These pages comprise a dictionary of terms relating to the pipe organ. Please keep definitions to a few sentences, and do not include pictures or sound clips. When more space is needed for a term, a new page can be created for it. Valve Valvular Reed Ventil Ventil Chest Violone - A string stop named after the orchestral double bass, and usually appearing at 16' on the manuals or at 16' or 32' in the pedal. It is normally of metal and of moderate scale. Voicing [noun] - the art, craft and science of making all the pipes in the organ speak properly.