Acoustic Echo Cancellation Using Coherence-Based Reflection Damping
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Solution Overview
Problem
Existing sound cancellation systems require significant computational and memory resources, making them incompatible with lower-cost processors and challenging to adapt to changing environments, such as varying speaker positions and noise sources in vehicles.
Innovation Solution
A speech enhancement system that uses a coherence processor to identify similarities and differences between local and remote signals, issuing commands to a cancellation processor to dampen reflected sounds through time-varying gain elements or spectral subtraction, minimizing resource usage and adapting to changing environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional sound cancellation systems are used, then reflected sound can be suppressed, but computational and memory resources are excessively consumed
Solution Approach 1:
The sound cancellation system is segmented into distinct functional modules: a coherence processor that calculates coherence values between reference and error signals, and a cancellation processor that applies filtering based on coherence commands. This segmentation allows each module to perform specialized functions with optimized resource usage, avoiding the need for a single complex high-resource system.
Solution Approach 2:
A coherence processor acts as an intermediary between the reference signal and the cancellation processor. It calculates coherence values and generates coherence commands that guide the cancellation processor's filtering operations. This intermediary reduces the computational burden on the cancellation processor by pre-processing coherence information, thereby reducing overall computational and memory resource requirements.
2Object-affected harmful factors
If traditional sound cancellation systems are used, then reflected sound can be suppressed, but the system cannot adapt to changing environments such as varying speaker positions and noise sources
Solution Approach 1:
The system dynamically adapts to changing environments by continuously calculating coherence values between the reference signal and error signal. The coherence processor generates time-varying coherence commands that adjust the cancellation processor's filtering characteristics in real-time, enabling the system to adapt to varying speaker positions, posture changes, and different noise sources without requiring manual reconfiguration.
Solution Approach 2:
The system employs feedback through the coherence processor that continuously monitors the relationship between reference and error signals. Based on the calculated coherence values, the coherence processor adjusts the cancellation commands sent to the cancellation processor, creating a closed-loop system that automatically adapts to environmental changes such as speaker position shifts and changing acoustic conditions.
3Object-affected harmful factors
If high-resource sound cancellation systems are used, then reflected sound can be suppressed, but other features like navigation and voice recognition cannot operate simultaneously
Solution Approach 1:
The sound cancellation functionality is segmented into separate, optimized modules (coherence processor and cancellation processor) that can operate independently with minimal resource consumption. This segmentation frees up computational and memory resources that would otherwise be consumed by a monolithic sound cancellation system, enabling simultaneous operation of other features such as navigation and voice recognition.
Solution Approach 2:
The coherence processor serves as an efficient intermediary that pre-processes coherence information with minimal computational overhead. By handling coherence calculations separately, it reduces the real-time processing burden on the main system, allowing other resource-intensive features to operate simultaneously without interference.
Data Source
AI summary
A speech enhancement system improves the perceptual quality of an aural signal. A receiver detects and receives an unvoiced signal, a fully voiced signal, or a mixed voice remote signal. A coherence processor identifies the similarities or differences between a local signal and the remote signal. A cancellation processor or controller dampens reflected signals that may be part of the local signal.