> On Friday, May 2, 2003, at 12:48 PM, Phillip Ford wrote: >> At 11:48 PM 5/1/03 , you wrote: >> I'm not an engineer and will have to defer to those who can comment on > this >> in a more informed way, but your reference to the key doesn't change >> my >> point. Movement of the key is being resisted by a variety of factors >> the >> would eliminate any significant effects of momentum in key travel, or >> so > it >> seems to me. >> >> David Love >> davidlovepianos@earthlink.net > > As I see it this will be one of the problems that Stephen Birkett (or > any other contenders) faces in making a dynamic model of an action. > What input are you going to use? Does the player push down with > constant force? With constant velocity? With constant acceleration? > Does he push down with more force initially to break the static > friction and then back off to a lower force? Does he attempt to > rapidly accelerate the key in the first part of the movement and then > maintain a constant velocity for the rest of the > movement? Etc, etc. I'm sure you can imagine other various > scenarios. And it probably changes depending on whether the pianist > is playing legato or staccato, soft or loud, fast or slow, etc. It seems that, except when tempi are slow or note values are long, I don't have a lot of time to effect the precise hammer velocity I desire. So, during 'not slow' play I would say that I'm not making any corrections within the same keystroke. If I find I'm not getting the desired amplitude or tone then I'm adjusting for notes not yet played. I'm thinking that because of the relatively short amount of time available to play any given note it is far more likely that I'm combining finger velocity, hand/arm weight, wrist technique, etc to create enough force in more of a 'pregnant moment' (this is one case where we can be 'a little pregnant') to accelerate the hammer to the desired velocity by the time it hits the string. In this case the friction, action 'wind up', gravity, and hammer mass conspire to counteract that force, so my guess is that I'm sensing the response characteristics of 'this particular action' so that the hammer (whether accelerating or deaccelerating) will strike at the desired velocity. Something like fireworks - the propellant stops 'propelling' before the rocket reaches its apex. So, I'm firing with a particular force for a particular duration whose termination may not be the hammer strike in order to propel the hammer to strike the string at a desired velocity. In slower play I'm more likely to use greater mass of hand and/or arm weight to control hammer velocity. > This information is the input to a model, not the output from it. The > model isn't going to tell you how the pianist is pushing down the key. > If you tell the model how the pianist is pushing down the key it will > give you some idea of how the action is responding to the input. So > you first have to do a rather > elaborate study to determine in what manner pianists push down keys. Sure are a lot of variables, not the least of which is that performers aren't necessarily consistent or efficient in the way they play. ( A professor of mine used to say,' I can always tell you what I think the best fingering is, the most efficient way to practice, the most efficient way to play, but in the performance world it all boils down to 'CAN YOU DO IT?''. (If you can do it no one really cares how you got there) So what is the purpose of a dynamic action model? to study the action? to study pianists? both? Can we start by studying action dynamics first? We already know that pianists adapt to actions regardless of the design/performance? Actions do not adapt to pianists (at least not on the fly). We could assume that pianists (at least this one) desire the greatest efficiency and consistency ( even if after the fact they lament 'too light', ' too heavy') that can be had. We might presume that pianists would adapt (perhaps graciously, appreciatively) to an action that was made more efficient & consistent (and didn't increase impact trauma). Still dreaming. Best, Rich Olmsted > Did I hear someone say Ph.D. thesis? > > Phil F > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives >
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