Does a finger have to strike a key with a vertically downwards motion?
April 16, 2018
As long as the finger’s motion has a “vertical component,” then almost any motion in any direction can serve to cause a note to sound.
In physics, lines of force are often called ‘vectors’. A vector is represented as a line of a certain length and pointing in a certain direction. The length of the line gives an indication of how strong the force is. The direction of the line indicates the primary direction along which the force is acting.
When a ferry boat crosses a river between two points exactly opposite each other, it is only if there is no current in the water than the boat can simply aim for the opposite shore and go in a straight line. If there is a current flowing, let us say, left to right (as seen by the ferry in motion), then as the boat tries to move in a straight line towards the opposite sure, it is at the same time being pushed to the right by the current in the water. If things remain equal the path that the boat will take comes out as a diagonal.
Lines of force that are acting diagonally are often represented as being “reducible” into two “component” vectors. If drawn on a piece of graph paper, one component is displayed vertically and the other horizontally. The vertical component, in our three dimensional example of the ferry boat, is that part of the motion of the ferry boat which is moving directly towards the opposite shore. The horizontal component is that part of the motion of the ferry boat which is going rightwards because of the influence of the river’s current.
The point in this, as far as it relates to piano technique:
If the pianist, instead of moving a finger straight downwards into the key to sound a note, moves instead along a diagonal route, the finger will still depress the key and the key will produce a sound – but only if there is a vertical “component” (see above) to the direction of the finger’s motion. It’s just that not all the energy of the finger is going downwards.
Is there a reason why diagonal motion would be an advantage over vertical motion?
Consider a lever. There is a person at one end exerting a force downwards; there is a fulcrum at some point between the ends of the lever, and a weight that the person is trying to lift attached to the opposite end of the lever.
If the fulcrum is placed nearer the person applying the force, then a smaller downwards motion by that person results in a larger upwards motion by the weight on the other end. Sounds good, but the effort involved is difficult. If, however, the fulcrum is placed nearer the weight, then a longer motion downwards by the person is ‘mapped’ or condensed into a smaller amount of motion upwards by the weight. In other words it makes the effort not only easier, but, and this is the important part, it affords the possibility of more minute control over the motion of the other end of the lever, or in the case of the pianist, finer control over the downward motion of the key. The result: a more accurate and subtle touch. One affording many more nuanced possibilities of execution.