AES San Francisco 2010
Paper Session P6

Friday, November 5, 9:00 am — 10:30 am (Room 220)

Paper Session: P6 - Microphone Processing

Jon Boley

P6-1 Digitally Enhanced Shotgun Microphone with Increased DirectivityHelmut Wittek, SCHOEPS Mikrofone GmbH - Karlsruhe, Germany; Christof Faller, Illusonic LLC - Lausanne, Switzerland; Christian Langen, SCHOEPS Mikrofone GmbH - Karlsruhe, Germany; Alexis Favrot, Christophe Tournery, Illusonic LLC - Lausanne, Switzerland
Shotgun microphones are still state-of-the-art when the goal is to achieve the highest possible directivity and signal-to-noise ratio with high signal fidelity. As opposed to beamformers, properly designed shotgun microphones do not suffer greatly from inconsistencies and sound color artifacts. A digitally enhanced shotgun microphone is proposed, using a second backward-oriented microphone capsule and digital signal processing with the goal of improving directivity and reducing diffuse gain at low and medium frequencies significantly, while leaving the sound color essentially unchanged. Furthermore, the shotgun microphone’s rear lobe is attenuated.
Convention Paper 8187 (Purchase now)

P6-2 Conversion of Two Closely Spaced Omnidirectional Microphone Signals to an XY Stereo SignalChristof Faller, Illusonic LLC - St-Sulpice, Switzerland
For cost and form factor reasons it is often advantageous to use omni-directional microphones in consumer devices. If the signals of a pair of such microphones are used directly, time-delay stereo with possibly some weak level-difference cues (device body shadowing) is obtained. The result is weak localization and little channel separation. If the microphones are relatively closely spaced, time-delay cues can be converted to intensity-difference cues by applying delay-and-subtract processing to obtain two cardioids. The delay-and-subtract processing is generalized to also be applicable when there is a device body between the microphones. The two cardioids could be directly used as stereo signal, but to prevent low frequency noise the output signals are derived using a time-variant filter applied to the input microphone signals.
Convention Paper 8188 (Purchase now)

P6-3 Determined Source Separation for Microphone Recordings Using IIR FiltersChristian Uhle, Fraunhofer Institute for Integrated Circuits IIS - Erlangen, Germany; Josh Reiss, Queen Mary University of London - London, UK
A method for determined blind source separation for microphone recordings is presented that attenuates the direct path cross-talk using IIR filters. The unmixing filters are derived by approximating the transmission paths between the sources and the microphones by a delay and a gain factor. For the evaluation, the proposed method is compared to three other approaches. Degradation of the separation performance is caused by fractional delays and the directivity of microphones and sources, which are discussed here. The advantages of the proposed method are low latency, low computational complexity, and high sound quality.
Convention Paper 8189 (Purchase now)

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