Organ flue pipes divide into open-open and open-closed acoustic types

Evidence

There are two basic types of organ flue pipe: those that are open and those that are stopped at the end farthest from the flue itself (see Figure 4.12). The flue end of the pipe is acoustically equivalent to an open end. Thus the open flue pipe is acoustically open at both ends, and the stopped flue pipe is acoustically open at one end and closed at the other. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1152

Categorization

• DEFINE: Clarifies the open/stopped pipe distinction in terms of acoustic end conditions rather than construction.
• corroborated: 2 independent passages support this claim — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1152
• XREF: connects to: Open and stopped organ pipes correspond to open-open and open-closed acoustic tubes. — David Howard, Jamie Angus, coustics and Psychoacoustics, 1181; Woodwind flue instruments act acoustically as pipes open at both ends — David Howard, Jamie Angus, coustics and Psychoacoustics, 1214