Circular Microphone Array Beamforming for Adjustable Directivity
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Solution Overview
Problem
Existing microphone arrangements for recording audio in large sports venues face challenges in achieving high directivity and sound quality due to ambient noise, requiring extensive cabling, manual alignment, and computational costs, while maintaining optimal pickup areas and avoiding obstruction.
Innovation Solution
A microphone array with circularly arranged shotgun microphones, each with an interference tube, forms a common output signal through modal beamforming, allowing adjustable directivity in the horizontal plane and high sensitivity in the vertical direction, eliminating the need for manual alignment and reducing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional microphones are manually aligned to achieve high directivity, then the directivity is improved, but time delay and operator requirements are introduced
Solution Approach 1:
The patent replaces manual mechanical alignment with electronic beamforming. The system uses multiple microphones arranged in an array with electronic signal processing to achieve directional sensitivity without requiring physical positioning or manual alignment. The beam direction is controlled electronically through signal weighting and phase adjustment, eliminating mechanical adjustment time and operator dependency.
2Measurement precision
If more microphones are added to increase directivity, then the directivity is improved, but device complexity and cabling requirements increase
Solution Approach 1:
The patent combines multiple microphone signals electronically through beamforming processing. Instead of requiring separate physical connections for each microphone to achieve directional coverage, the system merges the signals through electronic weighting and summation, reducing the need for extensive cabling while maintaining improved directivity through cooperative signal processing.
3Ease of operation
If fixed microphone placement is used to simplify setup, then ease of operation is improved, but optimal pickup area coverage is reduced
Solution Approach 1:
The patent implements dynamic beam steering capability where the directional sensitivity of the microphone array can be electronically adjusted to track moving sound sources. The system maintains simple fixed physical placement while achieving adaptive coverage through real-time electronic control of beam direction, allowing the pickup area to dynamically follow the position of sound sources such as a football.
4Adaptability or versatility
If larger horizontal pickup area is used to cover more azimuth angles, then adaptability is improved, but vertical pickup area increases causing noise from upper tiers
Solution Approach 1:
The patent creates directionally selective sensitivity patterns through beamforming, concentrating the pickup area in specific azimuth and elevation directions. The system achieves wide azimuth coverage by electronically steering narrow beams across different directions, maintaining high selectivity in the vertical dimension to reject noise from upper tiers while covering the required horizontal area through sequential or simultaneous beam positioning.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The microphone array achieves high directivity with adjustable sensitivity across a wide azimuth angle, minimizing noise interference and maintaining sound quality, while being contactless and computationally efficient, suitable for capturing multiple sound sources simultaneously.
Implementation Method 1
each with an interference tube and a microphone capsule exhibiting a preferred direction of high sensitivity towards the interference tube
Implementation Method 2
The common output signal is obtained by modal beamforming
Data Source
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AI summary
For specific applications, such as e.g. in a sports stadium, a microphone array having particularly high directivity in the vertical direction and a high, but broadly adjustable, directivity in the horizontal direction is provided. The microphone array (100) has a plurality of microphones (110), the output signals of which are combined to produce at least one joint output signal (360). The microphones are directional microphones having a preferred direction of high sensitivity (115) and arranged substantially in one plane on a circle (120) or circle segment, so that each microphone has a different preferred direction of high sensitivity. In this case, the preferred direction of high sensitivity (115) for each of the microphones lies substantially orthogonally in relation to the circle or circle segment. A joint output signal (360) of the microphone array is obtained by beamforming (310,..., 350). The microphone array (100) has an adjustable preferred direction of high sensitivity, wherein the joint output signal (360) contains the sound picked up from this adjustable direction.