Echo Cancellation Using Push-to-Talk State Detection

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Solution Overview

Problem

Conferencing systems face challenges with echo cancellation, particularly when using push-to-talk microphones, as the system lacks a definitive status signal for mute functions, leading to incoherence in echo canceller coefficients and divergence during unrecognized microphone turn-off or turn-on events, resulting in echo and feedback issues.

Innovation Solution

Implementing an acoustic echo cancellation system with converging coefficients and a detector for turn-off and turn-on events of push-to-talk microphones, utilizing a high-pass filter, transient detector, or adjustable high-pass filter to disable the echo canceller when a push-to-talk microphone is turned off, and employing a push-to-talk detector to mitigate coefficient divergence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If echo cancellation is implemented in conferencing systems, then echo and feedback are reduced, but coefficient divergence occurs during unrecognized microphone turn-off or turn-on events

Engineering Contradiction:

Improveecho and feedbackVSAvoidcoefficient stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system performs preliminary detection of microphone states using push-to-talk detectors before echo cancellation processing. By detecting turn-off and turn-on events in advance through high-pass filters and transient detectors, the system can prepare appropriate coefficient adjustments, preventing divergence before it occurs during echo cancellation operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the detected microphone state information is fed back to adjust echo canceller coefficients dynamically. When push-to-talk detectors identify microphone turn-off or turn-on events, the system responds by adjusting coefficients accordingly, creating a closed-loop control system that maintains coefficient stability while continuing to cancel echo effectively.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If push-to-talk microphones are used to enable participant control, then ease of operation is improved, but the system lacks definitive status signals leading to coefficient incoherence

Engineering Contradiction:

Improveparticipant controlVSAvoidmicrophone status signal

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The system introduces push-to-talk detectors as intermediary devices that monitor microphone states. These detectors use high-pass filters and transient detectors to sense microphone turn-off and turn-on events, acting as mediators that translate physical microphone states into detectable electrical signals. This intermediary layer recovers the lost status information without requiring changes to the push-to-talk microphone hardware itself.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces the need for mechanical or electrical status signals from push-to-talk microphones with an electronic detection mechanism. By using high-pass filters and transient detectors to sense microphone state changes electrically, the system substitutes a sophisticated electronic sensing approach for the missing status signal, maintaining full functionality without requiring modifications to the original microphone design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Duration of action of stationary object

If the echo canceller remains active during microphone turn-off events, then echo cancellation continues, but coefficient divergence occurs due to unrecognized events

Engineering Contradiction:

Improveecho cancellation continuityVSAvoidcoefficient convergence

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The system dynamically adjusts echo canceller operation based on real-time microphone state detection. When push-to-talk detectors identify microphone turn-off events, the system dynamically modifies coefficient updates or disables the echo canceller temporarily. This dynamic adaptation allows the system to maintain coefficient convergence during microphone state changes while restoring continuous echo cancellation functionality when microphones are active, resolving the contradiction between continuity and reliability.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8199927B1Conferencing system implementing echo cancellation and push-to-talk microphone detection using two-stage frequency filter

Publication Date: 2012.06.12 BIAMP SYST LLC

AI summary

Disclosed herein are conferencing products implementing an acoustic echo cancellation system that utilizes converging coefficients and a detector of turn-off and/or turn-on events of push-to-talk microphones, and, further, that mitigates against divergence and/or drift of coefficients and other variables of an echo canceller. A push-to-talk detector may be used that includes a high-pass filter, a transient detector, or an adjustable high-pass filter. An echo canceller may be disabled as to a push-to-talk microphone that has been turned off.