Do room acoustics influence sound that leaks to neighbors?

[Rubberducky]

In a hypothectical case, say you have a room that has certain room acoustics. Will the sound spectrum that leaks to your neighbors be impact by the room? If there is a resonance at 60 Hz, for example, would the sound on the other side of the wall have this same peak?

Or is the sound that leaks completely independent of the room, and only defined by the sound that leaves the speaker and the thickness / material of the wall?

 

[DVDdoug]

If there is a resonance at 60 Hz, for example, would the sound on the other side of the wall have this same peak?

Yes, and (as you probably know) bass goes-through walls better than mid & high frequencies.

If you have bass traps or EQ to tame be bass, it will be better on both sides.

The main thing for "soundproofing" is dense walls and isolation (with the walls on both sides screwed/nailed to a separate set of studs, etc.) and if you want to go all-out and make a studio, also isolated floors & ceilings and sometimes "a room within a room", and all of the air leaks sealed. Soundproofing is construction & architecture, not "treatment".

 

[bachatero]

room modes (resonances) occur due to the walls literally flexing, just like you can see in the classic science demo of a singer/speaker shattering a wine glass. that means you will be able to hear resonances on the other side because on that other side, despite there potentially not existing another resonance, the wall can act like a speaker due to its flexing. or, at least, that's what should happen in theory.

Yes, and (as you probably know) bass goes-through walls better than mid & high frequencies.

although this is true, wouldn't resonances just exacerbate this?

 

[LevityProject]

This is the math behind what is happening when a neighbour hears bass booming from next door, but not much of the higher frequencies.

The wavelength of sound can be found by dividing the speed of sound (1,130 feet / second) by the frequency we need to find the wavelength of. For deep bass like 40hz, Divide 1,130 by 40 = 28 .25 feet. Therefore, a 40 Hz. wave is 28.25 feet long. This sort of illustrates ...

This means that without broadband absorption behind the walls and ceiling, bass can easily pass through into the open air outside, especially if it has a high amplitude. At lower amplitudes, the sound will be less noticable as it travells. This is different than bass trapping for room acoustics ... this would be insulating the room behind the drywall with broadband absorption insulation like Rockwool instead of the standard pink insulation.

 

[Waxx]

The best isolation i witnessed (25 years ago) is rammed earth (a mixture of sand and clay), or rammer earth mixed with straw. It's also a very good absorber, heat isolation/thermal mass and humidity regulator btw. The disadvantage is that it needs to be thick to be stable and hard to make mechanised (a lot of handwork) and you need to protect it against rain when it's an outside wall with a waterproof layer of other material (lime plaster in the place where i saw it. And it's not structural strong, you need a frame of wood, concrete or steel to support it.

I've recorded some Morrocon Zenati folk music in a rammed earth house in the east of Morroco, and altough the room was not acoustic treated at all, it was a very good acoustic, and little eq was the only processing needed That was certainly partly because of very good musicians who always play unamplified and balance themselves, but certainly also because of the room acoustics (wood ceiling, rammed earth floor and walls with little windows with no glass). Even with that no glass, the noise from the village was much damped inside, in a matter it did not disturb the recording. That room was better than most recording studio's i've been in (and i've been in good ones). That cd did sell well in the region and bordering region of Algeria (that has a similar Zenati Berber culture).

But to implent that here, is a bit difficult. What i learned there is that you need enough mass to damp low vibrations, and a porous surface that is also solid to absorb high. I'm not a physician or achemist who can make the right stuff and apply it perfectly right, but i can easely see if material has good specs to damp or not and what should be enough to do the job roughly.

 

[LevityProject]

But to implent that here, is a bit difficult. What i learned there is that you need enough mass to damp low vibrations, and a porous surface that is also solid to absorb high. I'm not a physician or achemist who can make the right stuff and apply it perfectly right, but i can easely see if material has good specs to damp or not and what should be enough to do the job roughly.

That's really cool about recording in Morocco in a rammed earth house. I helped to build something similar in Kenya a number of years ago. I was suprised at how thick and solid walls made of packed mud and straw can be.

In Canada and the US, Rockwool like Roxul Safe n Sound would be the most readily available option for soundproofing a listening room to prevent sound from leaking out of the room. This is what I used for soundproofing between floors in one house. It worked very well

 

[voodooless]

room modes (resonances) occur due to the walls literally flexing, just like you can see in the classic science demo of a singer/speaker shattering a wine glass.

That is incorrect. Flexing walls would imply that energy is actually dissipated into the walls; converted to heat, just like in a bass trap. Room modes are the opposite: they happen because the room walls are very good reflectors of low frequencies, confining the sound waves, making them overlap, and thus form constructive and destructive peaks and valleys in the frequency response depending on the room layout.

If you want to geek out:

In-Room Speaker Frequency Response Simulation (Low Frequency)

[Edit] Member edechamps has pointed out my method of modeling wall absorption was incorrect and he is right. I have replaced the attached ZIP archive with update the Mathematica and Jupyter notebooks. With the old method, the wall absorption was much higher than they should be, and the updated...

www.audiosciencereview.com

 

[Soandso]

Room modes are the opposite: they happen because the room walls are very good reflectors of low frequencies, confining the sound waves, making them overlap, and thus form constructive and destructive peaks and valleys in the frequency response depending on the room layout.

Now I know why I find disturbing long exposure of even normal sounds of daily life, let alone poor fidelity music, inside concrete block rooms with smooth stucco walls and10 foot ceilings.

 

[Waxx]

Modern buildings are build with very little attention to acoustics. It's only in higher end designs that it's really a consideration i think, while it has a huge impact on the quality of life. Even in offices that is the case. I used to work in a smaller bank (as consultant) and the acoustics of their offices were so terrible that i started to work from the server room, because the noise of those was less annoying than the auditive mess in the offices that were very reverberant..

Now i work in a scientific institute (depending on the Universaty of Gent) in a brand new hi end building, and the acoustics are very damped and well done, so the noise that collegues make are minimal intrusive and i can work way more efficient...