Mechanical Pipe Organ Actions and why Expression is Achieved with Rhythmic Variation Rather than Transient Control
A. R. Woolley · 2010
Whether mechanical organ actions allow organists to control the way in which they move the key and thus influence the transients has been discussed for many decades and this is often given as their main advantage. Some characteristics of mechanical pipe organ actions, notably pluck (the initial resistance felt as the pressure difference across the pallet valve is overcome, and which, due to flexibility in the action, also results in the pallet not starting to open until the key has moved a significant distance), make it difficult for the player to control the key movement and thus the transient. This project looks at how organists use rhythm and timing to play expressively. This can be through the use of deliberate “figures”, or the player may be unaware that they are making such variations. These variations in style lead to clear groupings of the pressure rise profile under the pipe and thus limit the amount of transient control possible. Informal listening tests suggested that the transient variation measured were only discernable by the most highly trained listeners and may be less important than timing.