Echo Suppression via Dynamic Filter Control
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Solution Overview
Problem
Existing communication devices face challenges in effectively minimizing echo and feedback in telecommunication systems, particularly in systems with geographically separated handsets, where acoustic and electric feedback loops can lead to echo issues that affect sound quality.
Innovation Solution
A communication device with dynamically controlled microphone and loudspeaker signal paths, utilizing configurable filters that operate in complementary modes to selectively pass or attenuate frequency bands, ensuring echo suppression while maintaining acceptable sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complementary comb filters are used to minimize echo, then echo suppression is improved, but sound quality and speech intelligibility deteriorate
Solution Approach 1:
The frequency spectrum is divided into multiple sub-bands using a filter bank, allowing independent processing of each sub-band. This segmentation enables selective echo suppression in specific frequency ranges while preserving other frequencies, thereby reducing the overall harmful echo effect without completely degrading sound quality.
Solution Approach 2:
Different filter characteristics are applied to different sub-bands based on their specific properties. The system adapts the filtering strength and type for each sub-band, applying stronger echo suppression where needed and weaker or no filtering where sound quality preservation is more important, achieving local optimization of both echo reduction and audio quality.
2Object-affected harmful factors
If echo suppression is enhanced, then echo reduction is improved, but speech intelligibility deteriorates
Solution Approach 1:
The system dynamically adjusts filter coefficients and processing parameters in real-time based on the detected acoustic environment and speech characteristics. This dynamic adaptation allows the system to strengthen echo suppression when echoes are prominent while weakening it when speech clarity is more critical, maintaining speech intelligibility throughout the conversation.
Solution Approach 2:
The system changes processing parameters such as filter coefficients, gain factors, and threshold values based on detected conditions. By continuously monitoring the acoustic scene and adjusting parameters accordingly, the system optimizes the balance between echo reduction and speech intelligibility, preventing information loss while minimizing harmful echo effects.
3Device complexity
If fixed filter characteristics are used, then system complexity is reduced, but adaptability to different acoustic environments deteriorates
Solution Approach 1:
The system performs preliminary analysis of the acoustic environment and speech characteristics before applying filter processing. By detecting the current acoustic scene in advance and preparing appropriate filter settings, the system can quickly adapt to different environments without requiring complex real-time computation, reducing overall system complexity while maintaining adaptability.
Solution Approach 2:
The system continuously monitors the acoustic environment and speech signals, using this feedback to automatically adjust filter characteristics. This feedback mechanism enables the system to adapt to changing acoustic conditions without requiring manual intervention or complex reconfiguration, achieving environmental adaptability through simple and efficient automatic parameter adjustment.
Data Source
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AI summary
The application relates to a communication device, e.g. a speakerphone, comprising a microphone signal path, termed MSP, and a loudspeaker signal path, termed SSP, the microphone signal path comprising a microphone unit, an MSP-signal processing unit comprising an MSP-filter, and a transmitter unit operationally connected to each other and configured to transmit a processed signal originating from an input sound picked up by the microphone, the loudspeaker signal path comprising a receiver unit, an SSP-signal processing unit comprising an SSP-filter, and a loudspeaker unit operationally connected to each other and configured to provide an acoustic sound signal originating from a signal received by the receiver unit. The application further relates to a method of operating a communications device and to its use. The object of the present application is to provide an alternative scheme for controlling echo suppressing in a communication device, e.g. a speakerphone. The problem is solved in that the communication device comprises a control unit for - e.g. in a specific echo suppression mode - dynamically controlling the filtering characteristics of the MSP and SSP-filters based on one or more control input signals. This has the advantage of providing a simple and flexible scheme for decreasing echo in a communication device, while ensuring an acceptable sound quality in the transmitted signal. The invention may e.g. be used in handsfree telephone systems, mobile telephones, teleconferencing systems, public address systems, karaoke systems, classroom amplification systems, etc.