Wireless Microphone Echo Cancellation via Motion Detection
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Solution Overview
Problem
Audio conferencing systems face challenges in accurately distinguishing between far-end and near-end audio signals, especially when wireless microphones are in motion, leading to incorrect detection of double talk conditions and divergence of adaptive echo cancellation filters.
Innovation Solution
An electrically conductive element is integrated into the wireless microphone housing, connected to a touch-sensitive switch that generates a handling signal when the microphone is moved or handled, allowing the audio system to control the acoustic echo cancellation function and adapt filter coefficients accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adaptive filter continuously adapts to cancel acoustic echo, then echo cancellation effectiveness is improved, but the filter diverges when the wireless microphone is in motion
Solution Approach 1:
The system performs preliminary detection of microphone motion using motion sensors (accelerometer, gyroscope) before the adaptive filter processes audio signals. When motion is detected, the system proactively freezes filter coefficients in advance, preventing divergence before it occurs. This preliminary action allows the system to maintain reliable echo cancellation during stationary periods while avoiding filter divergence during motion.
Solution Approach 2:
The patent introduces motion detection signals from sensors as an intermediary between the physical state of the microphone and the adaptive filter processing. This intermediary signal serves as a reliable indicator that mediates between the need for continuous adaptation and the need to prevent divergence, enabling the system to make accurate decisions about when to freeze or update filter coefficients based on actual microphone motion rather than just audio signal analysis.
2Stability of the object's composition
If the system freezes filter coefficients to prevent divergence during motion, then filter stability is improved, but echo cancellation effectiveness deteriorates
Solution Approach 1:
The system dynamically adjusts filter coefficient update behavior based on real-time motion detection. Rather than statically freezing coefficients during all motion events, the system adaptively determines whether to update or freeze coefficients based on the magnitude and characteristics of detected motion. This dynamic approach allows the filter to maintain stability when motion is detected while continuing to adapt and maintain echo cancellation effectiveness when the microphone is stationary or stable.
3Measurement precision
If motion sensors are added to detect microphone handling, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent leverages motion sensors (accelerometer, gyroscope) that are already universally present in modern wireless microphones for other purposes such as orientation detection, handling detection, and user interaction recognition. By reusing these existing multi-functional sensors for echo cancellation control, the system achieves accurate motion detection without adding dedicated sensors, thereby improving detection accuracy while minimizing increases in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves the quality of both near-end and far-end audio signals by accurately differentiating between microphone movement and double talk, preventing divergence of the adaptive filter and maintaining effective echo cancellation.
Implementation Method 1
An electrically conductive element is integrated into the wireless microphone housing, connected to a touch-sensitive switch that generates a handling signal when the microphone is moved or handled
Data Source
AI summary
An audio system has a base station, a speaker and one or more wireless microphones. The audio system operates to receive audio information from both a far-end audio source and a near-end audio source and to process the audio information for transmission to a far-end audio system. The wireless microphones have an electrically conductive element connected to a touch sensitive switch, and the electrically conductive element is proximate to an outer perimeter surface of the microphones. When the outer perimeter surface of the microphone is touched, the switch is activated which sends a microphone handling signal to the base station. The base station uses the microphone handling signal to control an operational characteristic of an audio signal processing function running on the base station.