Piano secrets I

This title is a bit misleading. I do not intend to share the ultimate secret to piano playing because such a secret does not exist. However, I do know some minor facts regarding the physical act of playing the piano that may be of potential interest to some of you.

Touch, strength, sound volume and quality

You may wonder how some famous pianists achieve a wonderful clean, majestic sound quality even in loud volumes, without a trace of harshness. This is very mysterious at first because it seems that the only variable that dominates the impact of the hammer on the string is the speed with which a key is pressed. How can the quality of the sound depend on a single variable that, obviously, mostly influences sound volume? The answer lies in the fact that the keyboard is not a "mathematical model" but a real solid mechanical system and a rapid acceleration can induce a temporary elastic deformation of the lever that bears the hammer. Therefore the hammer-lever-axis system carries energy in two ways, as kinetic energy of the hammer movement and as dynamic energy of lever deformation. The dynamic energy of the system induces an oscillation of the hammer relative to the axis (think of a ruler or a long strip of metal being bent and then suddenly released). Now, the tricky part is that this oscillation is not related to the native frequency of the string and upon impact causes the string to oscillate in its native frequency (clean sound) plus the oscillation frequency of the hammer mechanism (not harmonic, "dirty" sound).

In practical terms this means that if the key is accelerated rapidly then the hammer-lever system is deformed and the sound is "aggressive" and "hard" because of the extra transient non-native frequencies of the string upon impact. If the key is accelerated smoothly, but with a similar final velocity, the sound is equally loud but smoother. This is very intuitive, but hard to achieve in practice: if you hit a key with a rigid hand you force the hammer to accelerate suddenly. A hand in tension causes aggressive sound. A relaxed hand causes smooth sound. Doing this requires tremendous amounts of practice because great playing speed (succession of keypresses) and great energy transfer (speed of hammer on string) is very hard to do with a relaxed hand.

The piano itself can aid or hinder the pianist in his effort for clean sound. High end pianos like Steinway or Bechstein have a comfortable mellow sound without using a very heavy action mechanism. Still, in a high end piano the difference between an amateur and talented professional is even more pronounced. This is good, because it clearly reveals bad piano technique. Most people have trouble realising that their sound is "harsh" and "stressful" when playing on low quality pianos.

Medical knowledge tip: relaxing a muscle requires energy consumption. In a cellular level this happens because when a muscle contracts some proteins move to a "tense" state which can only be reverted with further energy consumpion, but at a much lower cost than contracting the muscle. A tired muscle is unable to relax quickly and this is easily seen in electromyography. Conclusion: when you are tense you get easily tired and when you get tired, you get even more tense. This applies especially to very quick succesive muscle contractions, like the ones in piano playing. Try to relax.

PKT