Loudspeaker Feedback Sense Element for Echo Cancellation
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Solution Overview
Problem
Conventional speakerphone systems face challenges with acoustical feedback and nonlinearities in audio output, limiting their effectiveness in preventing echo and distortion, and restricting them to half-duplex operations.
Innovation Solution
The system employs a feedback sense element positioned differently from the microphone to sense and process audio signals from a loudspeaker, using echo cancellation and linearization techniques to attenuate feedback and reduce distortion, enabling improved audio quality and transitioning towards full-duplex functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If acoustic separation between microphone and loudspeaker is implemented, then echo and interference are prevented, but device complexity and space requirements increase
Solution Approach 1:
The patent implements feedback by positioning a sense element near the loudspeaker to detect acoustic output, processing this feedback signal to model the acoustic transfer function, and using this model to predict and cancel echo at the microphone. This allows effective echo prevention without requiring significant acoustic separation between components.
Solution Approach 2:
The sense element acts as an intermediary between the loudspeaker and the echo cancellation system. It captures the loudspeaker's acoustic output and converts it to an electrical signal that can be processed to predict the echo at the microphone, enabling precise echo cancellation without physical separation.
2Device complexity
If linear assumption of loudspeaker output is used, then processing is simplified, but accuracy in predicting acoustical feedback deteriorates
Solution Approach 1:
The system performs preliminary action by using the sense element to capture the loudspeaker's actual acoustic output before it reaches the microphone. This captured signal is processed to create an accurate model of the acoustic transfer function, which is then used to predict and cancel the echo with high precision.
Solution Approach 2:
The patent changes the parameter being measured from the electrical drive signal to the actual acoustic output signal. By using the sense element to capture the real acoustic waveform produced by the loudspeaker, the system accounts for nonlinearities and distortion in the loudspeaker's operation, significantly improving prediction accuracy.
3Measurement precision
If echo cancellers and non-linear processing are implemented, then prediction accuracy improves, but device complexity and processing requirements increase
Solution Approach 1:
The system uses the loudspeaker's own acoustic output, captured by the sense element, to generate the echo cancellation signal. This self-service approach eliminates the need for separate training data or complex adaptive filtering, achieving high accuracy with relatively simple processing.
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
This approach effectively reduces acoustical feedback and nonlinearities, enhancing audio clarity and enabling full-duplex speakerphone operations by using a feedback sense element to process and correct audio signals in real-time.
Implementation Method 1
a feedback sense element configured to sense an audio signal from the loudspeaker
Implementation Method 2
using echo cancellation and linearization techniques to attenuate feedback
Implementation Method 3
a loudspeaker configured to provide an audible signal based on the audio signal
Data Source
AI summary
An electronic device comprises a microphone, a transceiver circuit, a loudspeaker, a sense element and a processing circuit. The microphone is configured to receive a first audio signal. The transceiver circuit is configured to communicate the first audio signal to a remote device and to receive a second audio signal from the remote device. The loudspeaker is configured to provide an audible signal based on the second audio signal. The sense element is configured to sense the audible signal provided by the loudspeaker. The sense element may be positioned at a distance from the loudspeaker different than a distance between the microphone and the loudspeaker. The processing circuit is configured to process at least one of the first audio signal and the second audio signal based on a sensed signal from the sense element.