Modifications of the Vocal Tract and Determination of Associated Resonance Properties During Singing Via Real-Time Volumetric Magnetic Resonance Imaging

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The function of the vocal tract during singing is still not completely understood. This grant application deals with dynamic real-time examination of vocal tract modifications during singing via magnetic resonance imaging (MRI). Our aim is to measure professional singers in a high field MR system during singing with the help of a three-dimensional sequence.In the scope of the first grant we successfully improved the temporal resolution of the acquired pictures in the mid-sagittal plane from 8 to 24 frames per second and analyzed dynamic changes of the vocal tract configuration in dependence of voice type, register and genre of singers. Laryngoscopic examinations with a high speed camera suggest that register changes also lead to modifications in the lateral-medial dimension that cannot be perceived in our currently acquired plane. It is to be assumed that such changes are relevant for resonance, i.e. changes in formant frequencies and bandwidths. Thus, an extension of the current MR sequence into a full three dimensional volume acquisition is required.In the course of this grant we have the following program:- Development and implementation of a three-dimensional MR volume acquisition and implementation of an image reconstruction algorithm. - Implementation of a semi-automatic segmentation method to create models of the vocal tract from dynamic real-time data.- Adaptation of the previously applied sequence into a two-dimensional multi-slice method and comparison of the 2-D and 3-D method.- Measurement of 20 professional singers of different type- Comparison of resonance properties of the vocal tract using three different sources :1) mathematical models derived from the MR data, 2) three dimensional plastics of the vocal tract from the same segmented MR data that are printed via rapid prototyping, and 3) inverse filtering of the audio signal.The proposed research program will help reveal the connections between specific modifications of the vocal tract and related acoustic effects in respect to different singing functions.