Before a bassoon leaves the workshop of instrument makers Wilhelm Heckel GmbH of Wiesbaden, a professional musician subjects it to quality control. He checks the clarity of its sound, makes sure that all its notes are accurately pitched and analyses the spectrum of its overtones. Several weeks ago, this procedure began to be supported by a computer programme developed at the Institute for Aerospace Engineering at the Technische Universität Dresden. The programme was designed by the engineer Timo Grothe and is based on ideas developed together with the researcher Johannes Baumgart from the Institute of Scientific Computing at the Technische Universität Dresden. This a further example of the cooperative work that has been carried out by the University and musical instrument makers for a number of years.

Timo Grothe belongs to a small group of researchers founded some years ago by Roger Grundmann, Professor of Numerical Fluid Mechanics: their purpose is to investigate the acoustics of wind instruments. In his Ph.D. thesis, Grothe examines bassoon geometries and the influence they have on the sounds produced. To ensure the reproducibility of conditions when several different instruments are being tested, an "artificial mouth" is used to "play" them. The sounds are recorded, and by analysing their sound spectra, it is possible to distinguish the instruments' characteristics without the intrusion of random variables.

"Of course, a computer programme cannot replace the well-trained human ear and years of experience", says Grothe, "However, this tool offers instrument makers at traditional companies such as Heckel the ability to make retrospective comparisons between instruments long after the subjective impressions of their sounds have faded."
Professor Grundmann's group was the first to calculate the airflow inside a bassoon while being played. Using simulated prototype designs, a new bocal for the bassoon was developed that maximises the ease of playing by reducing blowing resistance. The new geometry for the bocal was patented in 2005 and is now sold worldwide.

The Institute for Aerospace Engineering is planning to undertake more research on the acoustics of wind instruments. The goal is to understand the complex behaviour of the sound source, and to thereby help instrument makers design the subtle details that make instruments produce sounds to match or exceed the expectations of their musician customers.
This work will continue to be based on close collaboration between researchers, instrument makers and musicians.

Author: Martin Morgenstern

Photodownload (3,3 MB), Photographer: Fa. Wilhelm Heckel GmbH

Further details:
Timo Grothe
Phone: +49 351 463-38096