Visitors of the Department of Acoustics at the Fraunhofer Institute for Building Physics in Stuttgart may happen to participate in an organ concert. An organ at an Institute for Building Physics? This is really astonishing. The woman behind the scenes is the scientist Dr. Judit Angster – no organist as may be supposed but physicist by profession. She is dedicated to the scientific acoustics of the organ and of churches as well as to the research of European musical instruments. The installation of a research organ gives her and her team now the chance to investigate the sound and to test sound ideas. "It is a wonderful task to contribute to the research and further development of the knowledge on sound and any problems involved," says Judit Angster with great enthusiasm.
For many centuries, the organ has been considered as the Queen of all instruments. It is the largest and noblest instrument as concerns the equipment. This is why playing the organ is no easy task to learn. But the complexity of sound is incomparable with other instruments, explains Judit Angster: "Each organ is unique in comparison to other musical instruments and may claim absolute individuality as regards the outward appearance and the characteristics of sound. As concerns the richness of tonal quality, tonal range and the dynamics of loudness, it may only be compared to an orchestra."
Everybody who likes to listen to church concerts knows from experience that the sound of each organ is different. There are many factors, which have an impact on the sound quality, to begin with the material of the organ pipes – are they made of wood or metal? – and to end with the room volume, which has a decisive impact on the acoustics (Innovative Design Method for Matching the Pipe Organ to the Acoustics of the Room).
The circulation of the pressurized air – it is called "wind" by the organ – is also important, as it generates the sound in the organ or pipes, and thus has also an influence on the sound. All organ pipes, and these can be a few thousands, must be optimized in sound and adjusted to the room in a way that the generated sound is neither too loud nor too low, but a wonderful mixture of sound is created. The dimensioning of each pipe must be correct to achieve the specific sound. Experts call it scaling. Through voicing will then the beautiful sound character of a pipe, according to the taste of the respective organ building firm be determined (Innovative Methods and Tools for the Sound Design of Organ Pipes).
Despite the difficult room acoustics, since the research organ is installed in a relatively small room and not in a church, concerts could be given, but due to the specific characteristics it will be used for the main purpose: the investigation of questions concerning the techniques and sound. First of all, the transparent design of the organ is remarkable. But the reason is: This transparency allows a view into the interior of the instrument offering the opportunity to make the mechanics visible and to study the complexity of functioning. The wind system of the organ – this is its "lungs" – is something special. It can be switched from a "traditional" to an innovative system and due to this simplified method the pressure control happens directly at the wind chest avoiding pressure losses and wind pressure fluctuations which could harmfully influence the pipe sound.
Moreover, a wind chest of the Great Organ can be exchanged. The wind chest is the tool, on which the pipes are assembled and through which the wind is directly provided to them. The fact that it can be exchanged, allows the testing of innovative valves and pipe layouts. A possible exchange of the upper boards allows the testing of innovative pipe forms as well. This offers the opportunity to test new sound ideas and render them audible.
Due to the special conceptual design the research organ allows investigations directly at the object, simplifying the tasks of the "musical acousticians" considerably, since long-term measurements at an installed organ are sometimes difficult, and it is a complicated task to mount and dismantle an organ. Until now, the researchers investigated organ models in the laboratory in separate working steps. Also newly developed components were tested at models in the laboratory. An example, where a component of a new wind system was realized, is the Stiftskirche in Stuttgart (Development of innovative wind systems).
"The time comes, when you want to transfer a laboratory model into practice," says Judit Angster. "This is why we had the research organ built by the well-known Werkstätte für Orgelbau Mühleisen, Leonberg. My dream is that the achievement of our organ research is the creation of new combinations of physics and music, as well as of science and art for the benefit and delight of people."