Historic church organs such as the Walcker organ in Ilmenau are fascinating, complex sound machines and important testimonies to European cultural history. In contrast to many instruments that have slowly changed over the centuries, church organs retain their basic principles while constantly adapting to new technologies. Even the earliest organs of the Middle Ages combined elaborate craftsmanship with natural materials such as wood, leather and metal pipes. However, their organic nature also makes them particularly difficult to preserve, as their materials age and sensitive mechanical systems wear out. Many historical organs have therefore already been lost due to wars, fires or natural wear and tear - and surviving instruments are rare treasures of European musical culture.
An interdisciplinary research team within the European project MusicSphere, coordinated by the Centre for Research & Technology Hellas (CERTH) - Information Technologies Institute, is therefore developing digital methods to precisely capture the construction, mechanics, and sound of such instruments. The aim is to support restoration processes and to preserve these valuable cultural artifacts beyond their physical lifespan in the form of digital twins.
Twelve partners from Belgium, Germany, Greece, Spain, and Cyprus - bringing together expertise in acoustics, audiovisual digitization, AI-supported data analysis, organ building, and cultural heritage management - are collaborating over a period of three and a half years to create highly detailed digital 3D models of historic wind instruments.
To achieve this, the researchers combine 3D technologies, acoustic analysis, and immersive digital experiences. Their goal is to make organs and other historical instruments accessible for scientific study in immersive virtual environments while also enabling broader audiences to experience them digitally Documenting the sound of these instruments presents a particular challenge, as it strongly interacts with the architecture of the surrounding space. In Ilmenau, two local research partners with longstanding expertise in digital audio technologies - the Fraunhofer IDMT and TU Ilmenau - have therefore joined forces to capture the acoustic characteristics of both the instrument and the church interior as precisely as possible.
The importance of such research is illustrated by a well-known example from recent history: "The fire in Notre-Dame Cathedral in Paris in April 2019 not only destroyed numerous artworks but also changed the unique acoustics of the building," explains Dr. Stephan Werner, head of the Electronic Media Technology Group and MusicSphere sub-project leader at TU Ilmenau.
Only because the acoustics expert Brian F. G. Katz from Sorbonne University had measured the sound of Notre-Dame in great detail years before the devastating fire was it possible to reconstruct its historical acoustics during the restoration.
At the beginning of March, Dr. Lukas Treybig and Georg Stolz from TU Ilmenau’s Electronic Media Technology Group, together with Dr. Florian Klein and Andrew McLeod from Fraunhofer IDMT, conducted initial acoustic measurements of both the organ and the interior of St. Jacob’s Church in Ilmenau. For this purpose, they used an autonomously navigating acoustic measurement robot developed jointly with the Ilmenau-based company MetraLabs GmbH to precisely capture the sound of the organ and its interaction with the surrounding environment. Georg Stolz explains:
With our microphones we can measure both individual notes from different organ stops and the acoustics of the room itself. This allows us to analyze from which direction and at what time sound reflections return. Based on these measurements, we can later derive and simulate the remaining notes.
The team jointly tested and refined their methodology in Ilmenau in preparation for further recording sessions on an organ in Belgium, explains Dr. Stephan Werner.
The challenge is to separate the organ as a large sound source from the acoustics of the room and to precisely capture the variability of the spatial acoustics. The data collected in Ilmenau can then be used by our partners - the University of Málaga and Fraunhofer IDMT - to simulate the spatial sound and the organ pipes of the Belgian instrument. These simulation data will subsequently be provided to the two organ builders involved in the project, enabling them to reconstruct individual organ pipes with the correct acoustic characteristics using the digital twin.
At the same time, researchers at Fraunhofer IDMT are developing AI methods for automatic music transcription and sound synthesis. These approaches aim to faithfully reconstruct the historical sound characteristics so that they can later be experienced in virtual instruments as well as immersive VR and AR applications.
The researchers in Ilmenau see significant potential in MusicSphere for musicological research, restoration, and cultural communication. High-precision digital datasets could make it possible to document historical organs authentically, use them in research and teaching, and present them to visitors in virtual exhibitions. Even instruments that survive only in fragments could be digitally reconstructed.
One particularly ambitious objective of the twelve project partners is the digitization of the ancient Hydraulis, the earliest known predecessor of the pipe organ. Discovered in 1992, the fragment - now exhibited in the Museum of Dion in Greece - is incomplete and no longer playable. Through the technologies and methods developed in the MusicSphere project, missing components could be virtually reconstructed, physical properties modeled, and the acoustics of the original performance spaces simulated. This would allow the Hydraulis to be experienced digitally around the world - opening a new window onto ancient music and contributing to the preservation of cultural heritage.
The first reasearch activities in Ilmenau were also experienced firsthand by young participants from the Excellence school network MINT-EC, who had traveled from across Germany to TU Ilmenau for a five-day science camp. The experience proved to be a win-win situation: the students gained direct insights into cutting-edge research, while TU Ilmenau and Fraunhofer IDMT may in the future benefit from motivated young researchers.
Angelina from the Johannes-Kepler-Gymnasium in Lebach (Saarland) describes her impressions:
For us young people, it’s important to think about how we can shape our future with technologies like these. I think it’s really cool that we can try things ourselves here and experience real research. That’s something special - you don’t get that at school.
The MusicSphere has received a total of ¤6 million in funding from the EU Horizon Europe program under grant agreement No. 101233618, including ¤370,000 for TU Ilmenau.
The content of this article reflects only the author’s view; the EU is not responsible for any use of this information.
