Microphone Array Asymmetry for Sound Collection Stability
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Solution Overview
Problem
The existing microphone array configuration results in dispersed and uneven sound collection centers along the length direction, leading to unstable sound collection and adverse effects on directivity when a speaker is positioned between specific microphones, requiring large delays that negatively impact sound collection characteristics.
Innovation Solution
The microphone array is rearranged such that the sound collection centers of microphone units are concentrated around a central microphone, with microphones alternately positioned on opposite sides, and the distance between centrally disposed microphones and outer microphones is reduced, allowing for more efficient sound collection and downsizing of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microphones are arranged with increasing distances from a central point (D, D/2, D/4, D/8, D/16, D/32, D/64), then the microphone array can cover a wide frequency range with sharp directivity, but the sound collection centers become dispersed along the length direction, resulting in unstable sound collection
Solution Approach 1:
The patent applies asymmetry by reversing the conventional microphone arrangement pattern. Instead of placing microphones at distances D, D/2, D/4, D/8, D/16, D/32, D/64 from a central point (which creates dispersed sound collection centers), the invention arranges microphones at distances D, 2D, 4D, 8D, 16D, 32D, 64D from the central point. This asymmetric reversal concentrates the sound collection centers around the central microphone position, stabilizing sound collection while maintaining wide frequency range coverage and sharp directivity through beam forming processing.
2Productivity
If microphones are arranged to concentrate sound collection centers, then sound collection efficiency improves, but the length of the microphone array increases
Solution Approach 1:
The patent applies parameter changes by modifying the distance parameters between microphones and the central point. Instead of using decreasing distances (D, D/2, D/4, ...), the invention uses increasing distances (D, 2D, 4D, 8D, 16D, 32D, 64D). This parameter reversal achieves concentration of sound collection centers around the central microphone, improving sound collection efficiency. The geometric progression with factor 2 optimizes the balance between concentration and array length, allowing efficient sound collection while controlling the overall array dimensions.
3Ease of operation
If large delays are provided to control directivity orientation when a speaker is between specific microphones, then directivity orientation is controlled, but sound collection characteristics are adversely affected
Solution Approach 1:
The patent applies preliminary action by pre-configuring the microphone positions at specific distances (D, 2D, 4D, 8D, 16D, 32D, 64D) from the central microphone before operation. This preliminary arrangement ensures that sound collection centers are concentrated around the central position, creating an optimized baseline configuration. When a speaker is positioned between specific microphones, only minor delay adjustments are needed for directivity control, rather than requiring large delays that would adversely affect sound collection characteristics.
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
This configuration minimizes dispersion of sound collection centers, enhances sound collection efficiency, and maintains sharp directivity across a wide frequency range, while reducing the length of the microphone array and minimizing interference from reflected sounds.
Implementation Method 1
a first one of the microphone units includes three microphones arranged in line at regular intervals
Implementation Method 2
Audio signals from these microphones, which form microphone units, are processed by beam forming
Data Source
AI summary
A microphone array includes an n microphone units (where n is an integer equal to or larger than three). A first one of the microphone units includes three microphones ((14-1 through 14-3)) arranged in line at equal intervals. An m-th microphone unit (where m is a positive integer expressed by 1<m<n) includes the microphones at either end of an (m−1)-th microphone unit, and another microphone spaced from the microphone at one end of the (m−1)-th microphone unit by a distance substantially equal to the distance between the microphones at either end of the (m−1)-th microphone unit, and disposed at a location on the side of the (m−1)-th microphone unit opposite to the side where the microphone at the one end at the one end of the (m−1)-th microphone unit is disposed. The (m+1)-th microphone unit includes the microphones at either end of an m-th microphone unit, and another microphone spaced from the microphone at one end of the m-th microphone unit by a distance substantially equal to the distance between the microphones at either end of the m-th microphone unit, and disposed at a location on the side of the (m+1)-th microphone unit opposite to the side where the microphone at the one end of the (m+1)-th microphone unit is disposed.