Pipe Organ Mechanical Actions
There has been much discussion over the last few decades about the extent to which organists can influence the transients of the pipe speech in organs using mechanical actions by the way in which they move the key. Previous experiments have used laboratory models of single notes and may not represent what players do whilst playing music.
Some of the characteristics of mechanical actions, notably pluck (the initial resistance as the pressure difference across the pallet valve is overcome), mean that it difficult for the player to control the movement of the key, and flexibility in the action run means that components of the action twist, bend and compress until the pluck is overcome and the pallet valve under the pipes springs open to catch up with the rest of the action.
Measurements were taken using infrared LED sensors and laser sensors measuring the movements of the key and the pallet. A laboratory model was built to clarify specific points.
The results showed that players did vary the way in which they moved the key but the difference was almost exclusively in the 'flexible' part of the action movement before the pallet started to open. Once the pallet started opening there was very little variation in movement during this critical stage. Measurements on the model showed that, in any case, the pressure in the groove reached a peak very early in the pallet movement.
Variations in the rhythm of playing were very apparent even though the players did not think that they were changing it.
Whilst it appears that an ability to influence the transient is not a significant feature of mechanical pipe organ actions there are many aspects still to be studied.
The Arts and Humanities Research Council has funded a three year project starting in September 2008 with four main objectives:
- to continue the work on establishing how individual action components contribute to the "touch" of an organ action and which characteristics are of most importance to the player;
- to study the use of rhythm and timing as a means of expression in organ playing whether or not the player is aware of it;
- to study the airflow through the windchest and particularly through the pallet opening in order to better predict the magnitude of pluck;
- to work with the Fraunhofer Intitut für Bauphysik to refine their computer program that predicts the characteristics of actions.
The project has a formal link with the Fraunhofer Intitut für Bauphysik, Stuttgart, and has established very active links with the Göteborg Organ Art Centre (GOArt) and the Eastman School of Music, Rochester NY.
The research team comprises Dr Alan Woolley as full time Postdoctoral Research Fellow, Professor Murray Campbell as Principal Investigator and Dr John Kitchen as Co-investigator.
