swell organ manual
/ˈswɛl ˈɔːɡən ˈmanjuːəl/
n
English · swell organ manual中文 · 强弱音键盘Español · teclado del órgano de expresiónFrançais · clavier de récit
Bedeutung：Keyboard that controls a series of pipes enclosed in a wooden frame (swell box); its movable valves are controlled by a swell pedal to obtain variations in volume.