Open-Ear Hearing Device AFC for Acoustic Feedback Control
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Solution Overview
Problem
Existing hearing devices, particularly open ear devices like smart glasses and hearing aids, suffer from acoustic feedback issues due to the proximity of microphones and loudspeakers, limiting maximum stable gain and sound quality.
Innovation Solution
Implementing adaptive feedback cancellation systems using beamformers, adaptive feedback cancellers (AFCs), and phase shifters to process audio signals from multiple microphones, estimating transfer functions, and applying feedforward processing to minimize acoustic feedback and enhance sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If microphones and loudspeakers are positioned close together in open ear devices, then device compactness is improved, but acoustic feedback increases
Solution Approach 1:
The patent introduces an adaptive feedback canceller (AFC) as an intermediary component that processes audio signals to estimate and remove feedback paths. The AFC independently processes signals from multiple microphones, acting as a mediator between the close-positioned microphones and loudspeaker to eliminate the harmful acoustic feedback while maintaining the compact device structure.
Solution Approach 2:
The patent divides the audio signal processing into separate independent channels for each microphone. The AFC independently processes the first and second digital audio signals, segmenting the feedback cancellation task into manageable parts that can be handled separately, thereby effectively managing acoustic feedback in the compact device configuration.
2Object-affected harmful factors
If acoustic feedback is reduced using traditional methods, then feedback noise is minimized, but maximum stable gain is limited
Solution Approach 1:
The patent implements an adaptive feedback canceller that continuously estimates transfer functions and updates its parameters based on the acoustic feedback it detects. This feedback mechanism allows the system to dynamically adjust and optimize feedback cancellation, achieving lower feedback noise while maintaining higher maximum stable gain compared to traditional fixed methods.
Solution Approach 2:
The system dynamically changes processing parameters including phase shifts and transfer function estimates based on real-time acoustic conditions. By adapting parameters rather than using fixed values, the system achieves better feedback noise reduction while preserving maximum stable gain capability.
3Object-generated harmful factors
If multiple microphones are used with independent processing, then acoustic feedback reduction is improved, but device complexity increases
Solution Approach 1:
The patent divides the complex multi-microphone signal processing into independent, manageable segments. Each microphone's digital audio signal is processed independently by the AFC, which estimates transfer functions separately for each channel. This segmentation approach improves acoustic feedback reduction while keeping the processing complexity organized and manageable through modular independent operations.
Data Source
AI summary
Methods and systems are described for mitigating acoustic feedback via an open ear device. In various examples, systems or methods may receive, via a first microphone and a second microphone positioned on an open ear device, a first audio signal and a second audio signal, respectively. The first audio signal and second audio signal may be converted to a first digital audio signal and a second digital audio signal. The first digital audio signal and second digital audio signal may be independently processed by an AFC to reduce acoustic feedback. A beamformer may adjust the first digital audio signal and second digital audio signal based on a target direction to create a beamformer digital audio signal. The beamformer digital audio signal may be processed via feedforward processing to create a target audio. The target audio may be phase shifted and transmitted to a loudspeaker positioned on the open ear device.