Adaptive Filter for Behind-the-Ear Microphone Audio Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Behind-the-ear (BTE) hearing aids face challenges in adapting audio captured by BTE microphones to sound closer to what is naturally received by the wearer's ear canal, due to positional and geometrical differences.
Innovation Solution
The system utilizes sound captured by a front-of-ear microphone to dynamically adapt sound captured by one or more BTE microphones, employing an adaptive filter to minimize errors and compensate for differences in sound reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If BTE microphones are positioned behind the ear, then the device structure is simple and easy to manufacture, but the captured sound does not match the natural sound received at the ear canal
Solution Approach 1:
The patent introduces an intermediary adaptive filter system that processes the audio signal from the BTE microphone. The filter uses transfer function estimation to create a virtual model of the ear canal acoustics, acting as a mediator between the BTE microphone position and the desired ear canal sound experience. This allows the system to achieve accurate sound capture without physically placing the microphone in the ear canal.
2Measurement precision
If feed-forward microphones are positioned within the ear canal, then sound capture accuracy is improved, but acoustic coupling to the transducer causes audio feedback
Solution Approach 1:
The patent extracts the sound capture function from the ear canal position and relocates it to the BTE microphone position behind the ear. By separating the capture location from the playback location and using digital signal processing to bridge the gap, the system eliminates the acoustic coupling path that causes feedback while maintaining accurate sound capture through adaptive filtering.
3Measurement precision
If adaptive filtering is implemented to adapt audio from BTE microphones, then sound quality is improved, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-calculating and storing transfer functions that characterize the acoustic path from the BTE microphone position to the ear canal. These pre-computed transfer functions are then applied during normal operation through efficient convolution operations, avoiding the need for real-time complex adaptive filtering and reducing computational complexity while maintaining sound quality.
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 adapts the audio to better match the natural sound received by the ear canal, particularly improving high-frequency sound spectra, thereby enhancing the audio experience for BTE hearing aid users.
Implementation Method 1
The BTE microphone signal is provided to an adaptive filter, such as a least mean squares (LMS) filter. The adaptive filter generates an adapted signal based on the BTE microphone signal and an error signal.
Implementation Method 2
The error signal is generated by a subtractor circuit, and represents the difference between the adapted signal generated by the adaptive filter and the front-of-car microphone signal generated by the front-of-car microphone.
Implementation Method 3
The processed adapted signal is then played by the acoustic transducer for the user to hear.
Data Source
AI summary
A wearable audio device, such as a hearing aid is provided. The wearable audio device includes a BTE microphone, a front-of-ear microphone, an adaptive filter, a subtractor circuit, and an acoustic transducer. The BTE microphone generates a BTE microphone signal. The BTE microphone may be arranged behind an ear of a user. The front-of-ear microphone generates a front-of-ear microphone signal. The front-of-ear microphone may be arranged within an ear canal or a concha of the ear of the user. The adaptive filter generates an adapted signal based on the BTE microphone signal and an error signal. The subtractor circuit generates the error signal based on the adapted signal and the front-of-ear microphone signal. The acoustic transducer generates audio based on the adapted signal. In some examples, the wearable audio device includes a plurality of BTE microphones configured as a directional microphone array.