Real-Time Acoustic Feedback Suppression via Adaptive Equalization
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Solution Overview
Problem
Acoustic feedback, particularly howling, occurs in communication systems due to high system gain, which existing solutions fail to address effectively, especially in real-time and across both speech activity and inactivity intervals, leading to suboptimal perceptual quality and increased computational complexity.
Innovation Solution
The system generates and updates an estimated system gain spectrum in real-time, tracks peak gains, and applies adaptive equalization filters to reduce the level of speech signals at peak frequencies, ensuring robustness against howling without flattening the gain spectrum, thus maintaining audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing acoustic feedback reduction methods are applied, then acoustic feedback is reduced, but computational complexity increases and real-time performance is compromised
Solution Approach 1:
The patent segments the acoustic feedback reduction process into distinct functional modules: system gain spectrum estimation, peak gain tracking, and adaptive equalization filter application. Each module operates independently with specific parameters, allowing efficient real-time processing without excessive computational complexity.
Solution Approach 2:
The patent dynamically changes parameters of the equalization filter based on tracked peak gains in the system gain spectrum. By adjusting filter coefficients in real-time according to measured acoustic characteristics, the system effectively reduces feedback while maintaining computational efficiency through parameter adaptation rather than complex structural changes.
2Object-affected harmful factors
If aggressive noise attenuation is applied to reduce acoustic feedback, then feedback reduction improves, but audio quality deteriorates
Solution Approach 1:
The patent applies local quality by targeting specific frequency regions where acoustic feedback occurs. Instead of uniformly attenuating all frequencies, the system identifies peak gain frequencies in the system gain spectrum and applies equalization filters only at those specific frequency locations, thereby reducing feedback while preserving audio quality in other frequency bands.
3Object-affected harmful factors
If the system gain spectrum is flattened to eliminate feedback, then acoustic feedback is reduced, but perceptual quality of audio signals deteriorates
Solution Approach 1:
The patent implements local quality by applying selective equalization only at peak gain frequencies rather than flattening the entire system gain spectrum. This localized approach reduces acoustic feedback at problematic frequencies while maintaining the natural spectral characteristics and perceptual quality of the audio signal across other frequency ranges.
4Device complexity
If equalization filters are applied only during speech activity, then computational complexity is reduced, but acoustic feedback reduction effectiveness deteriorates
Solution Approach 1:
The patent applies equalization filters continuously during both speech activity and speech inactivity intervals. This continuous application ensures that acoustic feedback is reduced at all times, including during non-speech periods when feedback can still occur, thereby maintaining effectiveness without requiring excessive computational complexity through intermittent processing.
Data Source
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AI summary
An estimated system gain spectrum of an acoustic system is generated, and updated in real-time to respond to changes in the acoustic system. Peak gains in the estimated system gain spectrum are tracked as the estimated system gain spectrum is updated. Based on the tracking, at least one frequency at which the estimated system gain spectrum is currently exhibiting a peak gain is identified. Based on the identification of the at least one frequency, an audio equalizer is controlled to apply, to a first speech containing signal to be played out via an audio output device of the audio device and/or to a second speech containing signal received via an audio input device of the audio device, an equalization filter to reduce the level of that signal at the identified frequency. The equalization filter is applied continuously throughout intervals of both speech activity and speech inactivity in that signal.