An intelligent player should
know the fundamental physics of his/her instrument.
Here is a factual presentation of how the sound is produced inside the piano:
(1) In order to produce sound, we need energy to deliver to a metal string
so that the string can vibrate. Inside the piano, each string is tuned to a
primary pitch which is the fundamental tone for that string. But when the
string vibrates along its entire length, it also vibrates in segments,
producing a series of overtones or harmonics.
(2) Depressing a key in the keyboard causes a series of actions inside the
piano that eventually throw the felt covered hammer towards the string, thus
causes the string to vibrate producing sound (primary pitch and overtones) .
After the sound is produced, the hammer rebounds immediately and a damper
will move forward to shut down the vibration if we don't hold it off.
(3) Everyone from high school knows that there are two
kind of energies: potential energy and kinetic energy. The
main source of energy that the hammer carries is the kinetic energy when it
is being thrown or activated. (the potential energy can be ignored here
because the hammer can not move vertically anyway.)
The physics formula for kinetic energy is:
where: KE - Kinetic Energy
m - mass (in this case, the mass of the activated hammer)
v - velocity (in this case, the speed of the activated
(If you do not have a scientific background, don't
be discouraged. Just get the result and move on. For those with a
scientific background, you are welcome to discuss this matter with me.)
(4) Since the m (the mass of the activated hammer)
is a constant here, we are not interested. We are only interest in the v,
which is the speed of the hammer hitting the string. Notice that the kinetic energy
changes with the square of the v. That means, a
slight change in the v will result in a larger change in the volume
of the sound thus the tone quality. For example, 10% change in the v
will cause approximately 20% change in the volume (1.1*1.1= 1.21), 40%
change in the v will cause the volume almost double! (1.4*1.4= 1.96)
It is good to know when you play the piano.
(5) Furthermore, the sound is produced before the key
reaches the key bed. You can experiment it on the piano by depressing the
key slowly. You will hear the sound before the key reach the key bed.. Once
the sound is produced, the hammer rebounds immediately and the sound
diminishes gradually. Nothing in the earth can change the piano sound after
it is produced. (manipulate the damper can affect the tone quality, but it
is beyond the scope of this article*). It is not like the violin in which
the player can use the bow to improve the tone or the singer can use their
breath to change the volume. Pressing against the key bed after the sound is
produced is most stupid, it is a bad habit, a waste of energy and it
causes fatigue. We need to relax our muscle immediately after the sound is
(6) There are only two cases that we need to hold the key
down after the sound is produced. (but please be relaxed, holding the key down
does not require any muscular effort, just use the weight of your arm.)
- In the case that we need to hold the key down to keep the damper
off the string, thus prolong the sound.( but it diminish gradually
- In the case that we need to use the key bed as the floor for
another finger to reach the next key.
The facts presented here may puzzle some piano players,
because traditional thinking is that the more force you use, the bigger the
sound. Some piano players habitually press the key after the sound is produced.
Some used to forcefully strike the key causing too big the v, thus
generates unwanted overtone resulting in unpleasant, harsh sound.
Based on the above factual analysis of the actions of
the piano, we come to the following conclusions:
1) Nothing can change the piano sound after
it is produced. Pressing against the key bed after the sound is
produced is a waste of energy and causes fatigue. We should
relax our muscle immediately.
2) The volume of the sound produced is
proportional to the square of the v, the speed that the
hammer hitting the string. Too big the v will result in
harsh sound which we should always avoid.