Hearing Aid Digital Noise Filtering via Autocorrelation
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Solution Overview
Problem
Current hearing aids face challenges in reducing inherent noise generated by telecoil input devices, particularly in wireless systems, where broadband noise from digital signal processing can be difficult to eliminate using simple filters, potentially affecting audio quality.
Innovation Solution
A method involving digital filtering that separates the input signal into time samples, applies low-pass filters to remove noise components synchronized with the signal processor's or transmitter's periodicity, and recombines the samples to reduce noise, using adaptive time constants and filter coefficients based on the input signal's RMS value to effectively suppress both audio streaming and data connection noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital signal processing and wireless transmission are implemented in hearing aids, then functionality and connectivity are improved, but broadband noise is generated that is difficult to remove with simple filters
Solution Approach 1:
The patent segments the noise reduction process into multiple stages: first identifying periodic noise components using autocorrelation, then removing them through spectral subtraction, and finally applying conventional filtering. This multi-stage segmentation allows effective noise reduction without compromising the audio signal quality.
Solution Approach 2:
The patent performs preliminary noise characterization by analyzing the autocorrelation of the input signal to identify periodic noise components before the main signal processing occurs. This preliminary action enables the system to prepare appropriate filter coefficients and noise profiles in advance, improving the effectiveness of subsequent noise reduction.
2Adaptability or versatility
If telecoil input devices are used for wireless connectivity, then connection capabilities are improved, but inherent noise from the telecoil input is generated
Solution Approach 1:
The patent introduces an intermediary noise profile that characterizes the periodic noise from telecoil input. By creating this intermediate representation of the noise characteristics, the system can selectively remove noise components without affecting the desired audio signal, thus maintaining connection capabilities while reducing inherent noise.
3Device complexity
If simple digital linear filters are used for noise reduction, then implementation complexity is reduced, but noise removal effectiveness is insufficient for broadband noise
Solution Approach 1:
The patent implements dynamic filter coefficients that adapt to the characteristics of the input signal. By using autocorrelation analysis to identify periodic noise components and adjusting filter parameters accordingly, the system achieves effective broadband noise removal without requiring overly complex fixed filter designs.
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 significantly reduces broadband noise in the digital signal, improving audio quality by isolating and subtracting periodic noise components, making the method more robust against varying noise levels and ensuring effective noise suppression without affecting the desired audio signal.
Implementation Method 1
Each time sample is filtered via a low pass filter such that a noise component of the noise signal is removed
Data Source
AI summary
The invention relates to a method of operating an electronic device (6), the device (6) comprising a receiver (8) for receiving a wireless analogue signal (10), a converter (12) for converting the received analogue signal (14) to a digital input signal (16, 16′), a signal processor (18) for generating a digital output signal (20) from the input signal (16, 16′), and a transmitter (22) for transmitting the output signal (20) as a wireless digital signal (24), wherein the input signal (16′) is filtered to generate the output signal (20) such that a noise signal (30) in the input signal (16′) generated by the signal processor (18) and/or the transmitter (22) is reduced.