Residual Echo Suppression for Motile Audio Devices Under Doppler Shift
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Solution Overview
Problem
Existing acoustic echo cancellation techniques in mobile devices are less than optimal due to Doppler shifts caused by motion, leading to residual echo suppression challenges, especially when the device moves and changes its perspective of the environment.
Innovation Solution
An autonomously motile device employs adaptive filters and algorithms like least-mean-squares to estimate and suppress residual errors, accounting for Doppler shifts by warping the magnitude spectrum of microphone data and updating filter coefficients based on velocity, and uses beamforming to isolate desired audio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic echo cancellation is used in mobile devices, then echo suppression is achieved, but residual echo errors occur due to Doppler shifts caused by motion
Solution Approach 1:
The system dynamically adapts filter coefficients based on real-time velocity data from motion sensors. The adaptive filter continuously updates its parameters to track changing acoustic conditions caused by device motion, transforming a static echo cancellation system into a dynamic one that can compensate for Doppler shifts and maintain accuracy during movement.
Solution Approach 2:
The system changes the parameters of the adaptive filter based on velocity information. By adjusting filter coefficients according to measured motion parameters, the system compensates for Doppler-induced frequency shifts and maintains accurate echo cancellation despite device movement through parameter adaptation.
2Adaptability or versatility
If the device moves to interact with users, then user interaction capability is improved, but Doppler shifts cause residual echo errors
Solution Approach 1:
The system uses feedback from motion sensors to continuously monitor device velocity and adjusts the adaptive filter coefficients accordingly. This closed-loop feedback mechanism ensures that the echo cancellation system remains synchronized with the actual acoustic conditions, preventing information loss despite device movement and maintaining audio data accuracy.
Solution Approach 2:
The system performs preliminary compensation for Doppler shifts by using velocity data to pre-adjust filter parameters before processing audio signals. This anticipatory adjustment prevents residual echo errors from occurring in the first place, maintaining audio accuracy proactively rather than reactively.
3Measurement precision
If adaptive filters are updated based on velocity data, then residual echo suppression is improved, but computational complexity increases
Solution Approach 1:
The system applies partial updates to filter coefficients based on velocity magnitude, adjusting computational effort to match the actual motion conditions. When device motion is minimal, full adaptive updates are unnecessary, so the system reduces computational activity while maintaining sufficient echo suppression accuracy, avoiding excessive processing during low-motion periods.
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
Effectively reduces or eliminates residual echo errors caused by motion and Doppler shifts, improving audio processing accuracy and user interaction in dynamic environments.
Implementation Method 1
When the autonomously mobile device moves, it may receive audio reflections from nearby reflective surfaces. Because the device is moving, however, these reflections may be affected by Doppler shifts.
Data Source
AI summary
A device capable of autonomous motion includes a residual echo suppressor for suppressing echoes caused by an output reference signal. When the device outputs audio while moving with a velocity, it may receive echoes that are Doppler-shifted due to the motion. The residual echo suppressor generates estimated residual error data based on phase-shifted reference data to account for and suppress the Doppler-shifted echoes.