Microphone Phase Response Adjustment via Segmented Filter Optimization
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Solution Overview
Problem
In microphone systems, especially in hearing aids and communication devices, the phase responses of microphones can differ due to manufacturing tolerances and aging, which affects the performance of differential beamforming and requires adjustment to achieve equal phase responses across microphones.
Innovation Solution
A method involving the determination of two filters with adaptation parameters to compensate for the differences in phase responses, where a global filter is constructed from these filters through multidimensional optimization, allowing for the adjustment of phase responses by applying the filters to the microphone signals with optimized parameter values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two separate filters are used to compensate for electroacoustic and electronic component influences independently, then the phase response adjustment can be more precise, but the device complexity and parameter optimization difficulty increase
Solution Approach 1:
The compensation filter is divided into two separate filters: a first filter for compensating electroacoustic component influences and a second filter for compensating electronic component influences. Each filter targets specific frequency ranges (approx. 60 Hz for electroacoustic, approx. 120 Hz for electronic) with distinct adaptation parameters, enabling independent optimization of each compensation function while maintaining overall phase response accuracy.
2Measurement precision
If adaptive filters with multiple parameters are used to compensate for phase differences, then the phase response can be better adjusted, but the convergence speed and optimization stability deteriorate
Solution Approach 1:
The adaptation process is segmented into two independent parallel processes: one for optimizing the first adaptation parameter of the first filter and another for optimizing the second adaptation parameter of the second filter. This segmentation reduces the dimensionality of the optimization problem from multiple parameters to two separate single-parameter optimizations, significantly improving convergence speed and stability while achieving the same phase response matching accuracy.
Data Source
AI summary
The phase responses of a first and a second microphone are adjusted with first and second filters that filter their microphone signals. The first filter corresponds to a first contribution to a phase shift between the microphones and includes a first adaptation parameter. The second filter corresponds to a second contribution to the phase shift and has a second adaptation parameter. A global filter, which is formed with the first and second filters, represents the first and second contributions to the phase shift and includes the first and second adaptation parameters. The global filter determines a first value for the first adaptation parameter and a second value for the second adaptation parameter via a multidimensional optimization. The phase responses are adjusted by applying the first filter and the second filter to at least one of the microphone signals with the adaptation parameters set to the first and second values, respectively.