Sound Field Stabilizer Using Spectral Coherence Compensation
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Solution Overview
Problem
Existing sound field processing systems using multiple microphones often lose spatial information due to noise suppression processes, resulting in a mono output signal with no spatial information, which affects the quality and accuracy of sound reproduction.
Innovation Solution
A system and method that calculate balance gains for multiple microphone signals to maintain spatial stability, incorporating noise reduction and echo cancellation processes, while using structured noise detection and spectral coherence to adjust signal gains and prevent unnecessary attenuation of high-frequency signals, thereby preserving the spatial image of the sound field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise suppression processes are applied to multiple microphone signals, then noise performance is improved, but spatial information is lost resulting in mono output signal
Solution Approach 1:
The noise suppression is applied separately to different frequency bands rather than uniformly across all frequencies. High-frequency signals are processed with different gain adjustments compared to low-frequency signals, allowing spatial information to be preserved in certain bands while noise suppression is applied in others.
Solution Approach 2:
Different processing strategies are applied to different parts of the signal spectrum. The system applies spectral coherence compensation specifically to high-frequency signals where spatial information is critical, while applying different noise suppression techniques to lower frequencies where spatial cues are less important.
2Object-generated harmful factors
If signal gains are adjusted for noise reduction and echo cancellation, then noise and echo are reduced, but high-frequency signals may be unnecessarily attenuated
Solution Approach 1:
The system calculates spectral coherence between microphone signals and uses this feedback to adjust gain adjustments. When spectral coherence indicates that high-frequency signals contain meaningful spatial information, the system compensates by applying less attenuation or even boosting these frequencies to maintain signal fidelity.
Solution Approach 2:
The system dynamically changes the gain parameter for high-frequency signals based on calculated spectral coherence values. Instead of applying fixed noise reduction gains across all frequencies, the system adjusts the frequency-dependent gain parameter to preserve or enhance high-frequency content when spatial information is present.
3Stability of the object's composition
If balance gains are calculated and applied to multiple microphone signals, then spatial stability is improved, but system complexity increases
Solution Approach 1:
The system applies spectral coherence compensation selectively to specific frequency ranges (particularly high frequencies) rather than processing the entire signal spectrum uniformly. This partial action approach maintains spatial stability where it matters most while reducing the overall computational complexity compared to full-spectrum processing.
Data Source
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AI summary
In a system and method for maintaining the spatial stability of a sound field a balance gain may be calculated for two or more microphone signals. The balance gain may be associated with a spatial image in the sound field. Signal values may be calculated for each of the microphone. The signal values may be signal estimates or signal gains calculated to improve a characteristic of the microphone signals. The differences between the signal values associated with each microphone signal may be limited although some difference between signal values may be allowable. One or more microphone signals are adjusted responsive to the two or more balance gains and the signal gains to maintain the spatial stability of the sound field. The adjustments of one or more microphone signals may include mixing of two or more microphone. The signal gains are applied to the two or more microphone signals.