Binaural Rendering with Measured Room Responses: First-Order Ambisonic Microphone vs. Dummy Head
Markus Zaunschirm, Matthias Frank, Franz Zotter
Abstract
To improve the limited degree of immersion of static binaural rendering for headphones, an increased measurement effort to obtain multiple-orientation binaural room impulse responses (MOBRIRs) is reasonable and enables dynamic variable-orientation rendering. We investigate the perceptual characteristics of dynamic rendering from MOBRIRs and test for the required angular resolution. Our first listening experiment shows that a resolution between 15 ∘ and 30 ∘ is sufficient to accomplish binaural rendering of high quality, regarding timbre, spatial mapping, and continuity. A more versatile alternative considers the separation of the room-dependent (RIR) from the listener-dependent head-related (HRIR) parts, and an efficient implementation thereof involves the measurement of a first-order Ambisonic RIR (ARIR) with a tetrahedral microphone. A resolution-enhanced ARIR can be obtained by an Ambisonic spatial decomposition method (ASDM) utilizing instantaneous direction of arrival estimation. ASDM permits dynamic rendering in higher-order Ambisonics, with the flexibility to render either using dummy-head or individualized HRIRs. Our comparative second listening experiment shows that 5th-order ASDM outperforms the MOBRIR rendering with resolutions coarser than 30 ∘ for all tested perceptual aspects. Both listening experiments are based on BRIRs and ARIRs measured in a studio environment.