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Author Topic: Are acoustics louder from a ground floor or upstairs apartment?  (Read 404 times)

Offline thedoc

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Chas B. Jr asked the Naked Scientists:
   question: Is the acoustics louder coming from an up stairs apartment, as opposed to a lower unit? (given that the sound is identical).
What do you think?
« Last Edit: 29/07/2016 11:40:49 by evan_au »


 

Offline timey

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Chas B. Jr asked the Naked Scientists:
   question: Is the acoustics louder coming from an up stairs apartment, as opposed to a lower unit? (given that the sound is identical).
What do you think?

Well it would rather be dependent on where the listener was situated, of course, but as a more general consideration:

There will be a slightly different  air pressure in, and around a more lofty apartment.  The air will be less dense than apartments below it and a pressure wave of sound will meet slightly less resistance and travel further.
Also an apartment that has a hollow space, (ie: another apartment) below it, will not contain sound in the same way that an apartment on the ground floor would.

In an apartment where one's floor is the person below's ceiling, raising loud speakers off the floor on stands, and placing several layers of carpet underlay under the base unit can vastly improve neighbourly relations.
« Last Edit: 29/07/2016 12:47:00 by timey »
 

Offline timey

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Chas B. Jr asked the Naked Scientists:
   question: Is the acoustics louder coming from an up stairs apartment, as opposed to a lower unit? (given that the sound is identical).
What do you think?

Well it would rather be dependent on where the listener was situated, of course, but as a more general consideration:

There will be a slightly different  air pressure in, and around a more lofty apartment.  The air will be less dense than apartments below it and a pressure wave of sound will meet slightly less resistance and travel further.
Also an apartment that has a hollow space, (ie: another apartment) below it, will not contain sound in the same way that an apartment on the ground floor would.

In an apartment where one's floor is the person below's ceiling, raising loud speakers off the floor on stands, and placing several layers of carpet underlay under the base unit can vastly improve neighbourly relations.
After a little more thought, I realise that I have posted in error.

These effects really are minimal, but it is important to be precise.

Sound will travel faster in denser air, and denser air will be found closer to the ground.
Sound will travel further if it meets less resistance, ie: walls, trees, etc, therefore it will travel further higher up, where these things are not.

But...a building has a NPP (natural pressure plane).  It you are above this NPP, with the windows closed, the air in your apartment will be less dense than outside, but more pressurised.  Although the air is warmer and less dense, the pressure is pushing this less dense air together more tightly.  A sound wave will travel faster.  (edit: but will have a higher absorption rate in the higher pressure environment, and will not travel as far.)

But if you reduce both the air density and the air pressure to the extent of the vacuum of space, a sound wave has no medium to propagate in...

Although:

https://www.newscientist.com/article/mg20827804-600-sound-can-leap-across-a-vacuum-after-all/

I do realise I'm heading off on a tangent now...(chuckle)
« Last Edit: 29/07/2016 17:26:17 by timey »
 

Offline evan_au

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Perhaps the question is asking "Which will I hear more clearly: People walking around in the apartment above me, or the people walking around in the apartment below me?".

It depends on the floor construction, and whether carpet is installed, but I suggest that footsteps in the upstairs apartment will be more audible because:
- The vibration of steps in the apartment upstairs will be coupled directly into the floor upstairs, and will be conducted to the ceiling above your head, where a small amount of the energy will transfer into sound in your apartment. It is a small amount because of the considerable impedance mismatch between the air and the flooring material.
- The vibration of steps in the apartment downstairs will be coupled directly into the floor downstairs; a small amount of the energy will transfer into sound in the apartment below. A small fraction of this will couple into the floor below your apartment, and a small fraction of this will couple into the air of your apartment.

So I suggest that sound of footsteps from the apartment above you will be more audible than the sound of footsteps below you, as there is an extra barrier in the way of footsteps from the apartment below (all other things being equal).
 

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