Echo Canceller Using Smoothed Speech Signals for Real-Time Delay Adaptation
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Solution Overview
Problem
Existing echo cancellers in personal computers face challenges in effectively canceling acoustic echoes due to sudden changes in echo path delay characteristics, often requiring hardware alterations or external devices, which compromise ease of use and accuracy.
Innovation Solution
An echo canceller that includes a pseudo echo generation mechanism using an adaptive filter, smoothing algorithms for speech signals, and a delay time information generation system to update tap coefficients in real-time, allowing for effective echo cancellation without external hardware modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware configuration changes are made to route reference signal lines through buffers on both sending and receiving sides, then echo cancellation accuracy is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent replaces the mechanical hardware configuration (jumper connections, buffer routing) with a software-based solution. The echo canceller uses signal processing algorithms to achieve echo cancellation without requiring physical modifications to the sound device hardware, thereby maintaining ease of operation while improving accuracy.
Solution Approach 2:
The patent introduces an intermediary software layer (the echo canceller application) that operates between the microphone input and the output processing. This software intermediary processes the audio signals to cancel echo effects without requiring changes to the underlying hardware configuration, thus avoiding the complexity of hardware modifications.
2Measurement precision
If hardware modifications are made to establish short circuits between stereo output and input terminals, then echo path delay characteristics are improved, but ease of operation and functional characteristics of general-purpose PC deteriorate
Solution Approach 1:
The patent replaces mechanical hardware modifications (short circuits, jumper connections) with a software-based echo cancellation system. The solution processes audio signals digitally to compensate for echo path characteristics without requiring any physical alterations to the PC's sound device, thereby preserving ease of operation and the general-purpose functionality of the PC.
3Productivity
If time-sharing processing with other software is implemented, then system resource utilization is improved, but audio signal processing continuity deteriorates causing echo path characteristic changes
Solution Approach 1:
The patent implements a dynamic echo cancellation system that continuously adapts to changing echo path characteristics. The adaptive filter updates its coefficients in real-time to track variations caused by time-sharing processing, allowing the system to maintain effective echo cancellation despite interruptions and delays in audio signal processing caused by other software operations.
Data Source
AI summary
An echo canceller which can respond to a sudden change in echo characteristics in real time and does not require an alteration outside the echo canceller, includes a smoothed sending-speech signal calculation means for calculating a smoothed sending-speech signal from the sending-speech signal, the smoothed sending-speech signal being obtained by smoothing the sending-speech signal; a smoothed receiving-speech signal calculation means for calculating a smoothed receiving-speech signal from the receiving-speech signal, the smoothed receiving-speech signal being obtained by smoothing the receiving-speech signal; a delay time information generation means for obtaining delay time information reflecting delay characteristics of an echo path in accordance with a correlation between the smoothed sending-speech signal and the smoothed receiving-speech signal; and an update information generation means for obtaining update information indicating execution or suspension of updating of the tap coefficients of the adaptive filter, in accordance with the sending-speech signal, the receiving-speech signal, and the delay time information.