Hendrik Barfuss

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A research-type 4 T whole-body magnet, built by Siemens AG, Erlangen, FRG, was used to investigate magnetic resonance at high field strengths. Designs for head and body coils operating at 170 MHz are described. Proton images of the human head and body are degraded by dielectric resonances and penetration effects. The nature of the dielectric resonances was(More)
The clinical potential and limitations of magnetic resonance imaging and spectroscopy at 4 T were investigated with the use of a newly constructed system, which has been in use since January 1987. The magnet has a warm bore that measures 1.25 m in diameter, and its homogeneity in a sphere with a diameter of 50 cm is better than +/- 2.5 ppm. It was(More)
Speech extraction in a reverberant enclosure using a linearly-constrained minimum variance (LCMV) beamformer usually requires reliable estimates of the relative transfer functions (RTFs) of the desired source to all microphones. In this contribution, a geometrically constrained (GC)-TRINICON concept for RTF estimation is proposed. This approach is(More)
In this work, a Head-Related Transfer Function (HRTF)-based Robust Least-Squares Frequency-Invariant (RLSFI) beamformer design is proposed. The HRTF-based RLSFI beamformer accounts for the influence of a robot's head on the sound field. The performance of the new HRTF-based RLSFI beamformer is evaluated using signal-based measures and word error rates for(More)
We propose a robust two-dimensional polynomial beamformer design method, formulated as a convex optimization problem, which allows for flexible steering of a previously proposed data-independent robust beamformer in both azimuth and elevation direction. As an exemplary application, the proposed twodimensional polynomial beamformer design is applied to a(More)
In this paper, an unsupervised adaptation algorithm for the microphone array topology of a humanoid robot is proposed, so that the spatial filtering performance is improved. In the given exemplary case, the target suppression (’blocking’) performance of a geometrically-constrained BSS (GC-BSS) algorithm is shown to improve by the adaptation of the array(More)
In this contribution, the problem of broadband acoustic signal extraction is treated as a specific source separation problem, where the desired signal components are to be separated from all remaining undesired components. For this, we exploit the generic TRIple-N Independent component analysis for CONvolutive mixtures (TRINICON) framework. The TRINICON(More)
In a typical human-machine dialogue scenario, the target source and additional interfering sources, located at different positions from the target source, may be active at the same time. Clearly, these interfering sources have to be suppressed in order to establish a successful human-machine interaction. A common strategy is to apply spatial filtering(More)
Uncertainty decoding combines a probabilistic feature description with the acoustic model of a speech recognition system. For DNN-HMM hybrid systems, this can be realized by averaging the DNN outputs produced by a finite set of feature samples (drawn from an estimated probability distribution). In this article, we employ this sampling approach in(More)