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Acoustic Centering and Rotational Tracking in Surrounding Spherical Microphone Arrays

Authors Deboy, D.
Year 2010
Thesis Type Diploma thesis
Topic Spatial Audio
Keywords musical acoustics, audio recording, signal processing, binaural
Abstract This diploma thesis considers the development and testing of methods applicable for the analysis of radiation patterns from real-world instruments. The goal is the estimation of geometric parameters of the radiation-patterns from instrumental sounds. These parameters shall be retrieved from sound-radiation data that have been captured by a surrounding microphone array. In a first step, solution strategies for different problems are developed that arise in the recording situation of surrounding microphone arrays. For example, the correct orientation of the analysis data using a spherical microphone array of which the orientation is known imprecisely. Moreover, a major goal is to find simple measures for detecting the acoustical center of a sound source inside the microphone array. For a decomposition of the measured data into spherical harmonics, we assume a limited spatial bandwidth due to the finite number of discrete angular microphone positions. This assumption yields problems whenever a sound source is not perfectly located at the center of the array. A cost function shall be minimized in order to find a center of decomposition that is superior for decomposition in the analysis. Furthermore, this work investigates the tracking of a rotating sound source using cor- relation measures. For this purpose successive sound-radiation data is compared by rotational matching.
Supervisors Zotter, F.