Since 2008, the German Research Foundation “Deutsche Forschungsgemeinschaft” supports a highly interdisciplinary voice research group in Erlangen, called DFG FOR894 with its research topic “Fluid Mechanical Basis of the Human Voice”. The group consists of seven subprojects and is currently in the second project phase. The main research interest is the effect of the dynamic fluid-structures and 3D-tissue-oscillation of the vocal folds. We aim for a better physical understanding of the periodic and noisy parts of phonation. The findings are supposed to explain the motion of the vocal folds and its resulting acoustic signal and thus enable a prediction of the acoustic signal for different boundary conditions. The effects of phonosurgical interference and conservative therapy on vocal fold dynamics and the primary voice signal as well as its modulation in the vocal tract would be predictable and present new, individual possibilities in patients’ treatment in future.
The primary objective of the project is the separation of the different components of voice generation.
The sound fractions which participate in vocal phonation were explored: the mechanically (by vocal fold motions) induced sound, the harmonic parts of the air flow modulation, the turbulence induced sound as well as their meaning for physiologic voice generation. In the first project phase the research unit was able to support the hypotheses that
the volume modulated sound mostly consists of harmonic parts and contributes to good voice quality,
the turbulence induced sound mostly consists of inharmonic parts and deteriorates voice quality,
the mechanically induced sound plays a minor role in voice generation.
Thus, due to the cause-effect chain, an individual treatment planning, based on the gained knowledge, shall be developed in future.
In the second project phase, the effect of the supraglottal part of the vocal tract including the false vocal folds is added to the measurements and models and the influence on voice generation will be clarified.
The following sections review the subprojects which contribute to the research unit FOR 894 and introduce their main objectives.
Since 2008 the research unit is funded by the German Research Foundation DFG and is currently in its second project phase.
University Hospital Erlangen
The Central Project of this Research Group is an organizational and coordinating project. Its major goal is to facilitate and improve the quality of the ongoing research in the DFG group.
Institute of Applied Mathematics II:
The main aim of LSOPT is to use mathematical methods like shape- and material-optimization to determine model parameters of physical models, to be able to realistically resemble complex dynamical patterns.
Chair of Sensor Technology:
Our particular project deals with experimental measurement methods for the analysis of the mechanical material properties of real and artificial vocal folds. Besides, setups for the estimation of the vocal fold collision forces as well as the measurement of the acoustical primary voice signal will be developed.
Institute of Mechanics and Mechatronics:
Technical University Wien
The overall aim of this project is to develop a simulation tool for the human phonation process, which is the complex interaction of fluid-structural mechanics and acoustics, based on solving the partial differential equations on the computer. This simulation tool is then used to answer open questions, such as the importance of vocal fold contact in the phonation.
Institute of Mechanics and Fluid Dynamics:
TU Bergakademie Freiberg
This Project aims to determine the influence of the pattern of glottal motion on the quality of voice (characterized by tonal and noisy sound components). Clinically observed patterns of vocal folds motion are investigated concerning their influence on the flow field and the aeroacoustic field to physically underpin the connection between vocal folds movement and flow and aeroacousitc effects.
Institute of Process Machinery and Systems Engineering / Chair for Fluid Mechanics:
The subproject of iPAT/LSTM focuses on the experimental investigation of the physical basics of the flow-induced vocal fold vibrations and the assoviated generation of the acoustic sources.
Department for Phoniatrics and Pedaudiology:
University Hospital Erlangen
The department for phoniatrics and pedaudiology forms the logical link between the research done on models by the other partners and research done on human or animal larynges as well as clinical application. Thus, the investigation of the vocal fold dynamics and the development of a measurement technique for this purpose are the goals. We provide preprocessed data as input to the research partners.