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If I try it on my pianos, I get a lot of noise out of the C, with a definite bias towards the C pitch. I would think that there is enough coupling of energy through the bridge to excite the string, and most of it will be in C. It is not as strong as if I hold the C and play the C an octave above it, however.

Perhaps rather than saying "this shouldn't happen" it would be better to think of possible reasons why in fact .... it does!

Sympathetic vibrations and harmonics are without doubt part of the overall character of pianos, but adjacent notes being influenced might well be the result of closeness of frequency. When there is relatively little difference between adjacent notes, it may be more a case of a phase shift causing an interference beat that excites the non-played note.

This would account for the lack of like similar behaviour if trying to emulate the same scenario using octaves above and below .... their frequencies being way to far from the resonant frequency of the un-played note.

I can see that kawaii (and other excellent manufacturers) have most likely tried to be as close as possible to the real thing, but whereas an acoustic piano needs quite a powerful strike on an adjacent key to get this effect, digitals tend to have software designed to trigger certain results, on a "if that .... then this" type of senario.

If I had anything to do with improving digital piano software design, I would be looking at linking the velocity side of the design to match more closely the effect on adjacent notes .... more so in the bass and tenor sections where frequencies are closer.

Lets not get into a running battle though ..... I'm just thinking out loud

Emmery (and Johnkie and others). If one starts to do physics, one should get the physics right. In terms of physics every string that loses some of its energy to its surroundings, by whatever mechanisms, is what physicists call a "damped" oscillator. (That has nothing to do with the dampers in a piano.) And the physics tells you that any damped oscillator does not only react to (= acquires energy from) harmonic vibrations that reach it, but to frequencies very close to its fundamental mode as well. (*In addition*, there is the response of the string to the noises made by the hammer when hitting strings closeby, and other complex effects, depending on the construction and the circumstances. That response leads to an excitement of certain overtones in a given string, just as BDB reports.)

But whatever physics tells you, you have hands to play and ears to listen to your piano(s).

I will leave the matter here, have fun with the thread.

Has it occured to you that C# or B have no harmonic/musical connection to C. Nor do we as tuners use two attached semitones as a tuning interval. Also, manufacturers strive to hit the string with the hammer near the node point of an unwanted but naturally occuring partial (eg. C3- A#5 or D6). What logic would there be to have the sound of C3's fundamental in the mix of C#3's sound or vice versa? I can't imagine a software engineer deliberately trying to do this.

I just checked my C3 note with MatLab spectrum analyser and it's fundamental does not show after trying to excite it with B2 and C#3. My ETD RCT is not picking up on it either with full gain and the mike cranked up. Most importantly, I'm not hearing it either.

I would however love to hear any accoustics/physics/scientific explanation or formula that explains how non coincidental frequencies bring out sympathetic vibration or resonance in an object or string in a supportive manner. The imput of the vibration would have to be equal to the natural resonance of the object to build sound...anything other than this would cancel it by vibrating out of frequency with the resonance pattern.

I still want to know, why in the heck anyone would want to do this in the first place? What purpose does it serve?

One more experiment pretty much confirms what I said. Playing a note adjacent to a note that is held silently will excite the silent note through energy transferred mechanically. The proof of this is to hold a note at the break, and try the adjacent note on the same bridge and the adjacent note on the other bridge. The one on the same bridge will make the note held silently sound louder than the one on the other bridge, which has a more distant mechanical connection.

You could describe it this way: when you first strike this adjacent key, there is a sudden pressure wave that is somewhat close to the frequency of the adjacent note. If you hit this note VERY hard and staccato, you can induce a very small amount of movement in an adjacent string. It's not the same thing as sympathetic resonance however. Achieving a note in an adjacent string requires you to make the excitation note very short, because if it is allowed to keep vibrating for a time, it will interfere destructively with the adjacent note. This effect is reliant on the non-struck string not being able to really "see" the frequency of the string that is exciting it. If you try it, you can hold down a B and belt a C really hard and short, you will hear a faint B coming through. This is caused by this pressure high wave which can induce movement in the string. If you do the same thing, but hold the C for a couple of seconds, the B will pretty much disappear. That's because the frequencies are unable to couple, instead they cancel. There is nothing to sustain the B. Real sympathetic resonance involves genuine coupling of frequencies and it will continue for as long as both notes are free to ring.

I would consider it a waste of time to bother trying to incorporate this effect in a digital piano. It also comes through far too loud in the clips of the Kawai. This is a problematic emulation of sympathetic resonance. Of course, you can turn the resonance down on a DP, but that punishes the resonances that should be relatively strong - octaves and fifths.

Duplicate post - Piano World was reporting database error.

Bogs, I'm wondering - did you try turning off the sympathetic resonance in the digital? I do not work with digital pianos much, but I have used some of our digital models and this is an adjustable parameter. The functions in the digitals are made to simulate the sounds created in acoustic pianos as closely as possible.

Now Emmery wrote: <When you write to a company inquiring about their product, there is no guarantee that a qualified person replies with a decent answer. In fact, most companies have a series of defenses you need to wade through to actually get a decent answer from the proper person who knows what they are talking about.

The first line of these defenses are people (often secrataries)known as deflectors. They typically know nothing about the product and throw "canned" form letters . . . . . . etc.>

Emmery, I don't know where this comes from, but it is a load of nonsense, to put it politely. It amazes me to read these kind of statements made in forums stating vividly imagined fiction in an emphatic and authoritative manner.

First of all, there are no "secretaries" at Kawai. All technical support calls for digitals go directly either to an electronics technician who knows the products inside and out (Juan), or to the person who is responsible for developing the sounds and functionality of the instruments, Alan. There is also a parts person to take parts orders. All technical support calls for pianos go directly to a piano technician (there are 3 at Kawai America including me), or to a parts specialist. If a call or e-mail goes to the wrong person, everyone in the company knows to forward it directly to the correct person in service, and no one would do anything resembling what you wrote.

So Emmery, back off a little and realize that piano companies are staffed by people just like you. Kawai and other piano makers are not huge corporations with layers of staffing intent on deflecting issues. All of us have the attitude that solving a problem is much better for everyone than letting it go unresolved.

Don, my posting on how many companies operate to handle questions/complaints was generic, even though it was within the topic of a Kawai related issue. Its just something people have to watch for these days. From your explanation, Kawai seems to handle this better than most companies. Try getting technical advice on a Young Chang/Kurzwiel DP and you will know what I mean by the term "deflection".

Still, I find it highly doubtful that a service tech, design/software engineer, and programmer are one in the same person or that any of these specific professions (Kawai or anyone else) requires full competancy/training/related qualifications, of the other two. It is still worthwhile to try and make sure one is talking to the right person, or confirm that the company is delegating questions/complaints to the right people. Eg. Programmers can verify if an engineering spec was properly executed in the software. Engineers can verify if the foundations of the specs are in line with what the product is supposed to do. Technicians in the field can replace circuit boards, diagnose problems ect..

The answer given to the OP by Kawai that the sound heard on playing those notes is "normal". This does not indicate if it was intended by design, or just a byproduct of other factors (flawed programming or an adjustable setting for eg.) Squeaky body parts on a 1970 Vega is pretty "normal" if you ask a mechanic or an owner of one. GM certainly didn't intended it to be by design.

On acoustic pianos numerous things are done to lessen or eliminate unwanted sounds or harmonics. Cloth is woven into parts of strings to dampen them, hammer strike point coincides with node locations of unwanted partial(s), scaling design tries to lessen inharmonicity, tone issues or uneven downbearing. I think its far fetched to believe a DP will try to incorporate into its design something which an accoustic piano manufacturer effectively went out of their way to eliminate. Certainly not to the degree that can be heard in the OP's sound sample. Besides, there are numerous other wanted things they are still trying to emulate off accoustic pianos and not being 100% succesful with.

Don is right. I've called Kawai, Yamaha, Steinway, Bosendorfer, Young Chang, Baldwin and many other companies lots of times over the years for various reasons. I have always gotten the right person from the start, have always gotten answers and good ones at that to any and all questions that I had to ask, particually at Kawai and Yamaha.

I always get my calls returned, emails answered in full and have been extremely happy with their vast knowledge which is way more than mine in many cases which I readily admit. That's one of the reasons we call them after all, with questions and problem solving if we do not have the answer along with other things that we encounter that we need help with or for warranty issues---the go ahead to fix it sign from them.

I have no complaints whatsoever about the technical department at Kawai and I've dealt with them A LOT over the years. They are great listeners that will add my input or suggestions toward solving any future problems that may exist if what I suggest helps....

Don in particular, has always been extremely helpful and gracious with his time with him with any and all questions or issues that I have brought up and, we have solved all of them between us.

I still wonder, why a person would do this to a piano or anything else in the first place? Again, what purpose does it serve?

Once again: Because it simply can't be avoided in an acoustic piano. Listen to your instruments.

And why would a DP manufacturer emulate this? Because he wants a realistic simulation of the acoustic piano. - Of course there are many acoustic effects around in a piano, and the choice of the ones to emulate is always debatable.

maurus, I can pick up the fundamental tone of that C note in the sound clip with my spectrum analyzer, with my ETD, and audibly with my ears. This is coming via my computer speaker. I can't pick up that same frequency on my 2 acoustic piano with any of the equipment, or my ears. Okay, so maybe some people pianos exibit this slightly more where they can. I doubt however that its as loud as the sound sample, or contains just the one frequency.

Also, introducing an additional frequency into a tone which is based on +/- the 12th root of 2 serves no harmonic/musical purpose. Additionally, piano performers are not taught to, nor does any musical score indicate to strike a key on the piano so slowely/softly to not sound it...there is no "Zero Forte". Its an impractical application because a played and held note can sustain up to 10-15 seconds on its own. Most importantly, the DP would display this same phenomenom if the sustain pedal was held down...because an acoustic piano would. Holding that C key down or applying the sustain are the same thing... a process that lifts off the damper.

I must have missed your reply the first time.

But, holding a note down, slowly letting it down, then playing surrounding notes around it, most certainly can be avoided. That part, is intentional and is what I'm wondering about. What for, how come? .

And yes, holding one note down, and playing others around it will elicit strange sounds from other places in the piano. So long as the damper is lifted, even your voice will come through more strongly on certain notes than on others.

Ah, perhaps I misunderstood your question, Jerry. Of course it is indeed rather improbable that someone silently presses a key and then plays around it. But in experimental music you never know - I've heard many interesting things. And, closer to the usual things: (1) Play a chord, say F major, hold it with one hand, and play some black keys in between - what gives? Or: (2) Use the sostenuto pedal.

A piano is a terribly complex instrument, and one should never say never. It does what it does.

PS. I really don't know what's up with Emmery's ears or instruments...

maurus, even the 30th partial off a string is present in a string's sound. Do we recognizably hear it? No. Do DP's emulate it, no. Do we use it in tuning intervals? No. If we eliminated it, would it matter? No.

The complex, wide spectrum energy from the hammers impulse can move via the bridge/soundboard over to another note to induce vibration in it...and not just the string beside it. Its just not very loud, nor is it supportive, because it does not share sympathetic resonance the way ghosting tones do with related string harmonics.

There are numerous sounds which are present on an accoustic piano which are not even related to strings. The bump sound of a key stick on the balance rail precedes the string sound by several thousandths of a second. This is more evident and easier to reproduce on a DP (same tone), yet to date, DP manufacturers haven't bothered to.

So why would they reproduce an un related, non harmonic, non sympathetic tone on only adjacent keys, and not have the sustain pedal do the same, or do it the same way on all keys. This minute sound would also be there from non adjacent keys also. Wave energy does not decrease with the inverse square law in solid objects like the bridge, as it does in air.

Although I cannot get this effect on my piano, or others when I thought of it, I happened to try it today on a 60s Rogers and got the effect at about the same level intensity as in the video irregardless of using staccato jabs or not - (Ando). So there you go: some do, some don't.

It's what I think too. But the question still remains why some do and some don't. We've heard possible explanations why they do:
1. mechanical energy is transferred to the adjacent string by the not-rigid (free to vibrate) parts of the piano
2. an undamped string is influenced by frequencies very close to its own ( first image on the right ) - although I have my doubts about his one, I'm waiting for a qualified person to comment

Now why are there pianos that don't exhibit this behavior? Both no.1 and no.2 easily apply to all pianos...

P.S: I wish everybody would cooperate and that this thread would not turn into 'I'm right, because I can hear it on my piano'/'You're wrong, because I can't hear it on mine'. This is the reason I posted this in the piano tuners section, because I though people here would deal with a lot of pianos, not just their home one [the Piano section] and thus not be biased.

I'm also not interested if this is wanted or not - good or bad, I would like to know why it's audible on some and not on others

I'd look for natural resonances in each piano, as suggested by the first para of your Wikipedia reference.

In physics, resonance is the tendency of a system to oscillate at a greater amplitude at some frequencies than at others. These are known as the system's resonant frequencies (or resonance frequencies). At these frequencies, even small periodic driving forces can produce large amplitude oscillations, because the system stores vibrational energy.

natural "resonances" occur also from dampened strings. on tall verticals damping is not very efficient (as it was on first old forte pianas)

But even when it is, I blieve that some reaction remain from the damped strings, that can participate to the tone of the played notes