Echo Cancellation Device Acoustic Coupling Estimation

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Solution Overview

Problem

Conventional echo cancellation apparatuses face inaccuracies in estimating acoustic coupling amounts due to the inclusion of near-end speaker components in sound pickup signals, leading to incorrect echo power estimation and musical noise during double talk scenarios, and reliance on double talk detectors can create deadlocks.

Innovation Solution

An echo cancellation apparatus that calculates acoustic coupling amounts by adjusting the update amount based on the magnitude of components other than the echo component in the sound pickup signal, without using a double talk detector, through updated formulas and step size control to reduce the impact of near-end speaker components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional echo cancellation apparatus estimates acoustic coupling amount using cross spectrum sum value of reproduction signal and sound pickup signal, then echo power can be estimated, but near-end speaker components cause incorrect estimation and musical noise during double talk

Engineering Contradiction:

Improveacoustic coupling amount estimation accuracyVSAvoidecho power estimation reliability during double talk

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the sound pickup signal into echo components and near-end speaker components by analyzing spectral characteristics. The acoustic coupling amount estimation is performed separately for echo components only, excluding near-end speaker components that would otherwise contaminate the estimation and cause musical noise during double talk scenarios.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts and removes near-end speaker components from the sound pickup signal before performing acoustic coupling amount estimation. By taking out the harmful near-end speaker components that cause incorrect estimation, the system achieves accurate echo power estimation even during double talk without requiring double talk detection.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If double talk detector is used to detect near-end speaker components, then acoustic coupling amount estimation can be improved, but deadlock occurs between double talk detection and acoustic coupling amount estimation

Engineering Contradiction:

Improveacoustic coupling amount estimation accuracyVSAvoidsystem complexity with double talk detector

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements self-service by having the acoustic coupling amount estimation process automatically identify and exclude near-end speaker components through spectral analysis without requiring an external double talk detector. The estimation process itself serves to distinguish between echo and near-end speaker components, eliminating the need for separate detection mechanisms and avoiding deadlock situations.

Inventive Principle:

Principle #25Self-service

3Object-generated harmful factors

If echo cancellation is performed in frequency domain using STSA estimation, then echo suppression is achieved, but near-end speaker components remain and cause incorrect acoustic coupling amount estimation

Engineering Contradiction:

Improveecho suppression performanceVSAvoidacoustic coupling amount estimation accuracy

Core Design Contradiction:

Object-generated harmful factorsVSMeasurement precision

Solution Approach 1:

The patent applies local quality by performing frequency-selective processing where different handling is applied to different frequency components. In frequency bins where near-end speaker components are present, the acoustic coupling amount estimation is adjusted or excluded, while frequency bins containing only echo components are processed normally, achieving both echo suppression and accurate estimation.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12015902B2Echo cancellation device, echo cancellation method, and program

Publication Date: 2024.06.18 NIPPON TELEGRAPH & TELEPHONE CORP

AI summary

Provided is an echo cancellation apparatus capable of calculating an acoustic coupling amount with high accuracy regardless of the magnitude of the near-end speaker component and without using a double talk detector. The echo cancellation apparatus cancels an echo included in a sound pickup signal picked up by a microphone placed at a near-end and includes an acoustic coupling amount calculation unit that updates and calculates an acoustic coupling amount estimated value of a component of a reproduction signal, which is a signal picked up by a microphone placed at a far-end included in the sound pickup signal, such that an update amount is decreased the greater a magnitude of a component other than an echo component is in the sound pickup signal; a gain calculation unit that calculates a gain coefficient on the basis of the acoustic coupling amount estimated value; and an integration unit that integrates the gain coefficient with the sound pickup signal and generates an echo cancellation signal.