Hearing Aid Two-Channel Noise Reduction
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Solution Overview
Problem
Existing hearing devices struggle to reduce background noise effectively while maintaining a natural sound image, often resulting in unnatural hearing impressions due to complete suppression of quiet noises and challenges in setting thresholds for noise reduction algorithms.
Innovation Solution
A hearing device with two signal processing channels, one with integrated noise reduction and the other with level limitation, where the output signals are added to form a total output signal, allowing passive noise reduction without active level-dependent control, ensuring quiet noises are not lost and maintaining a natural sound image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise reduction algorithms are used to suppress disturbing noises, then background noise is reduced effectively, but quiet noises are completely reduced below the threshold of hearing leading to an unnatural hearing impression
Solution Approach 1:
The signal processing is divided into two separate channels: a first signal processing channel with noise reduction and a second signal processing channel without noise reduction but with level limitation. These channels are processed independently and then combined, allowing different treatments for different signal components.
Solution Approach 2:
The invention changes the parameter of noise reduction strength based on the ambient sound level. At low ambient levels, the effective noise reduction is reduced or eliminated to preserve quiet noises. At higher ambient levels, full noise reduction is applied. This is achieved through the interaction of the two channels with different processing characteristics.
2Loss of information
If noise reduction is switched off automatically at low ambient levels, then quiet noises are preserved, but setting the threshold causes a restless sound image around the threshold level
Solution Approach 1:
The system dynamically adjusts the effective noise reduction based on the ambient sound level without requiring explicit threshold switching. The level limiting device in the second channel naturally adapts its behavior to the input signal level, providing smooth transitions and avoiding the restless sound image associated with fixed threshold switching.
Solution Approach 2:
The level limiting device acts as an intermediary element that indirectly controls the amount of noise reduction applied. Instead of directly switching noise reduction on/off at a threshold, the level limiter modulates the contribution of the noise-reduced signal based on the ambient level, creating a smooth transition.
3Loss of information
If manual switching off of noise reduction is implemented, then quiet noises are preserved, but user comfort is significantly reduced
Solution Approach 1:
The hearing device automatically adapts its noise reduction behavior based on the ambient sound level without requiring user intervention. The level limiting device and noise reduction device work together to self-regulate the processing, eliminating the need for manual switching while preserving quiet noises in appropriate conditions.
4Object-affected harmful factors
If stronger noise reduction is applied, then background noise is reduced more effectively, but detail in the sound is lost
Solution Approach 1:
By separating the signal processing into two channels and combining them, the invention preserves sound details that would otherwise be lost in aggressive noise reduction. The level-limited channel maintains the original signal characteristics while the noise-reduced channel provides cleaner background, and their combination preserves both detail and noise reduction.
Data Source
Figure 1~2
AI summary
The aim is to provide a hearing device, and in particular a hearing aid, that reduces background noise while maintaining the most natural sound possible. To this end, a hearing device is proposed with a first signal processing channel (K1) in which a noise reduction device (11) is integrated, and a second signal processing channel (K2) that has the same input as the first signal processing channel (K1) but does not include a noise reduction device, but does include a level limiting device (12). An additive device (13) adds the output signals of both signal processing channels (K1, K2) to form a total output signal (SG). This enables passive, input-level-dependent noise reduction, allowing quiet signals to be heard despite the noise reduction.