Hearing Aid Comb Filtering Reduction via Frequency-Domain Attenuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hearing aids experience comb filtering due to the superposition of sound processed through the device and direct sound leaking into the ear canal, causing distortion and discomfort for wearers.
Innovation Solution
A method that determines the effective time delay between direct and amplified sound paths, calculates cancellation frequencies, identifies spectral interaction regions, and constructs filters to reduce comb filtering by applying attenuation in specific frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If venting is provided in hearing aids to allow direct sound path, then natural sound perception is improved, but comb filtering distortion occurs due to interference between direct and amplified sound paths
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the attenuation coefficient and filter characteristics based on the calculated comb filtering frequencies. The system modifies the frequency response parameters in real-time to cancel out the harmful interference patterns while preserving the beneficial venting effect for natural sound perception.
Solution Approach 2:
The patent converts the harmful comb filtering effect into a benefit by using the known interference pattern to create targeted attenuation filters. The system calculates the specific frequencies where comb filtering occurs and applies precise attenuation at those frequencies, thereby eliminating the distortion while maintaining the natural sound path benefits.
2Reliability
If amplification path is used to assist hearing, then hearing loss compensation is improved, but time delay relative to direct sound causes comb filtering
Solution Approach 1:
The patent applies preliminary action by calculating the effective time delay and determining the comb filtering frequencies before applying the attenuation filter. The system proactively compensates for the anticipated delay-induced interference by pre-configuring the filter parameters based on the measured or estimated time delay between direct and amplified sound paths.
3Object-affected harmful factors
If frequency domain filtering is applied to reduce comb filtering, then sound quality is improved, but computational complexity increases
Solution Approach 1:
The patent applies local quality by implementing frequency-selective attenuation that targets only the specific frequencies where comb filtering occurs, rather than applying broad-spectrum processing. The system calculates the precise cancellation frequencies based on the time delay and applies localized attenuation at those frequencies, minimizing unnecessary computational overhead while effectively reducing distortion.
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
The solution effectively mitigates comb filtering, improving sound quality for hearing aid wearers by reducing distortion and discomfort without requiring hardware changes or excessive processing power.
Implementation Method 1
The superposition of sound processed through a hearing aid and the direct path sound leaking into the ear canal can cause comb filtering
Implementation Method 2
the sum of the sounds from the two paths produces comb filtering which may cause distortion or discomfort
Data Source
AI summary
Disclosed herein, among other things, are systems and methods for reducing the comb filtering for hearing devices. A method includes determining an effective time delay as a function of frequency between a direct path from a sound source to an eardrum of a wearer of a hearing device and an amplified path from the sound source through the hearing device to the eardrum of the wearer, and calculating a set of cancellation frequencies based at least in part on the determined effective time delay. The method also includes comparing an aided gain response and a real-ear occluded gain response of the hearing device, and determining one or more spectral interaction regions based at least in part on the comparison. A subset of cancellation frequencies is determined by comparing the spectral interaction regions with the set of cancellation frequencies, and a filter is constructed using the subset of cancellation frequencies and a determined attenuation configured to reduce comb filtering.