Adaptive Directional Microphone Interference Suppression
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Solution Overview
Problem
Existing directional microphones face challenges in simultaneously optimizing the suppression of interference powers and microphone noise, particularly for second-order directional microphones, where increasing directional effect leads to increased microphone noise, and there is no common method to balance signal and noise sources from undesired directions.
Innovation Solution
The method employs adaptive filtering of at least two microphone signals using FIR filters, allowing optimization of adaptation parameters to minimize interference powers by defining angle ranges for interference sources while maintaining signal integrity from the desired direction, reducing overall output signal power and microphone noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the directional effect of a directional microphone is increased, then the suppression of interference signals from undesired directions is improved, but the microphone noise increases
Solution Approach 1:
The patent divides the interference reduction task into multiple frequency bands using a filter bank. Each bandpass filter processes specific frequency ranges independently, allowing selective optimization of directional effect and noise suppression for different frequencies. This segmentation enables the system to reduce overall interference without uniformly increasing microphone noise across all frequencies.
Solution Approach 2:
The patent dynamically adjusts adaptation parameters of the filter bank based on the spectral distribution of interference sources. By changing filter coefficients and adaptation parameters according to the frequency content of interfering signals, the system optimizes the balance between directional suppression and microphone noise reduction for varying acoustic environments.
2Object-affected harmful factors
If adaptive filtering is applied to achieve directional effect, then interference suppression is improved, but the device complexity increases
Solution Approach 1:
The filter bank serves multiple functions simultaneously: it performs frequency decomposition, directional beamforming, and adaptive interference suppression. By making the filtering system multi-functional, the patent reduces the need for separate dedicated components for each function, thereby managing device complexity while achieving effective interference suppression.
Solution Approach 2:
The adaptive filter automatically adjusts its parameters based on the input signal characteristics and interference patterns. The system performs self-optimization without requiring manual configuration or external control, reducing the complexity of system management and adaptation while maintaining effective interference suppression.
Data Source
AI summary
The interference powers with directional microphones are to be suppressed as far as possible. To this end, provision is made to adaptively filter the microphone of a number of microphones as a function of at least one parameter. The directional effect of the directional microphone achieved in this way is adjusted by modifying the at least one parameter, such that the summation of interference powers including microphone noises is reduced and/or minimal.