Echo Canceller Dynamic Mixing Ratio Control
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Solution Overview
Problem
Conventional echo cancellers fail to completely remove echoes when the power ratio between front left and front right speakers changes dynamically, leading to incomplete cancellation of echoes and potential transmission of private information.
Innovation Solution
An echo canceller with adaptive filtering and dynamic mixing ratio adjustment, utilizing multiple mixers, adaptive filters, and subtractors to generate pseudo echo signals and adjust mixing ratios based on echo amounts in each microphone input, ensuring accurate echo removal across varying power ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed mixing ratio is used for combining speaker signals, then the device complexity is reduced, but the echo cancellation accuracy deteriorates when speaker power ratios change dynamically
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed mixing ratio to a dynamically adjustable mixing ratio that adapts to changing speaker power ratios. The mixing ratio changer modifies the mixing parameters in real-time based on detected echo amounts, allowing the system to maintain high echo cancellation accuracy across varying operating conditions while managing complexity through automated control.
Solution Approach 2:
The patent changes the mixing ratio parameter dynamically based on the power ratio between speakers. By adjusting this key parameter in response to changing conditions (speaker power ratios), the system maintains optimal echo cancellation performance without requiring complex manual configuration or fixed design assumptions.
2Measurement precision
If the mixing ratio is adjusted dynamically based on echo amounts, then the echo cancellation accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements feedback by using the detected echo amount as a control signal to adjust the mixing ratio. The echo amount detector continuously monitors residual echo levels, and the mixing ratio changer uses this feedback information to automatically optimize the mixing ratio, creating a closed-loop control system that improves accuracy without requiring complex manual intervention.
Solution Approach 2:
The system performs self-adjustment by automatically modifying its own mixing ratio based on real-time echo detection. The echo canceller autonomously optimizes its performance by using its own output (echo amount detection) to control its input (mixing ratio), eliminating the need for external manual adjustment or complex supervisory systems.
3Device complexity
If an identical reference signal is used for both FL and FR microphones, then the device complexity is reduced, but the echo removal completeness deteriorates when speaker outputs are asymmetric
Solution Approach 1:
The patent applies local quality by generating customized reference signals for each microphone based on its specific acoustic environment and the asymmetric speaker outputs. Instead of using a single identical reference signal for both microphones, the system tailors the reference signal characteristics to match the local conditions at each microphone, thereby improving echo removal completeness for asymmetric configurations.
Data Source
AI summary
Disclosed is an echo canceller 10 including: mixers 11A and 11B each to mix output signals outputted by speakers 7FL and 7FR with an instructed mixing ratio, and to generate reference signals for microphones 8A and 8B; an adaptive filter 12 to generate two pseudo echo signals from the two reference signals generated by the mixers 11A and 11B; subtractors 13A and 13B to subtract the two pseudo echo signals from input signals from the microphones 8A and 8B, and to generate two echo eliminated signals; residual echo detectors 14A and 14B to detect residual amounts of echo remaining in the echo eliminated signals obtained from the microphones 8A and 8B; and a mixing ratio changer 15 to instruct a change of the mixing ratios of the mixers 11A and 11B in accordance with the residual amounts of echo.