Portable Speakerphone False Doubletalk Detection
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Solution Overview
Problem
Existing teleconferencing systems face challenges in maintaining effective echo cancellation, especially in dynamic environments with frequent changes in echo paths, leading to poor audio quality and unreliable doubletalk detection, which affects the adaptation of echo cancellation coefficients.
Innovation Solution
The implementation of a doubletalk detector in a low frequency range, combined with a secondary confirmatory detector and accelerated coefficient adaptation, allows for improved echo cancellation by distinguishing between far-end and near-end audio, and adapting coefficients even during half-duplex operation to maintain audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional doubletalk detection is used in teleconferencing systems, then the system can detect near-end and far-end speech, but the detection becomes unreliable in dynamic environments with frequent echo path changes
Solution Approach 1:
The patent divides the audio frequency spectrum into multiple frequency bands and implements separate doubletalk detectors for each band. This segmentation allows the system to detect doubletalk conditions more reliably by analyzing specific frequency ranges independently, reducing the impact of echo path changes in other bands on overall detection accuracy.
Solution Approach 2:
The system dynamically adapts to echo path changes by continuously monitoring multiple frequency bands and adjusting detection parameters in real-time. When changes are detected in certain bands, the system can weight or prioritize other bands that remain stable, maintaining reliable doubletalk detection despite dynamic environmental conditions.
2Reliability
If echo cancellation coefficients are adapted during doubletalk, then the system can maintain audio quality, but the presence of near-end speech interferes with accurate echo cancellation
Solution Approach 1:
The patent segments the audio signal into multiple frequency bands and applies echo cancellation independently to each band. This allows the system to adapt coefficients for each band separately, reducing the interference from near-end speech in other bands and maintaining better overall audio quality during doubletalk conditions.
Solution Approach 2:
The system applies different echo cancellation parameters and adaptation rates to different frequency bands based on local conditions in each band. This local quality approach allows optimal echo cancellation in bands where far-end speech is dominant while tolerating some interference in bands where near-end speech is present.
3Ease of operation
If the system operates in full-duplex mode, then both parties can speak simultaneously, but echo cancellation becomes less effective during doubletalk events
Solution Approach 1:
The system dynamically adjusts echo cancellation parameters based on real-time detection of doubletalk conditions in different frequency bands. During full-duplex operation, when doubletalk is detected in certain bands, the system automatically reduces adaptation in those bands while maintaining full-duplex functionality, preserving both ease of operation and echo cancellation effectiveness.
Data Source
AI summary
Disclosed herein are portable teleconferencing products that implement a doubletalk detector in a low frequency range or in a frequency range commensurate with the frequencies through which sound may be efficiently transferred between a speaker and a microphone through an enclosure. Also disclosed herein are teleconferencing systems that implement a secondary doubletalk detector, a non-presumptive doubletalk detector, a confirmatory doubletalk detector, and/or a false doubletalk detector, whereby echo cancellation coefficients may be better adapted after echo path changing events through the use of accelerated coefficient adaptation or half-duplex operation until adaptation is restored. Further disclosed herein are teleconferencing products that include more than one port for communicating with distant parties or a single party and a local source of audio material, whereby one distant party is prevented from being transmitted to it private audio from another party or another audio signal while permitting a local participant to hear the private audio. Detailed information on various example embodiments of the inventions are provided in the Detailed Description below, and the inventions are defined by the appended claims.