Symmetrical Microphone Array for Off-Axis Audio Pickup
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Solution Overview
Problem
Existing audio signal processing systems, such as conference systems, face challenges with 'off-axis' sound signal attenuation and 'white-noise-gain' issues due to the design of microphone arrays, leading to poor signal quality and noise interference.
Innovation Solution
An audio signal processing apparatus with a symmetrical arrangement of three directional microphones forming an included angle of 120 degrees, where the axes are in the same horizontal plane, and distances between microphones are kept close (0-5 mm), allowing for linear combination and dynamic selection of the best pickup direction based on signal-to-noise ratio using a specific matrix and algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If three directional microphones are arranged in an octopus structure with 120-degree included angles, then the device complexity is reduced and manufacturing is simplified, but off-axis sound signals experience severe attenuation leading to poor signal quality
Solution Approach 1:
The patent segments the sound pickup function across three separate directional microphones arranged symmetrically, with each microphone handling a specific angular sector. This segmentation allows the system to maintain simple manufacturing while improving overall pickup coverage and reducing off-axis attenuation through coordinated processing of signals from multiple segments
Solution Approach 2:
The patent transitions from a single-direction pickup approach to a multi-dimensional angular coverage by arranging three microphones in a vertical plane with 120-degree spacing. This dimensional arrangement, combined with specific spacing (0-5mm), creates a three-dimensional pickup pattern that eliminates off-axis attenuation while maintaining manufacturing simplicity
2Measurement precision
If three omnidirectional microphones are used to form a ring structure with 2cm spacing, then off-axis attenuation is reduced, but low-frequency white noise is amplified resulting in white-noise-gain problems
Solution Approach 1:
The patent applies local quality by using directional microphones with specific pickup patterns rather than omnidirectional microphones. Each microphone's directional characteristics are optimized for its specific angular position, allowing the system to achieve uniform omnidirectional coverage through coordination while maintaining noise rejection capabilities at each local position
Solution Approach 2:
The patent introduces asymmetry in the vertical spacing arrangement (0-5mm distances) and directional characteristics of microphones to create a pickup pattern that naturally suppresses low-frequency white noise while maintaining off-axis signal quality, breaking the symmetry that causes uniform noise amplification in conventional ring structures
3Device complexity
If directional microphones are positioned at ends with 120-degree included angles, then the device structure is simplified, but noise signals from directions other than the speaker direction are completely picked up without attenuation
Solution Approach 1:
The patent makes each directional microphone serve multiple functions: primary sound pickup from its designated direction, secondary noise detection from other directions, and participation in forming the overall omnidirectional pickup pattern. This multi-functionality allows simple structure to achieve both wide coverage and noise suppression
Solution Approach 2:
The patent implements feedback through signal processing that combines outputs from all three microphones, using the spatial and temporal relationships between signals to identify and suppress noise while enhancing speaker voice. The close spacing (0-5mm) enables precise feedback-based noise cancellation
Data Source
AI summary
An audio signal processing apparatus is provided by the present disclosure, and includes: multiple microphones; and every two of the multiple microphones being arranged in close proximity to each other, and the multiple microphones forming a symmetrical structure.