Perforating my ceiling with holes?

Timur Born · 16th July 2008

Hey there!

Could someone tell me what acoustical effect I will get by perforating my "second" ceiling with holes?

My room has an original height of 3.3 m and is made of wood construction (build around 1910 or so). But the ceiling got lowered to 2.8 m (before I moved in) with a closed construction of either simple chipboard or plasterboard. The room in between is most likely not filled with anything but air.

Now I'm wondering if I cannot make use of that additional space to get rid of some reflections and resonances without rebuilding my whole room? Would drilling lots and lots and lots of holes into it have any benefitial effect?

Glenn Kuras · 16th July 2008

Quote:

Originally Posted by Timur

Hey there!

Could someone tell me what acoustical effect I will get by perforating my "second" ceiling with holes?

My room has an original height of 3.3 m and is made of wood construction (build around 1910 or so). But the ceiling got lowered to 2.8 m (before I moved in) with a closed construction of either simple chipboard or plasterboard. The room in between is most likely not filled with anything but air.

Now I'm wondering if I cannot make use of that additional space to get rid of some reflections and resonances without rebuilding my whole room? Would drilling lots and lots and lots of holes into it have any benefitial effect?

You would need to drill some pretty big holes and at that the math would need to be right. NO IT WILL NOT WORK.

See the following page to understand how diffusion works GIK Acoustics presents "How Diffusion Works!"

Glenn

andrebrito · 16th July 2008

If there's rockwool behind that ceiling, you would turn into an absorber for medium frequencies, with a maximum frequency being setup according to the perforation area of the panel.

But you said there is only air in the cavity so this effect is really diminished and which such air space, it would probably have a peak absorption around 100-200 Hz

The peak for a perforated panel with a 4.5 % open area over a 200 mm cavity is around 200-250 Hz.

Timur Born · 17th July 2008

Thanks for the replies. Using the ceiling as bass trap doesn't sound like such a bad idea after all.

I will start with some corner and wall treatment and see how the room behaves afterwards. If there's still too much bass energy around I might opt for the holes in ceiling trick.

16th July 2008	#1
Timur Born Lives for gear Joined: Mar 2008 Posts: 1,429 Thread Starter	Perforating my ceiling with holes? Hey there! Could someone tell me what acoustical effect I will get by perforating my "second" ceiling with holes? My room has an original height of 3.3 m and is made of wood construction (build around 1910 or so). But the ceiling got lowered to 2.8 m (before I moved in) with a closed construction of either simple chipboard or plasterboard. The room in between is most likely not filled with anything but air. Now I'm wondering if I cannot make use of that additional space to get rid of some reflections and resonances without rebuilding my whole room? Would drilling lots and lots and lots of holes into it have any benefitial effect?

16th July 2008	#3
andrebrito Lives for gear Joined: Jan 2007 Location: Lisbon, Portugal Posts: 998	If there's rockwool behind that ceiling, you would turn into an absorber for medium frequencies, with a maximum frequency being setup according to the perforation area of the panel. But you said there is only air in the cavity so this effect is really diminished and which such air space, it would probably have a peak absorption around 100-200 Hz The peak for a perforated panel with a 4.5 % open area over a 200 mm cavity is around 200-250 Hz. __________________ Singer/Songwriter/Producer/Acoustical Engineer http://www.onlineacoustics.com - Acoustics ! http://www.mel-music.com - project of mine with a female singer http://www.sonicflames.com - Indie Label & Audio/Music Services http://www.spinousmusic.com - my one man band project

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17th July 2008	#4
Timur Born Lives for gear Joined: Mar 2008 Posts: 1,429 Thread Starter	Thanks for the replies. Using the ceiling as bass trap doesn't sound like such a bad idea after all. I will start with some corner and wall treatment and see how the room behaves afterwards. If there's still too much bass energy around I might opt for the holes in ceiling trick.