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Richtungsdetektion mit dem Eigenmike Mikrofonarray

Authors Brandner, M.
Year 2013
Thesis Type Bachelor's thesis
Topic Spatial Audio
Keywords Aufnahmetechnik
Abstract Within this thesis the feasibility of directional detection of sound sources through an correlation algorithm is treated using a spherical microphone array called Eigenmike. The proposed detection algorithm is based on correlating synthesized spherical wave spectra with a spherical spectrum obtained from measured impulse responses. The synthesized spectra are calculated based on knowledge of sound propagation and boundaries within the measurement arrangement. Measurement signals were recorded on 612 positions around the microphone array with a fixed radial distance. To fulfill the conditions for a simulated free field situation the measurement was set up within certain calculated distances and also the part of the recorded impulse responses which holds the direct sound is windowed. With the Fourier transfomed pressure values the calculation of the spherical wave spectrum for a specific source position is possible. The result of a correlation with a synthesized spectrum gives a data vector, where each index holds directional information and a normalized value of intensity. High values should be obtained for the data indexes with the directional information nearest to the sought direction of the sound source. In the ideal case the highest value gives the source direction. The results show an limited frequency resolution as expected, due to the arrangement of the microphones on the sphere. The functionality of the algorithm in the mid frequency range from 1 to 5kHz is fully given for the idealized instance. For lower and higher frequencies the angle error increases and detection lacks accuracy. Thus the results lead to the conclusion that the directional detection with the proposed algorithm is feasible within the known boundaries.
Supervisors Sontacchi, A.