Gypsum board as low frequency absorber?

Fiftyfifty

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My listening chair is against the rear wall. This results in relatively strong bass at that position, although the bass a little further into the room towards the speakers is more balanced. Someone advised me to use gypsum board on the rear wall. It works! And if I leave an air gap between the board and the concrete wall it works even better. Better than rock wool.

Would like to know if any of you have experience with gypsum boards. Any information on the acoustic properties of gypsum boards will also be useful - does it absorb specific frequencies, etc. And what is the air gap doing?

Thanks
 

bhooshaniyer

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I have done sound proofing for an entire house 15 years back. I would caution you against using materials which have potentially dangerous materials in them. Steel wool is one such and these days it's categorized carcinogenic in the international market but i am sure it's easily available in India. I am not sure about gypsum board but do you lr research. Dont be confused by facts that its available in Indian market or some traders are tauting them but go by the international standards. Good luck on getting good base but pls be mindful of long term cancer risk products.
 

skumar

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My listening chair is against the rear wall. This results in relatively strong bass at that position, although the bass a little further into the room towards the speakers is more balanced. Someone advised me to use gypsum board on the rear wall. It works! And if I leave an air gap between the board and the concrete wall it works even better. Better than rock wool.
This is in contrast with what one of the acoustic professional advised me - "fill the gap between gypusm board and ceiling with rockwool or similar material, the LF waves will be absorbed in this case, rather than hitting the ceiling and refelcting back thru the gypsum boards".
 

Fiftyfifty

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I have done sound proofing for an entire house 15 years back. I would caution you against using materials which have potentially dangerous materials in them. Steel wool is one such and these days it's categorized carcinogenic in the international market but i am sure it's easily available in India. I am not sure about gypsum board but do you lr research. Dont be confused by facts that its available in Indian market or some traders are tauting them but go by the international standards. Good luck on getting good base but pls be mindful of long term cancer risk products.
Words of wisdom indeed! But if gypsum board is carcinogenic, please say so and quote reference. That would be more helpful?
 

reignofchaos

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I have done sound proofing for an entire house 15 years back. I would caution you against using materials which have potentially dangerous materials in them. Steel wool is one such and these days it's categorized carcinogenic in the international market but i am sure it's easily available in India. I am not sure about gypsum board but do you lr research. Dont be confused by facts that its available in Indian market or some traders are tauting them but go by the international standards. Good luck on getting good base but pls be mindful of long term cancer risk products.
Gypsum boards are used for false ceiling work worldwide. I don't think there is cause for concern.
 

keith_correa

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This was thrown up as the first result when I googled. The key word here is "respirable" so I'm not sure how relevant this is for boards. But even so, personally, I would not take a chance and I'd wrap it with a a cloth to prevent particles in the air. IMG_20210803_094545.jpg
 

keith_correa

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Suspect doesn't mean it is proven. There are hundreds of items that are suspected of cancer we use daily with no solid proof.
True. Even repeated inhalation of talcum powder is suspect. I know how we Indians love to smother babies with that stuff. Ugh! But still, personally, I would be wary. Murphy's law catches up eventually.
 

keith_correa

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Not very effective compared to rockwool from what I see. But given the thickness of the mineral wool in that chart...
 

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hpdinesh

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Not very effective compared to rockwool from what I see. But given the thickness of the mineral wool in that chart...
Is this the average of absorption coefficient of entire spectrum or any particular frequency? Because, I'm surprised that the foam has better coefficient than others.
 

Dev.R

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In my music room the false roofing is Gypsum and between the ceiling and false ceiling it is filled with mineral wool, but it didn't do anything good to the sound. Then I added carpet on the floor , which reduced the echo. But only after adding the bass traps on all the four corners and panels on first and second reflection points , I started enjoying the music.
 

shyamv

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My listening chair is against the rear wall. This results in relatively strong bass at that position, although the bass a little further into the room towards the speakers is more balanced. Someone advised me to use gypsum board on the rear wall. It works! And if I leave an air gap between the board and the concrete wall it works even better. Better than rock wool.

Would like to know if any of you have experience with gypsum boards. Any information on the acoustic properties of gypsum boards will also be useful - does it absorb specific frequencies, etc. And what is the air gap doing?

Thanks

Thanks for your observations. I have a similar situation with my listening position against the back wall in a room without any acoustic treatment. Are you looking at absorption for the back wall in addition to front wall ie behind the speakers? Any thoughts on absorption at front vs back wall? Thanks to all for your inputs.
 

Fiftyfifty

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Thanks for your observations. I have a similar situation with my listening position against the back wall in a room without any acoustic treatment. Are you looking at absorption for the back wall in addition to front wall ie behind the speakers? Any thoughts on absorption at front vs back wall? Thanks to all for your inputs.
In my limited view, the untreated front wall can reflect all frequencies and cause a kind of echo/reverberation. An interested back wall will do the same but because it is far from the speakers, that reflection will not impact the sq so much except for low frequencies. As low frequencies have a longer wave length, they tend to accumulate around the back wall, and if you are sitting near there, can result in boominess in that position. A solution would be to move forward 3 feet or so, or treat the back wall with material that absorbs only low frequency. I'm trying the latter option with gypsum board. Experts - need your inputs.
 

panditji

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Why not a Cork sheet? I have been googling anti vibration cork sheets/blocks to put under my Tannoys and discovered they absorb sound well.. You can place a 3 x 2 feet 25 mm thick standard size cork sheet on the wall behind you to absorb sound...May be cover it with a cloth if it doesn't look nice to you...

As an added bonus, while you are listening to music, someone can throw darts at the board behind you...
 

keith_correa

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As an added bonus, while you are listening to music, someone can throw darts at the board behind you...
I like! I like! If you happen to experience this, a video will be most entertaining! :p

From Andrew Jones:
Ceiling reflections are one of the worst. Sidewall reflections can be good, adding to a sense of spaciousness, if the stereo speaker possesses well-controlled directivity. This same sidewall phenomenon happens in concert halls, on a different scale. The tall, narrow, long concert halls -- traditional ones -- were always the best halls. Sidewall reflections are lower-correlation than ceiling or floor, so they add spaciousness. Correlated signals, by contrast, add coloration.
Like I like to do, I'm posting this to just stir the pot and to open up minds having preconceived notions.
 
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chander

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someone can throw darts at the board behind you...
:cool: too cool! If you do this please share a video!

On a more serious note - yes Cork works too, I saw somewhere - maybe pinterest - sound absorption panels made out of wine corks, liked the idea ordered a few 100 wine corks from eBay - the project never took off, but, seems like a nice idea. Cork also looks pretty good (subjectively).

A friend of mine used to use champagne corks as feet for his Yamaha Actives.
 

Fiftyfifty

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I like! I like! If you happen to experience this, a video will be most entertaining! :p

From Andrew Jones:

Like I like to do, I'm posting this to just stir the pot and to open up minds having preconceived notions.
I tend to agree. My music sounds better if i leave the first reflection points unattended.

As for wine bottle corks, I will surely pass out by the time I finish with opening the stuff :)
 

sud98

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Please use the absorption graph across the spectrum and see if its of value. Gypsum boards are not effective for LFE. A half inch board would absorb around .29 at 125Hz. Comparitively mineral fiber would do around 0.78 to 0.9.

The good ones either use a low density, high absorbent material or leave air gaps for the same.
 
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