What is the best acoustic material to place on the floor?

caesar

Active Member
May 31, 2010
2,933
0
36
#1
Although regular rugs and carpets seem to work, is there a better acoustic material to manage peaks and dips? Why don't people just lay absorption panels on the parts of the floor where one wouldn't walk?
 

mep

Member Sponsor & WBF Founding Member
Apr 21, 2010
9,483
0
0
#2
Although regular rugs and carpets seem to work, is there a better acoustic material to manage peaks and dips? Why don't people just lay absorption panels on the parts of the floor where one wouldn't walk?
What part of the floor would that be?
 
May 30, 2010
13,970
43
48
Portugal
#3
Although regular rugs and carpets seem to work, is there a better acoustic material to manage peaks and dips? Why don't people just lay absorption panels on the parts of the floor where one wouldn't walk?
F. Toole reccomeds a high-quality clipped-pile woven carpets (with porous backing because the sound must be allowed to penetrate into the felt underlay) on a good carpet underlay— 40 oz/sq yd (1.4 kg/m2) hair felt, which is typically about 0.43 in. (11 mm) thick. We should avoid rubber or plastic backed carpets. Sound Reproduction page 478.
 
Apr 3, 2010
16,022
0
0
Seattle, WA
#4
F. Toole reccomeds a high-quality clipped-pile woven carpets (with porous backing because the sound must be allowed to penetrate into the felt underlay) on a good carpet underlay— 40 oz/sq yd (1.4 kg/m2) hair felt, which is typically about 0.43 in. (11 mm) thick. We should avoid rubber or plastic backed carpets. Sound Reproduction page 478.
Indeed. The reason he does that is because the timbre change seems to come at 500 Hz+ so even a thin absorber works.

If you want more data than you ever thought you needed on acoustic properties of carpet and its underlayment, this is a great paper to buy: http://scitation.aip.org/content/asa/journal/jasa/27/6/10.1121/1.1908124

It has nice graphics like this:



We see that with enough thickness, we get pretty good absorption starting at 500 Hz.
 

steve williams

Site Founder, Site Owner, Administrator
#5
Although regular rugs and carpets seem to work, is there a better acoustic material to manage peaks and dips? Why don't people just lay absorption panels on the parts of the floor where one wouldn't walk?
I use an OEM of my acoustician called Noiseout which sits above the subfloor and under the carpet pad

http://noiseout.com/

It converts the floor to a bass trap

you don't even know it's there
 

caesar

Active Member
May 31, 2010
2,933
0
36
#6
Gentlemen, thank you all for the replies. I will check out the "noise out".

But what is unclear to me is: why, theoretically, we need to treat the floor differently than the walls? Why not just have a runner rug going to your rack, and adorn the rest of the floor with absorbers and cool looking RPG diffusors?

My perspective may be different also, as I am playing around with an omni. The manufacturer recommends a lot of highly reflective surfaces, but I have wood floors and wood walls. Placing the speaker on a hardwood floor alone, I have a sinusoidal looking midrange, with a dip in the lower midrange and a peak from 1k to 2k. However, when I place a moderately thick Tibetan rug on the hard wood floor, it's like magic! Measurement flattens out fairly well and the midrange becomes much, much, much cleaner. But this again begs the question, if this type of rug works so well, why not reduce the number of the ugly absorption panels in your living quarters, and hang more beautiful rugs on the walls, as they do in many parts of the world?
 
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Apr 3, 2010
16,022
0
0
Seattle, WA
#7
The reason the floor is different is because the reflections there are heard equally the same by both ears (assuming on axis). The psychoacoustics of that is different than the side walls where one ear will hear the sound differently both in time and tone.

On the walls, you want broadband absorption which should go to 200 to 300 Hz (transition frequencies). That requires at least 4 inches absorber. So the rug there doesn't work as well.
 

steve williams

Site Founder, Site Owner, Administrator
#8
The reason the floor is different is because the reflections there are heard equally the same by both ears (assuming on axis). The psychoacoustics of that is different than the side walls where one ear will hear the sound differently both in time and tone.

On the walls, you want broadband absorption which should go to 200 to 300 Hz (transition frequencies). That requires at least 4 inches absorber. So the rug there doesn't work as well.
I also use an OEM from my acoustician on the side walls called Lumitex which lines my drapes. Lumitex is thin like a piece of fabric but is equivalent to stuffing your walls with 2" of insulation

http://www.soundsense.com/wp-content/uploads/2013/06/Lumitex™.pdf
 

Joe Whip

New Member
Feb 8, 2014
1,099
0
0
Wayne, PA
#9
Personally I use carpets from Turkey or Iran. They work great. Oh yeah, and they look great too. I just can't get things like acoustic foam panels past the wife.
 
Jul 8, 2010
1,232
0
0
70
New Milford, CT
#10
why, theoretically, we need to treat the floor differently than the walls?
From the perspective of taming bass, you would treat a floor just like any other surface. Anechoic chambers need to be anechoic at all frequencies, and they have a fully absorbing floor. The problem in a home is that people walk on the floor. But for places where nobody walks, thick bass traps are very useful. I have a bunch of bass traps straddling the wall-floor corners in my living room home theater, resting half on the floor and half against the walls.

--Ethan
 
Aug 5, 2013
139
0
16
Stockholm Sweden
#12
Although regular rugs and carpets seem to work, is there a better acoustic material to manage peaks and dips? Why don't people just lay absorption panels on the parts of the floor where one wouldn't walk?
View attachment 14196

This is an effective way to treat the floor. These are called flower wings from SMT. The picture is taken at My friends (the Cucumber) listeningroom. I also use these wings on the first reflection on the floor and They really work! Herr is some measurments from another guy (Mctwins) who really like the resultat from the Flower wings. This is in Swedish:
http://www.euphonia-audioforum.se/forums/index.php?s=&showtopic=10565&view=findpost&p=172750

Best regards Krelle
 

JackD201

[WBF Founding Member]
Apr 21, 2010
10,994
8
38
Manila, Philippines
#14
Caesar check out Langerton's website.
 
#16
Carpeted rooms, which I've lived in all my life until last year, are dead sounding. The surface absorbs too much in midrange and highs, and the backing absorbs too little in the bass. The paradoxical effect this has is to make reproduced music sound boomy and steely as well as lacking in presence and atmosphere. "hifi"

I floored my bedrooms and hall with Armstrong Luxe Plank "Best" flooring in Exotic Fruitwood Persimmon and Honey Spice last year, and I love it. But the magic may be in also using the Quiet Comfort Premium Underlayment S-1836, which was nominally made for engineered wood but is also recommended by Armstrong for use under their floating vinyl footing. The underlayment is thin but polyethylene foam based and very dense. The result is wonderful to walk on (more comfortable to walk on in bare feet than carpet because it has just the right amount of high density padding, so you don't sink, but feet have soft impact not unlike real wood but slightly softer, and hiding the awful hard slab underneath) and seems to have marvelous effect on sound, less boom, more presence. Master bedroom stereo (which has Revel M20's and SVS 1646 subwoofer) has never sounded so good.

http://www.armstrong.com/flooring/luxury-vinyl/luxe-plank.asp

http://www.armstrong.com/rtladmin/content/files/43484.pdf

http://brickpoolhouse.blogspot.com/2013/09/pictures-after-remodel.html
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
7,094
25
48
#17
think concert hall.

diffusive walls and ceiling, wood over solid flooring under the sound source, absorbtive listening area.

you want to retain maximum musical energy and then allow it to propigate naturally. once energy is absorbed (near the sound source) there is a tonal shift and you can never recover that energy.

so hardwood floors under the speaker 1/3rd (2/5th) of the length of the room, carpet under the listener 2/3rds (3/5th) of the room.

my room is constructed exactly this way for these reasons.

the wood flooring of choice depends on what is underneath, and if it's concrete, how much hydrostatic pressure is in the ground....and how effective the vapor barrier might be. there are wood products for any application.

and btw, moving speakers around on a hardwood floor with the wood running perpendicular to the length makes life very easy. i can do 1/8th" adjustments easily by myself with 750 pound towers.
 
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#18
think concert hall.

diffusive walls and ceiling, wood over solid flooring under the sound source, absorbtive listening area.

you want to retain maximum musical energy and then allow it to propigate naturally. once energy is absorbed (near the sound source) there is a tonal shift and you can never recover that energy.

so hardwood floors under the speaker 1/3rd (2/5th) of the length of the room, carpet under the listener 2/3rds (3/5th) of the room.

my room is constructed exactly this way for these reasons.

the wood flooring of choice depends on what is underneath, and if it's concrete, how much hydrostatic pressure is in the ground....and how effective the vapor barrier might be. there are wood products for any application.

and btw, moving speakers around on a hardwood floor with the wood running perpendicular to the length makes life very easy. i can do 1/8th" adjustments easily by myself with 750 pound towers.
For a concrete slab to be impacted by hydrostatic pressure, it must be below the water table on the site or intrude into a natural water pathway.
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
7,094
25
48
#19
For a concrete slab to be impacted by hydrostatic pressure, it must be below the water table on the site or intrude into a natural water pathway.
according to my contractor (I'm no expert in any way), a measurement was done to the ground under my room prior to the concrete pour for my room, and it was determined that the moisture content and hydrostatic pressure (the term he used) was such that I could use glue down wood flooring to the concrete since I was also using HVAC and my room would have a constant controlled temperature range. also, to your point, the grade was above the water table and not on fill (the term used was that I'm on glacial till).....and no springs or other factors.

the measurement was done at multiple times in the winter and early spring time, maximum moisture times here in the mountains of Western Washington state. some types of soil have higher moisture content than other types.

my issue was that I wanted a wood floor (over concrete) under my speakers, but mostly wood floor requires some sort of air gap when installed over concrete to allow for expansion and contraction as the temperature and moisture changes in the ground. since my acoustic designer spec'd wood, and I anticipated having quite heavy speakers (my current speakers are -4- 700+ pound towers) and I did not want the floor to flex and have to fight that issue.
 
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#20
according to my contractor (I'm no expert in any way), a measurement was done to the ground under my room prior to the concrete pour for my room, and it was determined that the moisture content and hydrostatic pressure (the term he used) was such that I could use glue down wood flooring to the concrete since I was also using HVAC and my room would have a constant controlled temperature range. also, to your point, the grade was above the water table and not on fill (the term used was that I'm on glacial till).....and no springs or other factors.

the measurement was done at multiple times in the winter and early spring time, maximum moisture times here in the mountains of Western Washington state. some types of soil have higher moisture content than other types.

my issue was that I wanted a wood floor (over concrete) under my speakers, but mostly wood floor requires some sort of air gap when installed over concrete to allow for expansion and contraction as the temperature and moisture changes in the ground. since my acoustic designer spec'd wood, and I anticipated having quite heavy speakers (my current speakers are -4- 700+ pound towers) and I did not want the floor to flex and have to fight that issue.

What I have found, (building contractor) homes built below the water grade for the area do have a chance of water intrusion unless measures are taken to improve the grade. In Fla if your below the water table in a coastal area you had better have flood insurance. We do not build any new homes unless they are above the water table to ensure hydrostatic pressure is controlled and that means adding trucks of fill dirt and compacted to be above the flood table.

Hydrostatic pressure, by nature, does not occur in slabs above grade. It does not even occur in every slab below the soil line. For a concrete slab to be impacted by hydrostatic pressure, it must be below the water table on the site or intrude into a natural water pathway. Water, underground as well as above, moves downhill under the pull of gravity, and so sites cut into a hillside stand a greater risk of having the “hillside side” be affected by hydrostatic pressure if adequate steps to redirect the water (and the subsequent pressure that might build up as it accumulates) are not taken. Poor drainage may cause water to collect against a concrete foundation, but generally will not build up the volume to cause problems attributable to hydrostatic pressure. Improperly dried concrete, sprinklers, plumbing, city mains and other water supply lines may be a source of moisture if they break or a joint fails can cause a Hydrostatic pressure point under the slab.
 

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