Acoustic Feedback Suppression in Communication Terminals
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Solution Overview
Problem
Acoustic feedback between communication terminals in radio-based networks for mobile voice and/or data communication leads to noise and system instability, especially when devices are in close proximity and at increased volume, existing solutions like echo processing devices and echo reducers are not entirely effective in preventing feedback loops.
Innovation Solution
A method and device that determine the presence of an acoustic feedback loop using a feedback loop detector, reduce signal intensity between the microphone and loudspeaker, and employ an acoustic echo controller to dampen echoes, estimating the probability of feedback occurrence by analyzing near-end and far-end signals and their coherence to adjust signal amplification and prevent feedback loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the volume of the speaker is increased, then the transmission quality is improved, but noise and system instability occur due to acoustic feedback
Solution Approach 1:
The patent employs feedback mechanisms through the feedback loop detector that continuously monitors acoustic feedback conditions and adjusts speaker output accordingly. The system detects feedback loops and modifies the audio signal to prevent instability while maintaining high volume operation.
Solution Approach 2:
The patent replaces direct acoustic feedback suppression with electronic signal processing. Instead of relying on physical distance or absorption materials, the system uses electronic detection and control to monitor and adjust audio signals, preventing feedback loops through digital signal analysis and control.
2Ease of operation
If two communication devices are placed in close proximity, then the ease of operation is improved, but acoustic feedback loops occur
Solution Approach 1:
The feedback loop detector continuously monitors the acoustic environment and detects feedback loops caused by close device placement. When feedback is detected, the system adjusts the audio signal to eliminate the harmful feedback while allowing the devices to remain in close proximity for ease of use.
Solution Approach 2:
The patent substitutes physical separation solutions with electronic signal processing. Instead of requiring devices to be physically distant to avoid feedback, the system uses electronic detection and control to eliminate feedback loops, allowing close proximity operation.
3Object-generated harmful factors
If existing echo processing devices are used, then some echo suppression is achieved, but feedback loops cannot be fully prevented
Solution Approach 1:
The patent enhances existing echo processing by adding dedicated feedback loop detection capabilities. The feedback loop detector specifically monitors for feedback conditions and provides control signals to prevent feedback loops, building upon existing echo suppression technologies with specialized feedback prevention.
Solution Approach 2:
The patent improves upon existing echo processing devices by replacing their limited echo suppression with a comprehensive electronic detection and control system. The feedback loop detector uses electronic signal analysis to identify feedback conditions and control the audio output to prevent feedback loops entirely.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable communication between devices in the same acoustic space without significant acoustic feedback, reducing noise and system instability by predicting and mitigating feedback loops, thereby enhancing communication reliability.
Implementation Method 1
estimating the probability of the acoustic feedback loop occurring, including a near-end signal and a far-end signal, with the near-end signal corresponding to an acoustic echo which is produced by feedback of the first acoustic signal received from the second communication terminal from the loudspeaker to the second microphone
Implementation Method 2
The acoustic echoes between the loudspeaker of the second communication terminal and a second microphone are damped by means of an acoustic echo controller, the second microphone being part of the second communication terminal, the acoustic echo controller receiving the first acoustic signal from the microphone from the second communication terminal of the first communication terminal receives as the first input signal and receives a second acoustic signal received from the second microphone as the second input signal
Data Source
Figure 1
AI summary
The method involves providing a signal-technical coupling (310) between a microphone (110) of a communication terminal (100) and a loudspeaker (220) of another communication terminal (200). An existence of an acoustic feedback loop between the terminals is determined by a feedback loop-detector (400). The feedback loop is conditioned by feedback (340) of an acoustic signal (330) in the microphone over the loudspeaker. A signal intensity between the microphone and the loudspeaker is reduced by a signal gain control when the existence of the feedback loop is determined. An independent claim is also included for a communication terminal.