Ambisonic Microphone Array Layout for Low Phase Error Capture
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Solution Overview
Problem
Capturing high-quality ambisonic audio requires extensive capital, cabling, and advanced knowledge of A-format to B-format conversion techniques, limiting accessibility and portability for applications like podcasting and virtual reality.
Innovation Solution
An array architecture of microphone capsules is designed with geometric arrangements to reduce acoustic shading and phase errors, allowing for easy capture and conversion of ambisonic audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ambisonic audio equipment and procedures are used, then high-quality ambisonic audio can be captured, but the process requires extensive capital, cabling, and advanced knowledge making it complex and inaccessible
Solution Approach 1:
The microphone array is divided into multiple independent microphone capsules arranged in a geometric pattern, allowing each capsule to function independently while contributing to the overall ambisonic audio capture. This segmentation enables simplified individual components to work together for high-quality recording without requiring complex integrated systems.
Solution Approach 2:
Multiple microphone capsules are nested within a compact geometric structure, with capsules positioned at specific vertices of a regular tetrahedron or other polyhedron. This nesting allows the entire ambisonic array to be contained within a small, portable form factor, eliminating the need for extensive equipment and cabling while maintaining audio quality.
2Volume of moving object
If microphone capsules are placed close together to reduce device size, then portability improves, but acoustic shading and phase errors increase
Solution Approach 1:
The microphone capsules are oriented with their sensitive axes pointing along the diagonals of the tetrahedron edges rather than radially outward. This asymmetric orientation, combined with specific positioning at vertices, creates a configuration where capsules are close together for compactness while their directional sensitivity patterns minimize acoustic shading and phase interference.
Solution Approach 2:
The specific geometric parameters of the tetrahedron (edge lengths, vertex positions, angles between capsule axes) are optimized to achieve the right balance between compact size and audio accuracy. By carefully controlling these parameters, the design maintains reliable audio capture despite the reduced scale.
3Ease of manufacture
If simple equipment is used to reduce cost, then accessibility improves, but the ability to capture high-quality ambisonic audio deteriorates
Solution Approach 1:
The geometric arrangement of microphone capsules inherently performs the complex A-format to B-format conversion through its physical structure. The specific positioning and orientation of capsules at tetrahedron vertices creates natural acoustic interference patterns that directly encode ambisonic information, eliminating the need for complex external processing equipment and expert knowledge while maintaining high audio quality.
Data Source
AI summary
Methods and apparatuses for capturing and encoding ambisonic audio are described herein. An example ambisonic microphone may comprise multiple sets of microphone capsules arrayed around a central axis. Each set may include two microphone capsules positioned along a first axis that is perpendicular to the central axis and two microphone capsules positioned along a second axis that is perpendicular to the central axis and spaced apart from the first axis by a predetermined distance. The multiple sets may be arranged in a sequence such that each set of the multiple sets is rotated about the central axis in the same angular direction by a predetermined angle between adjacent sets in the sequence.