How much difference does hardwood floors make in sound?

Whenever I play a piano at the carpeted piano store, it sounds relatively muffled compared to my piano, even with the top wide open. My piano seems very loud in my house that has hardwood floor and a 9 foot ceiling with no furniture anywhere near the piano.

Just curious what other players have observed about the effect of home acoustics (hardwood vs carpet) on the sound. Has anybody found an improvement in putting an area rug under the piano?

Yep, there is a difference. If its too loud, I would start with putting a carpet under the piano. One that reaches under all three legs.

But, trying to compare different pianos in different acoustic environments is nearly impossible. As a technician I tend to focus on the mechanical feel of the action and the quality of the sound. To hear how the instrument plays into the room, I have to call in a professional and stand back.

Hardwood floors make a big difference. The more hard surfaces in the room, the louder the piano will seem. Curtains, rugs, wall hangings, tapestries, etc, can help within limits.

What is under the wood floor?
If there is air space under there and not concrete, the wood will vibrate sympathetically and could enhance the tone.
Especially if you have brass, not rubber casters.

It will make a large difference in the sound. Louder and brighter usually.

The piano is going to sound the same no matter where it is played. What changes is energy mix of the reflected sounds that reach your ears. Since quite a lot of the energy that reaches your ears is reflected energy from the floors, walls and ceiling your perception of your piano’s tone characteristic is heavily influenced by the acoustic properties of the room in which the piano is played.

Floor carpeting and/or rugs placed under the piano will affect the amount of energy reflected by the floor. The amount of sound energy absorbed by carpeting depends on the nature of the carpet and the frequency of the sound energy. Most carpets absorb very little sound energy at frequencies below about ≈ 250 Hz (A-37, or the fourth A from the bottom, has a fundamental pitch of 220 Hz). Most of the sound energy below ≈ 250 Hz that reaches the floor immediately below the piano will be reflected back into the room. It is above this frequency that absorption into typical carpets becomes significant and less energy is reflected back into the room.

Pianos with even moderately hard hammers will produce quite a lot of energy above 250 Hz. Without an absorptive carpet below the piano, much of this energy will be reflected back into the room and, ultimately, to your ears. Even a piano that would otherwise sound warm and mellow can sound bright and hard in a hard room; that is, a room with little sound absorbing material in it.

Putting a carpet or rug beneath the piano will absorb some of the sound energy above roughly 250 Hz which will make the piano sound a little warmer and not quite so loud. (Don’t worry; the effect is gradual so you won’t notice an immediate cutoff just above A-37.)

The general rules are:
— Rugs made of natural fibers such as wool are more energy absorbent than are otherwise identical rugs made of synthetic materials.
— Thick rugs are more energy absorbent than are thin rugs.
— Large rugs, by virtue of their larger surface area, will absorb more energy than will small rugs.

If placing a carpet or rug immediately under the piano does not achieve the desired result you might also try hanging a relatively large decorative rug on the wall opposite the open lid of the piano. Placing the rug about an inch or so away from the wall will increase the amount of energy absorbed by the rug. (The same, or better, results can be achieved through the use of specialty sound panels. But they won’t look as nice.)

Somewhere in there you should also have a chat with your technician about hammer voicing.

ddf

I have a 9 Ft. grand on a floor that's hard laminate over slab on grade. There are window curtains and leather couches, but other than that, the rest of the surfaces are drywall. Nobody's had a problem with it being too loud.

As for quality, it always sounds better to me when I'm anywhere other than sitting on the bench playing.... Though I think that's not entirely an acoustic issue. ;-)

What Del said.

Large scale instruments seem to have better sound starting from approximately twenty feet away.

If that is the case then the piano is not properly scaled for its environment.

Large pianos typically are scaled for large spaces. That is, their stringing scales tend toward relatively high-tensions and their hammers tend to be massive and dense. When these instruments are placed in small rooms they can overpower the room.

The solution, of course, is to design pianos specifically for smaller environments. Tone down the scaling, lighten up the hammers, etc.

Selling these pianos would, of course, require a fair amount of knowledge and sophistication on the part of the dealer. He/she would have to be comfortable getting away from the notion that only power, power and more power is the hallmark of a good piano.

ddf

As an acoustician by trade, it always bemuses me to read threads like this...

Del is mostly correct. Although, that ~250Hz rule of thumb is very approximate. The sound-absorbing properties of carpets/rugs vary quite a lot. Some can absorb well down to 125 Hz, other floor coverings don't start to display good sound absorption until 500Hz. So I agree to an extent. It's 250Hz plus or minus and octave.

(BTW: Paper towels and sponges are "absorbent". When talking about sound, us acousto-weenies like to use the word "absorptive". And don't get me started with "dampening" vibrations! Nails on a chalkboard!)

J.S. doesn't tell us how large the room is volumetrically that contains his 9ft. concert grand. Makes all the difference in the world. Likewise the volume of space in the typical piano dealership is likely to be much larger than one's living room. Apples and oranges acoustically - both for volume and room finish treatments.

I also appreciate Del's comment about scaling the piano for the environment in which is going to live. The wrong piano can easily overpower a room and its acoustics.

Here's a photo of a room I just finished for a customer. I was a bit worried that the piano would overpower the room. As it turns out, it came quite nicely. I have to admit, clients like this don't come along every day!
Features:
Hamburg D
Elliptical room in plan
14ft+ ceilings
3/4" thick sound-absorbing panels on the walls (yellow velour areas)
custom carpet
custom tuned Helmholtz Resonator bass traps (63Hz and 125HZ) behind the brown velour curtain - to take up where the absorption of the carpet and wall panels drop off. (See? Helmholtz was good for something!)

https://picasaweb.google.com/lh/photo/eBgLR8rmpPekXanolSaKei8wpnug0a_ZaLhxCkTeYmY?feat=directlink

Chris S.

Indeed, I didn't because it's so complicated. The main part of the room is 18 ft. by 21.5 ft. with a ceiling that slopes from 16 ft. down to 9 ft. There's a low ceiling (8 ft.) dining area completely open from the high wall, 10 x 12.5 ft. There are also a stairwell and a hallway to an open family room off the side wall.

In the house, the 9 ft. doesn't seem any louder than the 6-4 that I had before. But it wasn't until I got it that the neighbor across the street commented on my playing. I know, that defies the inverse square law....

Seriously, though, when these big pianos get too long in the tooth for a concert venue (mine's from 1929), they can be a real bargain for the amateur who has room for one.

Interesting input !

is mass necessary to lower the absorbtive frequencies (I mean no matter what thre shape of the material , i.e. acoutical foams, if the mass is not enough, the frequency absorbtive (!) range is above "250 Hz"

Do you know if a room can be tested for its own resonant frequencies with a single computer producing white (or pink ?) noise, and recording the noise at the same time with a (good !) mike ?

Just to find the peaks ... I have seen once a software allowing that, but i dont recall where ...

Thank you for your input

PS also .. did you separe the casters from the floor ? I noticed that some floors can be OK (even wooden floors) and wondered to what point grand pianos can be sesigned for some floor transmission (raising the lower frequencies by solid transmission)
I often install rubber or decoupling goodies under the casters on wooden floors, but on any stage the floor participate to the tone (not on US university stages as you use dollies/trolleys, the name escapes me, unless ome wooden blovs are used to restitute some solid transmission the vibrations may be reflected within the instrument and I wonder up to what level it is good for tone...

BTW I can recognize with my eyes closed, if the front casters are oriented front or rear ! (if I know this is the test conducted)

Wow, what a place for a 9 ft grand!

Too bad the architect of the Dayton, Ohio Riverscape Pavilion didn't consult with you before they built that acoustic atrocity. The canopy makes it the best possible example of how *not* to build a performance space. When a crowd is settling in to their seats, the noise of their reflected chatter is deafening. Performers can't hear themselves, and the audience hears only a blur.

But it is just a tent, something temporary, that can be dismounted anytime.

I hate outdoors tuning for the lack of sound return they provide. here the canopy may send a lot of noise and mixed frequencies .. horrible place for music indeed (at last if it rain you are not wetted)

The trick to tuning outdoors is to get the movers to leave some blankets, and then drape them over the piano and you while you tune.

ideal if the weather is bad you can also use the blankets for yourself, they rub a little but better than nothing !

I started doing this when it started raining when I was tuning. I found that it blocked the ambient noise so well that I ask for the blankets whenever I can.

Unfortunately it's not just a tent. It's a $2+ million pavilion with a permanent roof made of flexible material suspended from poles. Evidently sound reflected from the outside of a quasi-hyperbolic surface is just as problematic as that reflected from the inside.

No. You're confusing two principles. In general, increased mass is used as a way to BLOCK sound from going from one space to the next through a wall or floor. Blocking sound is difficult at low frequencies, and requires special techniques which may include increasing the mass of the partition separating the two spaces. Sound is ABSORBED by thick, porous materials, generally with very little mass. Absorbing low-frequency sound is also difficult, and requires its own set of special techniques (bass traps, membrane absorbers, etc.).



Now you're talking about room modes, which is entirely different than the previous two principles. Room modes occur when a wavelength of a particular frequency of sound corresponds to the physical dimensions of the room in question. They most often occur between parallel surfaces (there are three pairs usually in any given rectangular parallelpiped space), and can occur at integer mutiples of the fundamental frequency. The resulting audible effect one hears from room modes are hot spots and dead spots in particular locations at specific pitches. One can try and reshape the surfaces to avoid the parallelisms, make the surfaces sound-absorbing instead of sound reflecting, change the surfaces to sound-scattering, or just tolerate it. Steinway's selection room at the New York factory has one wall that's canted out of perpendicular, I presume to avoid the room modes between the parallel walls. Again, as an acoustician, I'm bemused because the other pair of walls is still parallel and the floor is parallel to the ceiling.

There are room mode calculators on the internet. They generally identify the room modes for rectangular parallelpiped spaces. These are the tools many recording studio designers like to use, but they don't have much practical application to the real-world living rooms we work in. One can also go to a built space and measure the room modes, but you wouldn't use noise for that.

I once had a client who was really disturbed by the room modes he heard in his living room. When I told him what was needed to correct the problem, he quickly decided he'd learn to live with the room modes. He moved the position of the piano to get his head out of the acoustical hot spot he was hearing, and then promptly found another hot spot at another pitch.


Again, I'm bemused at caster cups being sold as some kind of vibration isolation for pianos. Some of the hard plastic or wood cups I see provide no vibration isolation whatsoever - none (except maybe the psychosomatic acoustical relief they may provide which seems to be directly proportional to their cost). The softer rubber cups would only be effective at high frequencies. Most of the ones I've seen aren't calibrated to the weight of a piano and don't provide the appropriate deflection to even perform well at that. The piano overloads the rubber such that it's essentially a rigid block. The way to vibration isolate a piano is to put it on a raised platform supported on SPRINGS. Only springs have the deflection necessary to isolate low frequencies. How likely is it that one could get a piano owner to build a platform for a vibration isolation problem? Not likely.

With regard to resonant coupling of pianos to stage floors, and whether that affects tone: It depends on whether the piano's on a dolly or not, rubber wheels or nylon wheels, and whether or not the floor is constructed of soft hardwoord, (or hard softwood), or too thick, or too thin, how far apart the joist spacing is, finished, or unfinished, the weight of the pianist, and the type of nails used to secure the floor, or whether Beethoven himself might have once walked across it....I've heard it all. Good luck scientifically determining the factors which affect tone. Tell me what you think you hear. I'll probably just smile and nod knowingly.

Now! Piano techicians. Go! And use your newfound acoustical knowledge for good!

Chris S.

Andy,

There are too many pavilions to count with this problem - Bank of America pavilion in Boston...Caramoor in New York....
The Aspen music tent is one example of how the tent was done well.

They do make a sound-absorbing inner liner for these tension-membrane roofs. They double the weight, causing a structural issue. And they double the cost. And the roof has to be replaced every 10-15 years.

See why they overlook any acoustical deficiencies?

Chris S.

I was really disappointed in the first music event I attended at this lamentable pavilion. I can't imagine the architect ever consulted an acoustic engineer or acoustician (I'm curious: what's the difference?), as the pavilion was intended for multiple purposes including staging performances. I contacted the director of the Dayton Cityfolk Festival to suggest not using the pavilion at future events, but he pointed out it would cost $10,000 to rent an appropriate tent as an alternative. I've never been in a worse acoustical space!

Maybe the architect's design included the inner liner but the park district rejected that as too costly. Whatever happened, it's really a shame -- people travel from far away to perform in that space, and many people come to try to hear them.

Thanks so much for your clearings ..
My test for rubber (I use pure latex or specific goodies as Piattino http://www.piattino.de/ (the last one designed for some decoupling, based on the rubber but also on the air enclosed)
I just stand near the bass side of the piano, without shoes, and feel the vibes when playing the bass notes, thru my feet.

After the casters or the latex is on, I feel them no more and the basses are less unclear.
I generally propose that for muddy basses but mostly for the neighbours (I also use designed rubbers as STABREN, with specific frequencies isolation ragne in regard of the weight they are subjected to : http://www.gouillardon-gaudry.com/fr/vibratoire/stabrenmesure.pdf

(they can be used up to 10 tons so differnt models exist)


A crude test I did once with friends 2 floors lower in a haouse: we listened to the tall vertical before installing the Stabren (200 Kg/4)

Wooden floor and resonant house ; after installation, the piano sound was mufled as if someone used the mufler.

Indeed a basic black or grey "latex" as can be find in usual stores to install under the washing machine are not effective for long, as the rubber is mixed with some other components and it compress soon.

Pure rubber is way better indeed but I only know one place in Paris where I can find those strange yellow squares of latex; i install the casters (they are in brass generally) and the weigh of the piano make a space in them, but yes the piano looks like if it is on springs !

Greetings

Basically I thought a customer could make a few bass traps to fight the static spots in his room (parallel, flat walls/ceiling, you know that ...

So a computation would be better than real measurements (I have seen the sound engineers testing a space with a spectrum analyser, I seem to recall they used white or pink noise ore something similar, to see the peaks of the romm under the amplification used.

I certainly dont want to make YOUR job, for sure , but we are faced dayly with acoustical problems due to the rooms where the pianos are

Best regards

The efficiency of the "Stabren" is really good (for the neighbors!) However the piano moves as if it is on a boat, so I stopped using that, most probably I only have to use a harder version of the product..

"The piano overloads the rubber such that it's essentially a rigid block. The way to vibration isolate a piano is to put it on a raised platform supported on SPRINGS. Only springs have the deflection necessary to isolate low frequencies. How likely is it that one could get a piano owner to build a platform for a vibration isolation problem? Not likely"

So the springy behaviour of the instrument seem to be a proof of the efficiency of the system (I understand it may relate to the amplitude of the bass notes) ..

Isaac,

Rubber - neoprene - latex - air cushioned insides - super secret squooshy stuff .... Remember, all that matters is the weight of each piano wheel and the corresponding static deflection of the isolator. If you're using a thin elastomeric isolator of any kind, you're going to get a relatively small static deflection. Small static deflections only isolate certain higher sound frequencies. In your experiment with the Stabren, what you did was you filtered out the high frequencies of the structural vibration path, but low frequencies were still allowed to transmit through resulting in the muffled effect you cited.

Yes, it was a noticeable CHANGE (different spectrum) of transmitted sound, but was it a significant REDUCTION (lower decibel value) in transmitted sound?

In order to structurally isolate the low frequencies and thereby achieve a reduction in transmitted sound, you will need to achieve 25mm - 50 mm of static deflection from the isolators. (That's why I said the most effective way to vibration isolate a piano is to put the whole thing up on a it's own isolated platform. Piano + pianist + bench ON SPRINGS).

You mentioned you are going to try more rigid(!) eleastomeric isolators to avoid the piano feeling like it's on a boat. If the piano moves as if it is on a boat, then the vibration isolation is working! I realize that situation is not stable, and therefore, it's not safe, but you can experiment all you like with elastomers, but it's never going to provide a miracle improvement for your customers. That's what I was getting at.

So please understand what's happening when you recommend elastomeric isolators for pianos, understand the limitations, and inform your customers appropriately. OK?

If you want a room mode calculator for future reference, one is located here. There are many out on the internet. They all do the same thing: They tell you what frequencies are going to be a problem, but tell you nothing about how to fix it. Useful... to a point...
http://www.marktaw.com/recording/Acoustics/RoomModeStandingWaveCalcu.html

Your friends with the laptop and the the micphones may have been using and MLS signal to analyze the room response and find room modes. It sounds like noise, but it's not.
http://en.wikipedia.org/wiki/Maximum_length_sequence

If you're having acoustical issues daily, find and build a relationship with a good acoustician. It might take some of the guesswork out of this. There are plenty in France.

And when was the last time you had your feet calibrated as a measuring device?

Yours truly,
Correcting the acoustical misinformation out there one post at a time,
Chris S.

Your posts are very informative Mr. Storch!!

I have a concert grand piano in a room about 25'x20' with only an 8' ceiling. When I first got this piano I had wall to wall carpets and a deep sofa, some other chairs and light curtains. I usually played with the top fully opened. No problem for me. Then I installed oak floors. I couldn't play the piano in the room at all. So I added a rug under the full length of the piano one under the bench and a large one in the middle of the room. The sound reflection problem was cured, the piano sounds clear with overtones better heard but now I only have the half top open when playing things like Rachmaninoff. On softer pieces I can short stick the lid.

That's getting into the range where the isolators might also offer the piano some protection from earthquake damage.... ;-)