Echo Suppressor Using Past Path Characteristics for Noise Buried Bins
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Solution Overview
Problem
Existing echo suppressors fail to effectively suppress acoustic echo signals due to erroneous calculation of echo path characteristics, especially when frequency components of small frequency bins in far-end signals are buried in background noise, leading to inappropriate suppression performance.
Innovation Solution
The proposed echo suppressor uses past estimated echo path characteristics for frequency bins with small frequency components, preventing erroneous learning and maintaining echo-suppressing performance by determining the presence of frequency components and updating echo path characteristics only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If echo path characteristics are calculated using far-end and near-end input signals for all frequency bins, then echo suppression is attempted across the full spectrum, but erroneous echo path characteristics are obtained for frequency bins with small components buried in background noise, leading to poor echo suppression performance
Solution Approach 1:
The patent applies local quality by treating different frequency bins differently based on their characteristics. For frequency bins with small frequency components that are buried in background noise, the patent uses past estimated echo path characteristics instead of calculating new ones. This localized differentiation prevents erroneous updates in problematic frequency regions while maintaining accurate echo suppression in valid regions.
Solution Approach 2:
The patent implements preliminary action by using past estimated echo path characteristics as a fallback before erroneous calculations can occur. When frequency components are detected to be buried in background noise, the system retrieves and uses previously estimated echo path characteristics, preventing the system from learning incorrect patterns and maintaining stable performance.
2Adaptability or versatility
If echo path characteristics are continuously updated using current far-end and near-end signals, then the system adapts to changing acoustic environments, but small frequency components buried in background noise cause erroneous updates that degrade echo suppression performance
Solution Approach 1:
The patent implements feedback by detecting the presence of valid frequency components before updating echo path characteristics. The frequency bin component detector provides feedback about the quality of frequency components, and this feedback controls whether updates should proceed. When feedback indicates that components are buried in background noise, the system suppresses updates, maintaining stable performance.
Solution Approach 2:
The patent applies preliminary action by performing a preliminary detection of frequency component validity before executing the update operation. This preliminary check prevents erroneous updates from occurring in the first place, ensuring that only valid echo path characteristics are updated while maintaining stability in problematic conditions.
Data Source
AI summary
In an echo suppressor, a frequency bin component detector compares a far-end signal amplitude spectrum with a threshold value for each frequency bin to determine whether or not each frequency bin includes a frequency component. A frequency bin echo path characteristic estimator uses the far-end signal amplitude spectrum in the frequency bins determined to have a frequency component by the frequency bin component detector and the near-end input signal amplitude spectrum of corresponding frequency bins to estimate the echo path characteristics of the frequency bins. An estimated echo signal calculation-and-echo suppressor section calculates estimated echo signals based on the echo path characteristic in each frequency bin and the far-end signal amplitude spectrum to suppress the estimated echo signals from the near-end input signal amplitude spectrum.