Two-foot (organ pitch)
A high organ pipe length.
What it means
Two-foot designates, in the organ, a stop whose longest open pipe measures about two feet. It sounds two octaves higher than notated: a fingered key c' sounds as c'''. In the system of foot-pitch numbers, the two-foot thus stands above the four-foot, which lies an octave above notation, and above the eight-foot, which coincides in sound with the notation. Two-foot stops carry names such as Octave, Principal, Flute, or Waldflöte, depending on construction and tradition.
Musical use
High stops are rarely used alone but as part of a build-up. In classical registration, eight-, four-, and two-foot together form the principal chorus, which acts like a reinforced overtone series: the fundamental voice carries, the higher stops give brilliance and clarity. A two-foot makes the voice leading more transparent and lets fast passages stand out more clearly. Alone, or combined with a flute, it can serve as a bright solo voice, for instance for a cantus-firmus part in a high register. In dense chords it easily becomes shrill.
Performance practice
Build a registration from the bottom up: choose the fundamental voice first, then add four- and two-foot, checking each time whether the sound becomes clearer or merely louder. With high stops, keep the spacing wide and avoid close chords in the treble register. Note that the topmost octave of many stops repeats, that is, falls back on lower pipes — this changes the sound and is not a fault. Note registrations with foot-pitch numbers rather than only with names, so that they remain transferable to other instruments, and check in advance exactly where the repeat point lies in the treble register.