Acoustic Memory

[Greg Newell]

Rob and list,
    This is an interesting theory. The first thing that comes to mind
about "training the board" is that you're assuming that the frequency
never changed over those few billions times the hammer comes in contact
with the string. Even with a very fast repetition we are still talking
about a long period of time and the piano is sure to go at least a
little out of tune. What will that do to your theory?

Greg

Robert Goodale wrote:

> Hello all,
>
> I was recently having a personal conversation with Eric
> Frankson from this list, (hello Erick), regarding the
> current thread on sound boards, new vs old and improvement
> with age.  During this chat something kind of odd occurred
> to me.  Perhaps this is a pretty big stretch but I suppose
> there could be some merit that warrants discussion.  The
> concept is what might be appropriately called "Acoustic
> Memory".
>
> Wood has some known properties regarding the natural places
> it wants to be.  For example a piece of low-grade and poorly
> cured lumber will warp and curl with the grain from it's
> present position to a more relaxed position in favor of it's
> new environment.  In a somewhat similar approach, a quarter
> sawn and properly cured piece of wood wants to remain
> perfectly straight.  If it is forced into a bend under
> pressure it will return to it's previous position once the
> pressure is removed.  However, if such a piece of wood is
> forced into a curve and then made to stay there for an
> extended period of time, (perhaps a few months or even
> years), when the tension is released the wood will retain
> it's unnatural curve because it has been trained to be in
> that position over time.  It has "memorized" that position
> and it wants to stay there.
>
> What if we could apply this principal to the acoustic
> properties of a sound board?  I'm not referring to board
> crown here, rather I'm thinking of the "memorization" of
> vibrative distribution within the board.  Let's look at it
> this way.  Any particular note, (say A-440 for example), is
> generated from a specific set of three strings, travels to a
> specific set of six bridge pins, and the vibrative energy is
> transferred into the board via specific conduits, (i.e.
> physical corresponding wood fibers).  Once in the board the
> vibrative energy originating from that particular spot is
> distributed in specific calculated directions.  No other
> note in the scale follows the same path, only these
> particular strings produce this frequency, enter the board
> at this exact spot, and travel through the board in the same
> way.
>
> what I am visualizing here is something like a vibration
> table, something that you might find in a physics lab.  With
> the table vibrating at a specific frequency, sand poured on
> the surface of the table will dance around until it develops
> a particular pattern on the surface which it then retains.
> The pattern corresponds to not only the frequency that the
> table is tuned to, but also by the various sizes of the
> grains of sand.  If the frequency is changed the sand will
> dance into a new pattern.  If the sand is replaced by
> another material having a different density it too will have
> it's own distinctive pattern.
>
> So going back to the sound board, it is conceivable that a
> given particular note is projected into the sound board and
> then distributed into the board the exact same way each time
> that note is played.  Other notes will have their own unique
> patterns as well.  When different notes are played together
> such as in chords the patterns blend to create a variety of
> tonal colors.  The mathematics behind this must be
> infinitely complex.  The concept does however help
> illustrate how scale design, bridge placement, and sound
> board size and shape can have such a critical and dramatic
> role in a piano's tonal quality.
>
> Where I'm going now may be a bit of a stretch but it may
> have some merit.  Just like a piece of wood memorizes it's
> position after being forced into a bend for an extended
> period of time, could the physical properties of a sound
> board at the cellular level develop "acoustical memory"?  In
> other words, after A-4 has been played a few billion times
> could the wood fibers responsible for distributing that
> particular note begin to memorize that frequency?  It seems
> possible that there may be some wood memory here just like
> wood being trained to assume a bend.  If this is true then
> this could help explain why some pianos seem to sound better
> with age.
>
> There are of course many other factors at play here such as
> changes in crown and down bearing.  I'm not even sure if it
> is possible to test this theory let alone prove it.  If this
> were fact however then perhaps a technology could one day be
> developed to "pre-trian" a board during manufacturing to
> sweeten it's acoustical properties.  I'm not even sure how
> you would go about doing this.  All of this is purely
> techno-babble and may amount to absolutely nothing but it
> seemed like there might be a valid concept.  Sorry if I have
> tortured your brain cells.
>
> Rob Goodale, RPT
> Las Vegas, NV

--
Greg Newell
Greg's Piano Forté
12970 Harlon Ave.
Lakewood, Ohio 44107
216-226-3791
mailto:gnewell@ameritech.net