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Plug-In for Frequency-Dependent Control of Microphone Polar Patterns.

Authors Deppisch, T.
Year 2018
Thesis Type Audio Engineering project
Topic Audio Signal Processing
Abstract Arbitrary first-order polar patterns can be created by weighted summation of the outputs of front and back diaphragm of a dual-diaphragm microphone. If the output signals of both diaphragms are accessible inside a digital audio workstation (DAW), the polar pattern can be (re)adjusted at any time and is not limited to discrete, predefined patterns. This work describes the development of an open-source software plug-in, which allows for the frequency-dependent control of a dual-diaphragm microphone's polar pattern in up to five adjustable frequency bands. Two approaches for creating the underlying filterbank are presented: A linear-phase FIR approach and an IIR approach. Diffuse-field and free-field equalization of synthesized polar pattern signals are described exemplarily for a particular microphone and an algorithm for automatic polar pattern optimization is designed, based on the intensity of a target signal. The characteristics of dual-diaphragm microphones are investigated by employing a physical model. Filters for equalization of the proximity effect are derived by this model.
Supervisors Frank, M.