Echo Cancellation via Frequency-Interval Distortion Measures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing echo cancellation technologies are suboptimal in addressing non-linear acoustic echoes due to the nonlinear characteristics of loudspeakers and amplifiers, leading to incomplete echo suppression and degradation of audio quality in communication systems.
Innovation Solution
An echo suppression system that generates distortion measures for specific frequency intervals, allowing for adaptive echo suppression by modifying the audio signal and residual signal in those intervals, reducing non-linear effects without requiring detailed non-linear models, and employing pre- and post-processing to optimize echo reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear echo cancellation is used, then the system complexity is low and implementation is simple, but the echo suppression is incomplete due to non-linear characteristics of loudspeakers and amplifiers
Solution Approach 1:
The patent segments the audio signal processing into multiple frequency intervals (e.g., low-frequency and high-frequency bands). For each frequency interval, separate distortion measures are generated and processed. This allows the system to handle non-linear echoes in different frequency ranges independently, improving overall echo suppression effectiveness while keeping each processing stage relatively simple.
Solution Approach 2:
The patent dynamically adjusts processing parameters based on the generated distortion measures. When non-linear distortion is detected in a specific frequency interval, the system modifies the audio signal parameters (such as gain adjustment or signal modification) for that interval. This adaptive parameter change enables effective non-linear echo suppression only where needed, rather than processing the entire signal uniformly.
2Measurement precision
If non-linear models are used to model loudspeaker behavior, then the echo cancellation accuracy improves, but the computational complexity and resource requirements increase significantly
Solution Approach 1:
The patent extracts only the essential non-linear distortion characteristics from the loudspeaker behavior by generating distortion measures for specific frequency intervals. Instead of using comprehensive non-linear models that capture all aspects of loudspeaker behavior, the system extracts and processes only the relevant distortion information needed for echo cancellation, significantly reducing computational complexity while maintaining accuracy.
Solution Approach 2:
The patent applies partial action by focusing echo suppression efforts only on frequency intervals where non-linear distortion is actually present (as indicated by distortion measures). Rather than applying complex non-linear processing to the entire audio spectrum, the system selectively processes only the portions of the signal that contain non-linear echo components, reducing overall computational burden.
3Ease of manufacture
If the loudspeaker is driven at high amplitude to ensure compact and low-cost implementation, then the device size and cost are reduced, but non-linear distortion increases
Solution Approach 1:
The patent converts the harmful non-linear distortion generated by high-amplitude loudspeaker operation into useful information through distortion measures. These measures identify the specific characteristics of the non-linear echoes, which are then used to generate appropriate compensation signals. The system transforms the problem of non-linear distortion into an opportunity for targeted echo cancellation, allowing high-amplitude operation without sacrificing audio quality.
Data Source
AI summary
An audio echo suppressor includes a first receiver for receiving a first audio signal for rendering by a loud-speaker and a second receiver for receiving a microphone signal. A linear echo-cancellation filter generates a first compensation signal from the first audio signal and a compensator generates a residual signal by compensating the microphone signal for the first compensation signal. A first adapter determines filter parameters for the linear echo-cancellation filter. An estimator generates distortion measures where each distortion measure is indicative of the contribution to the residual signal in a frequency interval outside a first frequency interval. The residual signal results from rendering of signal components of the first audio signal that are within the first frequency interval. An echo reducer performs echo suppression based on the distortion measures.