Hearing Device Dual Microphone Feedback Reduction
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Solution Overview
Problem
Conventional hearing aids face challenges in improving sound quality and directional response due to acoustic feedback and the comb filter effect, which are exacerbated by the placement of microphones in the ear canal and the pinna, leading to suboptimal spatial cue preservation and amplification.
Innovation Solution
A hearing device with two input sound transducers, one in the ear canal and one behind the pinna, processes electrical signals from both to determine a level difference, which is used to generate an output sound signal, improving sound quality and directional response by compensating for feedback and optimizing microphone placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microphone is placed in the ear canal to capture sound, then the device structure is simple, but feedback and comb filter effects occur leading to degraded sound quality
Solution Approach 1:
The patent divides the single microphone function into two separate microphones: one in the ear canal (first microphone) and one behind the pinna (second microphone). Each microphone captures sound from different locations, allowing the system to process multiple sound paths independently and combine them to reduce feedback and comb filter effects while maintaining simple individual microphone structures.
2Measurement precision
If microphones are placed in the ear canal to capture sound directly, then spatial hearing is improved, but feedback and comb filter effects are exacerbated
Solution Approach 1:
The patent introduces a processing unit that acts as an intermediary between the two microphones and the output. This processing unit analyzes sound from both microphones, determines level differences, and combines the signals in a way that preserves spatial hearing information while canceling out feedback and comb filter effects through computational processing.
3Reliability
If a second microphone is added behind the pinna to reduce feedback, then sound quality improves, but device complexity increases
Solution Approach 1:
The patent merges the functions of two microphones (one in ear canal, one behind pinna) with a processing unit that combines their outputs. The processing unit merges the sound paths by determining level differences and combining signals appropriately, achieving improved sound quality and feedback reduction while managing the complexity through integrated signal processing.
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 enhances sound quality and directional response by reducing feedback and the comb filter effect, allowing for better spatial hearing and consonant enhancement, while also increasing design freedom for the hearing device's housing.
Implementation Method 1
receive acoustical sound signals from the environment for generating a first electrical acoustic signal in accordance with the received acoustical sound signals
Implementation Method 2
receive acoustical sound signals from the environment for generating a second electrical acoustic signals in accordance with the received acoustical sound signals
Implementation Method 3
generate an acoustical output sound signal in accordance with the electrical output sound signal
Data Source
AI summary
A hearing device comprising a first and a second input sound transducers, a processing unit, and an output sound transducer. The first transducer is configured to be arranged in an ear canal or in the ear of the user, to receive acoustical sound signals from the environment and to generate first electrical acoustic signals from the received acoustical sound signals. The second transducer is configured to be arranged behind a pinna or on, behind or at the ear of the user, to receive acoustical sound signals from the environment and to generate second electrical acoustic signals from the received acoustical sound signals. The processing unit is configured to process the first and second electrical acoustic signals and apply a direction dependent gain. The output sound transducer is configured generate acoustical output sound signals in accordance with the applied direction dependent gain.