Page 12 - 2017Spring

Acoustics of Organ Pipes and Future Trends in the Research
Knowledge of the acoustics of organ pipes is being adopted in applied research for supporting organ builders.
Introduction
The pipe organ produces a majestic sound that differs from all other musical in- struments. Due to its wide tonal range, its ability of imitating the sound of vari- ous instruments, and its grandiose size, the pipe organ is often called the “king of musical instruments” (Figure 1). The richness and variety of sound color (timbre) produced by a pipe organ is very unique because of the almost uncountable pos- sibilities for mixing the sounds from different pipes. According to the art of sound generation, there are two kinds of pipes in the organ that are similar in function to other wind instruments: flue (labial) pipes and reed (lingual) pipes. Although this article focuses on sound excitation by flue pipes, the role of reed pipes is brief- ly mentioned (see Figure 2). The article also shows how the connection between sound character and pipe shape and dimensions can be understood, and it also considers the trends in the research that focus on helping organ builders in their practical work.
Email:
rucz@hit.bme.hu
András Miklós
Postal:
Fraunhofer-Institut für Bauphysik (Fraunhofer Institute for Building Physics IBP) Nobelstrasse 12, 70569 Stuttgart, Germany
Steinbeis Transferzentrum Angewandte Akustik Weilstetter Weg 36, 70567 Stuttgart, Germany
Email:
AkustikOptik@t-online.de
Judit Angster
Postal:
Fraunhofer-Institut für Bauphysik (Fraunhofer Institute for Building Physics IBP) Nobelstrasse 12, 70569 Stuttgart, Germany
Email:
judit.angster@ibp.fraunhofer.de
Péter Rucz
Postal:
Budapest University of Technology and Economics Magyar tudósok krt. 2, 1117 Budapest, Hungary
Structure of the Pipe Organ
A sketch of a pipe organ is shown in Figure 3. Its main parts are the windchest with the pipes, the wind system, and the control system (keyboard, tracker action, and drawstops; Figure 2). The pipes are organized on the windchest according to note and timbre. A set of pipes producing the same timbre for each note is called a rank and each key on a pipe organ controls a note that may be sounded by differ- ent ranks of pipes, alone or in combination (see http://acousticstoday.org/organ_stop; for a demo, see http://acousticstoday.org/rank).
ab
Figure 1. a: Research organ in the Fraunhofer Institute of Building Physics IBP in Stuttgart, Germany, built by Mühleisen (Leonberg, Germany) in 2011. The pedals can be seen under the bench. Photo by Roman Wack. b: Pipe organ in the Stiftskirche in Stuttgart, Germany, built by Mühleisen (Leonberg, Germany) in 2004. The frontal pipes can be clearly seen. Photo by Theo Holder.
10 | Acoustics Today | Spring 2017 | volume 13, issue 1 ©2017 Acoustical Society of America. All rights reserved.