The organ (pipe organ, not electronic organ) is often thought of as an inflexible musical instrument lacking dynamics. Its sound remains unchanged after the key has been pressed, neither tone color, nor volume or pitch can be influenced. Also the keystroke in terms of speed and force is considered less important than in case of a piano, where the keystroke influences tone and volume substantially. However, this does not mean that the keystroke does not matter when playing organ.
Even though the influence of the keystroke on the organ sound is well known amongst organ players, the underlying physics has never been analysed in detail. Some publications mention a small influence of the keystroke on the organ sound, which may be exploited by musicians. However, this is never discussed in detail as the authors focus on other acoustical phenomena. As a passionate organ player, it was important to me to investigate the capabilities of my instrument in detail.
This project is an attempt to generate reasonably systematic measurements with simple means. It differs from other works by considering the organ pipe's response both when the key is pressed and released, for different pitches / frequency ranges. Furthermore, it considers the usual types of action, i.e. tracker, pneumatic and electric addressing of the valves. I did not consider new digital systems as they have not been used so far, even though some measurements have already been published.
