I just heard another av guy talking about how constructing a theater room with metal studs is better for keeping the sound inside the room. This doesn't make much sense to me, I recommend offset studs built on a 2x6 top and bottom, it always helps, and I can understand WHY it makes a difference.

Can someone explain (or disprove) why metal studs would make a more isolated room than wood studs?

I'm thinking this is what's known as a good fairy tale, blowing smoke, or just plain BS......lol

might fall under trunk slammin jive

It is also best to place your speakers with the drivers facing into the wall, not into the room. ;)

It only works better if they use beer cans for insulation!!! ;-)

The only guess I could venture would be vibrations of the metal vs. the wood, but it sounds like hogwash to me.

Hmm...Stud vibration...that outta add to the high fidelity. I'm sure we can get the studs THX rated like everything else?? =]

I tried to figure this out once, and came to the conclusion that metal studs and wood studs are pretty much the same in strength, but the wood will transmit slightly less sound.

Double walls improve the attenuation because there is no mechanism for sound to be coupled directly from one piece of drywall to the other. 2 x 6s improve the attenuation because more mass would have to be moved and because they are less flexible than 2 x 4s. This raises the frequency of any resonance, but a higher more damped resonance is an improvement because of the damping.


Steel studs all by themselves are flimsy, but once they are screwed to drywall on both sides, if the screws are not too far apart, they become rigid. THAT is why they are pretty much the same strength as wood.

The wood is heavier, though, so it will tend to dampen transmission of sound through the wall, just because moving more mass means higher attenuation. There probably is some half of a percent advantage to the wood also because it is slightly irregular in density and strength, so any resonances would have a lower Q, meaning the resonance would be spread out in frequency and not so spiky.

Your friend is quite correct, the metal stud walls do provide more sound dampening than wood.

2x4 stud with 5/8" drywall (2 layers total) and Batt insulation gives you an approximate STC rating of 34 - 39

whereas...

3 5/8" metal studs, 5/8" drywall (2 layers total), Batt insulation gives you an STC rating of about 43 - 44

However you were also correct in that 2x4 offset with insulation is even better, gives you about 46-47 STC rating.

Also adding limp mass barrier, two layers of drywall, resilient channeling and isolation pads all increase the STC rating. (Two layers of Drywall is probably cheapest).

To give you an idea of those numbers and how they relate to sound that you would hear, here is a guideline:

STC
25 Normal Speech Easily Understood
30 Normal Speech Audible, but Unintelligible
35 Loud Speech Understood,
40 Loud Speech Audible, but Unintelligible
45 Loud Speech Barely Audible
50 Shouting Barely Audible
55 Shouting Not Audible

Well, I have some contradicting replies, this was told to a builder by a competitor so I want to be sure to get it right. Anyone know where I can get more info?

I want this builders business and I am not trying to make the other guy look stupid but I do want to know what I am talking about when we discuss the differences.

I can't lay my hands on it but I have read that metal is better than wood for sound isolation. I wouldn't necessarily assume that to mean a better sounding room though. Perhaps a call to RPG or one of the many sound treatment companies would be worthwhile.

Nah, that's a description of me in the jacuzzi tub......lol

A better sounding room, i.e. inside the room, relates to a room's Noise Reduction Coefficient and its Noise Criteria not the Sound Transmission Class. The STC rating relates to a partitions ability to pass sound and therefore how sound is heard outside the room.

NRC is how a room, or surface more accurately, absorbs or reflects sounds across a set number of frequencies and numbered from 0 to 1, zero being total reflection, one being total absorbtion.

NC is a measurement of the room's mechanical noise, i.e. are there AC ducts whirring or toilets flushing etc. the lower the NC rating the better.

NFI is of course the lack of interest you are all now displaying. I'll try to be shorter next time...promise (_!_)

Yup, I got that NFI thing pretty good about now.....lol

This line was fed regarding the sound levels outside the room being reduced.