A Spatial Composition


for two pioneering instruments


Helder Tenor Recorder & Icosahedral Loudspeaker


Semaphor was developed in several research sessions with the IKO at Hybrid Lab Berlin, The Cube at IEM Graz and the Media Art Lab ESC Graz.

We also exchanged data like sound files and texts, ideas on scores and recordings digitally and met online over a period of time from 2017 - 2018.

During this time we were funded and supported by several institutions which made travelling, studio rent, purchase of equipment and living possible.

We were giving lectures on our compositional process at the annual meeting of the artistic doctoral school in Graz and on several symposia e.g the IKO Summer School (OSIL) 2018 were we also gave a first listening insight into the first four minutes of the research in progress piece.

From 2018 we started discussing and experimenting with microphones, recording situations and different spaces to develop an adequate procedure for the documentation of the  piece. Dr. Dipl. Ing Frank Schultz (sonible, IEM, today University of Rostock) took on the task and supported us over months, trying to understand the peculiarities of the piece and how to find the  golden ratio between performance, recording space and recording equipment. As this had not been done before the very process was an adventure and a became part of the artistic research Lab situation.

We are very grateful for Frank's meticulous work.



© sengpielaudio

Photo 102: Eberhard Sengpiel recording system

After experimenting with several positions of the microphones, Frank Schultz chose a distance of 4.80 metres perpendicular to the IKO's axis. Aesthetically, this solution was the most sensible, because the diffusion and direct proportion were exactly the same and fit perfectly with the acoustics of the CUBE. The 90-degree angle and short distance of the microphones to the IKO made us rethink Susanne's live performance spatial positions, and most positions were adjusted for each section to get the most out of the audio recording. In order to meet the requirements for living room listening conditions, we slightly adjusted dynamics to a range of 50 decibels for the album.


We also recorded “Semaphor” in headphone stereophony with a dummy head which had been tested several times in live performances. For this recording, we chose the same position as the microphones in the equivalence stereophony recording. To fully perceive this composition as if “live in concert”, we kept the original and intended dynamics of approximately 72 decibels. Although binaural recordings have been made in the past of electronic spatial music, the combination with a live performer is quite unique and therefore its documentation is an important testimony of our time. 



The final step of our collaboration was to find a way to document our piece in a way that would meet the requirements of a spatial composition and present its depth and dimension. Although we recorded and videoed our work sessions and performances, Susanne's biggest goal was to include 'Semaphor' on her debut album. When she first came up with this idea, we knew that we could not just go into a standard recording studio, but that we would need both special equipment and a mastermind to make this recording happen. Frank Schultz came up with two ideas that we could use in the CUBE studio at the IEM in Graz: a stereo version in equivalence stereophony, and a headphone stereo version using a dummy head.


For the stereo version in equivalence stereophony, we used the Eberhard Sengpiel (EBS) recording system with two condenser microphones at 90-degree angle, at a distance of 25cm.