same note, and pluck one--the other will start to vibrate as well, (but not the other strings on the guitar) because the ratio of mass to energy would be the same for those two strings, and thus they both pick up/transmit the same frequency of sound waves.However a wall cavity is more like a snare drum--tap one membrane, and the force of the air trapped inside will cause the other membrane to move as well. In this case it doesn't much matter if the two membranes differ in mass/density--they still affect each other.It would still be interesting to use a decibel meter to test this idea, but I imagine any noise reduction by two thicknesses of drywall would be quite minimal. I would imagine that plaster walls were quieter because of differences in density and compostion, rather than thickness. Actually, by the very nature of its construction, drywall should be a comparatively good conductor of sound.
*Most of the transmittion is not by harmonics or through the air space but via the solids - the studs which contact both surfcae solids. That is why most party walls use staggered stud layouts.If you wanted to test this theory though, you could get the same effect by using regular 1/2" on one side and a denser typr like MR on the other side for differing masses with same thichness so you don't haver the dimensional problem at jambs. Most sound resistant walls will require greater thickness.One I just completed was SR over 1/2" homasote over 2.5" studs with 2" foam in the cavity. Available design space didn't allow a thicker wall. The clients were impressed with the results. (Bathroom near main entertainment areas of house required no shower or flush noises to penetrate)
*Ok, The guitar analogy kinda helped for me. I guess I'll buy it now. Still, the problem of the different thickness and door jambs concerns me. Perhaps if you used 3/8 on one side and 5/8 on the other?
*I have found, through experimentation with my sister and her brood, that any soundproofing that restricts children from the room works swell, any that does not, fails horribly.Don
*
Ok,
I'm approaching the drywall phase of the addition. Our window rep made an interesting comment that I'm hoping to get verified.
He said that if you use 1/2" on one side of a wall (Internal walls that is) and 5/8 on he other, you don't get noise enhancement by vibraion. Using the same thickness makes for a tuning fork effect. This is part of why plaster walls were quieter. Uneven thickness.
So -
Whaddaya think?
Peter