A single musical tone is in reality composed of 10-18 tones that form the series of harmonics. The mass of tones is condensed into one sensation by our ear. The force (tone amount) of the overtones in relation to each other and to the key-note show unlimited variations. If the high overtones are relatively strong we will have the sensation of a sharp, hard tone. If the lower overtones are stronger we will have the sensation of a soft tone. Thus the tone colour depends solely on the number of the overtones and on the proportions of their intensity. If in two musical tones the number and proportions of the overtones are the same, their colour will also be felt as being the same. This is what I call the search for the control of the evenness and of the equality of dynamics and timbres.
An essential feature of the mechanism of the piano is the immediate rebounding of the hammer after having touched the string. If this were not true the vibration of the string would be impeded. Therefore the last part of the route of the hammer must be travelled entirely unhindered. This is known as “free travel”. The shorter the distance of free travel, the more the player will feel he is master of the motion of the hammer. However, at the moment of the striking of the string the hammer has to move entirely freely, independently of the key, in order to allow a free rebounding of the hammer.
As the hammer moves freely at the moment of striking the string, the only variable component of this motion is the velocity of the hammer.
The velocity of the hammer at the moment of striking depends solely upon the velocity of the key attained at the escapement level. Thus, if the pianist wants to carry through alterations in the velocity of the hammer (and thus in the tone), he has to change the velocity of the key.
The tone colour of the piano depends -apart from the construction of the piano (stringing, material and making of the sound-board, ecc.)- mainly on the type of the coating of the hammer and on the quality of the felt. The way the felt has been coated affect the length of time during which the hammer touches the string. An increase of the time of this contact will proportionally give prominence to the low overtones while a decrease will make the higher overtones dominate. A longer time of contact will be more favourable for the sounding of the lower overtones and thus softer tone colours will be obtained as a result. If the contact time is a short one the higher overtones will become strong, and the tone will be felt hard and sharp. To attain soft tone colours the piano manufacturers had to construct hammer heads permitting a maximum contact period of hammer and string. This was realized by providing the hammer with layers of different hardness: progressively softer layers are applied over the hard centre.
The number of overtones increases in direct proportion to the velocity of the hammer stroke. Alterations of the tone volume therefore bring about changes of the tone colour.
Different kind of noises are always produced simultaneously with the musical tone and they must be taken into consideration in the development of the sensation of tone colour. Noises can be caused be the collision of the wood of the key and the key-bed, by the collision of the hand and the key, and mainly by the vibrations of the hammer and the string at the moment of striking the string. Noises will spoil the tone quality because the less the noise-effect the more “carrying” and sonorous the tone will be.
The so-called escapement enables the hammer to fall back immediately after striking the string and enables the hammer to cover the last small part of its route completely free. The hammer cannot be brought to the strings by a uniform motion and therefore a swinging motion has to be applied in order to give the hammer the required energy. I consider pressing a constant application of force. If, instead of striking a key, we push it down by a slow, even motion, no sound will result. If , on the other hand, we press the key to the bottom after the stroke, we perform unnecessary work, and this will detrimentally affect other movements. “Pressing” will lead to such faults as pressing down the key to the bottom of the key-bed, and even keeping it there with a display of force. If the pianist depresses the key he fails to take into consideration the laws of the operation of the piano’s mechanism. Since the release of the hammer takes place near the middle of the downward course of the key, (at the escapement level), any further movement of the fingers is unnecessary. In order to cause the hammer to strike, it’s essential to execute an active swinging motion starting from one of the joints.
Our movements are carried out by antagonistic muscles which counterbalance each other. For example, in raising the forearm the greater part of the work is always done by the extensor but, depending on our will, the flexor carries out a counteracting movement of varying intensity, slowing down and controlling the movement. On all of our movements there is a minimum of this braking effect; in the case of a controlled movement it will increase and, parallel with the intensity of control, became gradually more noticeable.
What I call “Control” is the increasing of this braking effect of the muscular activity. Every swing-stroke should be controlled. This means the control of three parameters: mass, highness, velocity.
