Endfire Linear Array Microphone Directionality Across Frequencies
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Solution Overview
Problem
Traditional linear array microphones face limitations in directionality and performance, especially at low frequencies due to the close spacing of microphone elements, leading to omnidirectional pickup patterns and reduced effectiveness in space-limited environments.
Innovation Solution
The integration of a delay and sum beamformer for higher frequency ranges and a differential beamformer for lower frequency ranges within the same linear array microphone system, allowing for consistent directionality and performance across different frequency ranges by generating beamformed output signals based on audio signals from multiple microphone groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If microphone elements are spaced close together to fit in space-limited locations, then the microphone can be placed in compact environments, but the directionality and performance at low frequencies deteriorates
Solution Approach 1:
The patent divides the frequency spectrum into different bands and applies different beamforming techniques to each band. A first beamforming technique is used for higher frequencies where close spacing is acceptable, while a second beamforming technique is used for lower frequencies to maintain directionality. This segmentation allows the microphone to achieve good directionality across the full frequency range despite compact dimensions.
Solution Approach 2:
The patent dynamically selects or adjusts beamforming parameters based on frequency content. The system adapts its beamforming approach according to the frequency range of the incoming sound, switching between different processing modes to optimize directionality at each frequency band. This dynamic adaptation enables consistent directional performance across varying frequency conditions.
2Device complexity
If traditional beamforming is used with closely spaced elements, then the microphone structure remains compact, but the pickup pattern becomes omnidirectional at low frequencies
Solution Approach 1:
The patent applies different beamforming characteristics to different frequency ranges. For low frequencies, a specialized beamforming technique is applied that is optimized for maintaining directional pickup patterns despite the small element spacing. For higher frequencies, conventional beamforming suffices. This local optimization ensures that each frequency band receives the appropriate processing to achieve the desired pickup pattern.
Solution Approach 2:
The patent changes key beamforming parameters such as weighting coefficients, delay values, and combination methods based on the frequency range. By adjusting these parameters dynamically or through frequency-dependent filtering, the system maintains controlled pickup patterns across all frequencies while keeping the physical structure compact.
Data Source
AI summary
Endfire linear array microphone systems and methods with consistent directionality and performance at different frequency ranges are provided. The endfire linear array microphone includes a delay and sum beamformer and a differential beamformer. The delay and sum beamformer may produce pickup patterns with good directionality at higher frequency ranges, but cause the pickup patterns to become more omnidirectional at lower frequencies. The differential beamformer may produce pickup patterns with good directionality at lower frequencies. By combining the delay and sum beamformer and differential beamformer within the linear array microphone, the overall directionality of the linear array microphone may be maintained at different frequency ranges while using the same microphone elements.