Personal Speakerphone Dual Doubletalk Detection Echo Cancellation
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Solution Overview
Problem
Existing speakerphone devices face challenges in maintaining effective echo cancellation, especially in dynamic environments, due to changes in echo paths and the inability to reliably detect doubletalk, leading to degraded audio quality and coefficient incoherence.
Innovation Solution
A personal speakerphone device with a controller, frequency band decomposers, echo cancellers, and dual doubletalk detectors that adapt coefficients based on low-frequency and high-frequency audio analysis, using a primary detector for initial adaptation and a secondary detector for confirmation and false doubletalk detection, ensuring reliable echo cancellation and coefficient coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single doubletalk detector is used in existing speakerphone devices, then the device structure remains simple, but the reliability of doubletalk detection degrades in dynamic environments with changing echo paths
Solution Approach 1:
The detection system is divided into two independent doubletalk detectors: a first doubletalk detector that operates under normal conditions and a second doubletalk detector that operates when echo path changes are detected. Each detector is responsible for specific detection scenarios, improving overall reliability without requiring complete system redesign.
Solution Approach 2:
The system dynamically switches between the first and second doubletalk detectors based on echo path stability. When an echo path change is detected, the system transitions from using the first detector to using the second detector, allowing the detection mechanism to adapt to changing environmental conditions.
2Adaptability or versatility
If echo cancellation coefficients are continuously adapted, then the system responds quickly to echo path changes, but coefficient incoherence occurs during doubletalk periods degrading audio quality
Solution Approach 1:
The system uses feedback from the doubletalk detection mechanism to control coefficient adaptation. When doubletalk is detected by either the first or second doubletalk detector, the system prevents coefficient adaptation, avoiding the introduction of incoherent coefficients that would degrade audio quality. When single-talk conditions are detected, adaptation proceeds normally to track echo path changes.
3Device complexity
If the system uses traditional doubletalk detection methods, then the implementation remains simple, but false doubletalk detection occurs leading to premature adaptation cessation
Solution Approach 1:
The second doubletalk detector acts as an intermediary verification mechanism. Before the system accepts a doubletalk condition and stops adaptation, the second detector verifies the detection by the first detector. This intermediate verification step prevents false doubletalk detection from causing premature adaptation cessation, while adding only moderate complexity to the system.
Data Source
AI summary
This disclosure describes a personal speakerphone device for teleconferencing a local participant with near side audio data and a far side participant with far side audio data. The device includes a controller that couples to a speaker and a microphone inside an enclosure that couples the speaker and the microphone within a coupling frequency range, and where the enclosure houses the speaker, the microphone, the controller, analog to digital conversion circuitry, digital to analog conversion circuitry, supporting circuitry, and one or more ports for data through which audio data is transferred. Additionally, the device includes a first frequency band decomposer, a second frequency band decomposer, one or more echo cancellers, and a converger. Further, the device includes a primary doubletalk detector and a secondary doubletalk detector.