Directional Microphone Low Band Phase Correction
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Solution Overview
Problem
Existing directional microphone apparatuses face challenges in correcting both level and phase differences between non-directional microphone units, particularly in the low band, leading to inadequate directivity and amplitude frequency characteristic issues, especially due to air leakage and manufacturing variations.
Innovation Solution
A directional microphone apparatus with a configuration that includes a correction process section to correct signals using calculated correction parameters, a directivity synthesis section for synthesizing directivity, and a level difference calculation section to calculate and update these parameters, simultaneously addressing level and phase differences between non-directional microphone units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only level difference correction is performed between microphone units, then level balance is improved, but phase difference remains uncorrected causing directivity deterioration in low band
Solution Approach 1:
The invention changes the correction parameters from simple level adjustment to complex parameters that include both level and phase information. By using frequency-dependent correction parameters that account for both amplitude and phase characteristics, the system simultaneously corrects both level difference and phase difference, resolving the contradiction between level balance improvement and directivity maintenance.
2Volume of moving object
If microphone units are arranged in small scale, then device size is reduced, but directivity formation capability deteriorates
Solution Approach 1:
The invention applies digital signal processing with frequency-dependent correction parameters to compensate for the reduced spatial separation. By adjusting the correction parameters based on the actual level and phase characteristics of each microphone unit, the system can achieve effective directivity formation even when physical microphone spacing is limited, thus resolving the contradiction between compact size and directivity capability.
3Productivity
If manufacturing inspection is performed to guarantee quality, then production yield is improved, but individual differences in level and phase difference still remain
Solution Approach 1:
The invention implements a feedback mechanism where the actual level and phase characteristics of each microphone unit are measured and used to generate individualized correction parameters. This feedback loop compensates for manufacturing variations that persist even after quality inspection, allowing the system to adapt to individual unit characteristics and maintain signal consistency across all microphone units.
4Ease of manufacture
If air leakage is prevented in manufacturing, then manufacturing complexity increases, but level and phase differences in low band are reduced
Solution Approach 1:
The invention replaces mechanical prevention of air leakage with a digital signal processing solution. Instead of increasing manufacturing complexity to eliminate air leakage paths, the system uses electronic correction parameters to compensate for the acoustic effects of air leakage, thereby maintaining low band signal quality without additional manufacturing steps.
Data Source
AI summary
A directional microphone apparatus and directivity control method that corrects a level difference and a phase difference generated in a low band in a plurality of non-directional microphone units, improve the directivity, and reduce the size are provided. Level difference calculation section (105) calculates the level difference between first signal x1(t) obtained by first non-directional microphone unit (101) and second signal x2(t) obtained by second non-directional microphone unit (102), and correction parameter calculation section (106) calculates coefficients of a linear IIR filter configuring correction process section (103) based on the level difference. Correction process section (103) simultaneously corrects the level difference and a phase difference in the low band between two non-directional microphone units by using the calculated coefficients.