hammer velocity

[Bill Ballard]

At 8:59 AM +0200 4/26/03, Richard Brekne wrote:
>The only aspect of the travel of the hammer the pianist can
>>  control is its velocity.  There might be an argument about this in
>>  physics because of the difference between velocity and
>>  acceleration.
>
>I am sure you are right here.... (about the argument part) I have read
>through 8 or 9 articles by those who have done the only readily
>available real science on the subject matter and they dont draw any hard
>conclusions.

The letter "x" is one element in the alphabet, the same way A4 is one 
note on the keyboard, one sound in the air. String the letters of the 
alphabet together (including spaces and punctuation marks) following 
the rules of language (yours, mine or theirs), and you'll get an 
expression of human thought. String notes (and combination of notes!) 
together following the rules of a given musical tradition, and again 
you'll get an expression of human thought. (Yes, the products of the 
mind are far more interesting when they show the evidence of a heart.)

Play a single note with a human finger followed by one from a dead 
weight (chosen to match the force of the first, human key stroke), 
and you won't hear any difference. Give the pianist the sheet music 
of a piece cut into a player piano roll, and compared that to the 
performance by the player (not reproducer) piano, and you wouldn't be 
human if you didn't hear the difference. Granted, a modern Yamaha 
Disklavier can come closer to reproducing the nuances of human 
performance than most humans can detect. But this digital marvel 
still can't performance with nuances of its own.

So, yes, as far as activating a note on the piano, the significant 
factors (the hammer's mass, its velocity at impact, the texture of 
its crown and the friction at the shank center) are all outside the 
control of the pianist. Making music, as with poetry, is another 
matter.

Speaking of hammer velocities, these ought to be available from any 
of the digital player/recorders with optical motion sensors. 
(Granted, only the R&D people would have access to them.)

As far as hammer velocity, how you use it depends on what you want to 
measure with it. When impelled by the action, the hammer is the 
receiver of the force. Measuring the net force given to it by the 
pianist would involve its mass and the acceleration to its speed at 
the instant when it was disconnected from the pianist's force 
(immediately on completion of LO). When the hammer slams into the 
string, it's the giver of the force. Measuring the force given to the 
string by the hammer would involve again, the hammer's mass and the 
deceleration of its speed at the point of impact to zero (with the 
string at maximum displacement). Somewhere in there is the fact that 
the hammer is hitting a spring (not a brick wall) and that part of 
the energy given by the hammer is returned to it by the string 
throwing the hammer out of the way after it reaches maximum 
displacement. The hammer felt is its own spring as well.

Slowing down is acceleration also, just a negative one.

Bill Ballard RPT
NH Chapter, P.T.G.

"Talking about music is like dancing about architecture"
     ...........Steve Martin
+++++++++++++++++++++