Triple leaf - at what leaf spacings is it acceptable?

[666666]

I might be forced into a "triple leaf" situation with a room build, but since the leaf spacings are very different, I'm wondering how bad the triple leaf effect will be? In most triple leaf examples published / posted, the leaves are quite close together and often equi-distant.

In my potential situation here, leaf one is about 6" away from leaf two, and leaf two is about 18" away from leaf three. In sum, the spacing between leaves 2 & 3 is three times the distance between leaves 1 & 2.

Am I looking at a serious triple leaf headache here, or are the different spacings, plus the rather wide 18" spacing between leaves 2 & 3, going to perhaps cut down on or eliminate the "triple leaf effect"?

Perhaps it will cause trouble only at very low frequencies? If so, any prediction on what frequency area might be a problem?

Finally, with "triple leaves", there must come a point where the negative effect of triple leaf drops to the point of not being a problem once you reach certain leaf spacings. To exaggerate my point, if leaf one was 12" from leaf 2, and leaf 2 was 15 feet away from leaf three, is this even still considered triple leaf??? Or is it considered double leaf that is 15' from another separate wall??? You see my point. So... at what distances of 3 leaves nullifies the triple leaf effect? If my situation still seems bad, perhaps if I increase the distance of leaf 2 and leaf 3 from 18" to 24" I'll be ok??? Or 36"? Or 48"? Or 8 feet?

I'd rather not get into more details of the situation I am facing right now since there are still too many variables at this point... may not even happen... but I'd like to discuss the triple leaf spacing issue anyway... I've always wondered about it.

[gullfo]

depends. in a voice-over studio on a 40 acre farm, its probably less of an issue than recording death metal bands in a room 2' from an ICU. 3rd leaf is generally bad, but not necessarily as bad as other choices. whichever is the least worst choice, pick that one, and live with the other.

[bpape]

The difference in your scenario and the one (extreme) that you postulated is that in the 2nd one, there would still only be 2 leaves between rooms. In your case, there will be 3. There will be a frequency where it becomes an issue. at 12" it'll be relatively low but still may be a problem depending on your situation.

Bryan

[avare]

The frequency of the space is based upon the square root of the mass of walls and the space in between. The isolation of walls is based upon the the depth and mass. You put a leaf in between and you making two smaller mass-air-mass systems inter-connected and raising the frequency of resonance by half an octave.

With the system you are talking about, the single resonance of the greater distance will be two thirds of an octave below the smaller space. Not insignificant. It usually is considered insignificant with quadruple leaf systems between across the corridor hotel rooms.

More specifics are needed to give you good advice for you application. How thick are the current walls? How much are willing to spend to add mass? These are just starters.

Andre

[naethoven]

Andre,
Hey there, I've been wondering about the "when does it no longer act as a triple leaf anymore? question, too. Starting with the outside walls of a building, you have 2 leaves there, then another set of 2 dividing the CR and Live room, then the other 2 on the other perimeter wall to the outside. How does the sum of 2 of the walls not add up to producing the same effect as triple leaf if, for example, I am standing in the Live room and a sound impinges on the outside CR wall, then the dividing wall, then to me? Why is it negligible if there are 4 leaves? Just wondering.

-Nathan

[nosebleedaudio]

Originally Posted by naethoven

Andre,
Hey there, I've been wondering about the "when does it no longer act as a triple leaf anymore? question, too. Starting with the outside walls of a building, you have 2 leaves there, then another set of 2 dividing the CR and Live room, then the other 2 on the other perimeter wall to the outside. How does the sum of 2 of the walls not add up to producing the same effect as triple leaf if, for example, I am standing in the Live room and a sound impinges on the outside CR wall, then the dividing wall, then to me? Why is it negligible if there are 4 leaves? Just wondering.

-Nathan

Are you talking about several feet between them? Like a hallway between 2 walls?
In this case it is VERY good..

[naethoven]

I just mean the walls of 2 adjacent rooms. If I'm in one room, there is the wall that divides the 2 rooms, then there is the outer wall on the other side of the room I am NOT in. How do those 2 walls not act as leaves? Say both rooms are 15 ft wide.

[avare]

Originally Posted by naethoven

I just mean the walls of 2 adjacent rooms. If I'm in one room, there is the wall that divides the 2 rooms, then there is the outer wall on the other side of the room I am NOT in. How do those 2 walls not act as leaves? Say both rooms are 15 ft wide.

Give specifics, including dimensions and leaf descriptions. You should know better by now. Keith gave a good example of where it is no longer considered important.

Andre

[naethoven]

just pulled up this old thread to reread as I am designing my space. Anyone have more detailed scientific knowledge to add? Andre?

[andrebrito]

That depends on the mass of each leaf but space in air cavity as important to define the ressonant frequencies of the system. If the space between each leaf is high (let's say at least 3-4 inches) then using a trip leaf will give actually better sound insulation due to the additional mass. I presume that is not the case so I would stick with a double leaf system

[naethoven]

Originally Posted by andrebrito

If the space between each leaf is high (let's say at least 3-4 inches) then using a trip leaf will give actually better sound insulation due to the additional mass.

Andre, did you mean feet here? 3-4" is the width of a 2X4, and that is the scenario every source I know gives as a no-no. ??????


P.S. So, basically, if my bathroom is 4ft wide there's no way it would cause a triple leaf w the walls of the neighboring rooms. Correct?