Rene Derkx was born in 1974 in Ysselsteyn, The Netherlands. He received the B.S. degree (cum laude) in electrical engineering in 1998 from the Eindhoven Polytechnic, and the M.S. degree (cum laude) in electrical engineering in 2000 from the Eindhoven University of Technology. In 2000, he joined Philips Research Laboratories in Eindhoven, where he worked on acoustic echo and noise control, active noise control, dereverberation and sound reinforcement. Currently, his main field of research is in the area of small microphone arrays.
Abstract: Acoustic zooming aims at increasing and decreasing the perceived distance of the sound-image by varying a zoom-parameter. Previously proposed superdirective acoustic zooming techniques focus on controlling the directivity-factor of the constructed beampattern by varying this zoom-parameter. As a result, these zooming techniques are only consistent in the case of (spherically) isotropic interferences. In practical situations however, often directional interferences (mainly coming from a single direction) are present. To have a
consistent behaviour of the acoustic zooming, we will propose a new zooming technique that is based on a novel first-order beampattern construction. The beampattern is constructed in such a way that for every angle, the response is monotonically increasing/decreasing in a consistent way with the zooming-parameter.
Abstract: For unobtrusive capturing of acoustic breathing signals during sleep, a microphone can be placed in the vicinity of the person. As breathing signals are generally very weak compared to the intrinsic noise of the microphone, the resulting signal-to-noise ratio (SNR) is low. We present a de-noising technique for the enhancement of acoustic breathing signals captured with a microphone. As the intrinsic noise of the microphone is stationary, we can use standard spectral subtraction schemes with stationary noise-floor estimators. For bad SNR conditions however, these techniques suffer from musical tones. To remove these musical tones, we apply median filtering in the standard spectral subtraction scheme. Furthermore, an alternative solution is proposed that has a very low computational complexity.
Abstract: An azimuth steerable first-order superdirectional microphone response can be constructed by a combination of a monopole and two orthogonal dipole microphones. We derive a novel adaptive null-steering scheme based on the generalized sidelobe canceller (GSC), aiming to reject a single directional interference. To fully exploit the three microphone inputs, we use the extra degree of freedom to optimize the directivity index. Besides closed-form expressions for this optimal null-steering, we present a novel gradient-search strategy.
