Hearing Aid Noise Compensation via Spectral Band Segmentation
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Solution Overview
Problem
Hearing devices, such as hearing aids, face challenges in effectively compensating for background noise due to the lack of specialized components necessary for active noise cancellation, leading to inadequate noise path attenuation and interference with ventilation, resulting in suboptimal noise reduction.
Innovation Solution
A method that determines a specific spectral band based on the user's hearing ability and filters the input signal using a transfer function corresponding to the noise path, generating a phase-inverted compensation sound to effectively cancel background noise without requiring specialized components, utilizing a recursive linear filter or adaptive filter to minimize group delay and computational resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active noise cancellation is implemented using conventional transducers in a hearing aid, then noise compensation is achieved, but the system exhibits excessive group delay and cannot provide compensated sound with correct phase
Solution Approach 1:
The invention divides the frequency spectrum into multiple spectral bands and processes each band separately with its own transfer function. This segmentation allows optimization of group delay for each frequency range, enabling accurate phase compensation that would be impossible with a single broadband filter.
Solution Approach 2:
The patent applies different transfer functions tailored to specific spectral bands rather than a uniform approach across all frequencies. Each spectral band receives customized filtering parameters optimized for its characteristics, achieving local optimization of noise cancellation performance and phase accuracy.
2Object-affected harmful factors
If noise attenuation is increased in the ventilation opening, then background noise reaching the eardrum is reduced, but air exchange between the wearer's environment and ear canal is impaired
Solution Approach 1:
The invention replaces mechanical noise blocking (which would require physical obstruction of the vent) with electronic signal processing. The anti-noise signal is generated electronically and injected into the ear canal, achieving noise cancellation without any physical barrier to air flow through the ventilation opening.
Solution Approach 2:
The patent introduces an electronic intermediary (the anti-noise signal generated by the processing unit) that mediates between the noise source and the eardrum. This intermediary signal cancels the harmful noise through destructive interference, allowing the ventilation opening to remain physically open for air exchange.
3Loss of time
If hearing aids use specialized transducers designed for active noise cancellation, then group delay is reduced and phase accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The invention achieves the performance of specialized transducers by changing the parameters of conventional components - specifically by applying sophisticated digital signal processing algorithms and multiple spectral band transfer functions to standard hearing aid transducers. This software-based parameter optimization replaces the need for specialized hardware.
Solution Approach 2:
The patent creates a digital copy or model of the ideal noise cancellation behavior through computational algorithms. Rather than physically specialized transducers, the system uses software-based transfer functions that replicate the desired frequency and phase characteristics, achieving equivalent performance through mathematical modeling.
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 allows for targeted noise cancellation in specific spectral bands where the user hears most noise, improving noise reduction while maintaining ventilation and other hearing device functionalities, with minimal computational effort and adaptability to individual hearing profiles.
Implementation Method 1
The compensating sound is phase-inverted. It thus compensates for the pressure fluctuations in the ear canal that would otherwise be caused by the ambient noise. In other words, the ambient noise and the compensating sound cancel each other out through their superposition.
Implementation Method 2
the ambient noise and the compensating sound cancel each other out through their superposition
Implementation Method 3
without these special components, it is impossible to provide a compensated sound with correct phase
Data Source
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AI summary
In a hearing device (8), the aim is to prevent sound (11) from the surroundings of an ear (6, 7) of a wearer of the hearing device from reaching the eardrum (13) of the wearer as an interfering sound (12), for example, through a ventilation opening (9). Unlike hearing aids specifically designed for noise protection, many hearing devices do not allow for broadband compensation of such interfering sound (12) using active noise cancellation. These hearing devices lack the necessary specialized components. Therefore, a compensation sound signal with correct phase cannot be generated. According to the invention, a compensation sound (15) is generated only for a relatively narrow spectral band.This spectral band is determined depending on the hearing ability of the wearer of the hearing device and/or depending on the spectral distribution of the energy of the background noise (12) or of a sound (11) causing the background noise (12). The invention is particularly suitable for compensating for background noise (12) in a hearing aid (8).