Hearing Aid Phase Modulation for Reduced Comb Filter Perception
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Solution Overview
Problem
Hearing devices with open fitting configurations suffer from comb filter effects, leading to unnatural sound perception due to acoustic feedback, which existing methods like high pass filtering or using closed earpieces cannot adequately address without compromising comfort or information content.
Innovation Solution
A method and device that detect head movements using sensors to phase-modulate and amplify acoustic signals, simulating natural sound integration and cancellation of comb filter effects by varying the phase position of the signal, allowing the brain to reduce perceivable comb filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open fitting earpieces are used to improve wearing comfort and ventilation, then comb filter effects occur due to acoustic feedback
Solution Approach 1:
The patent applies dynamics by making the earpiece configuration changeable between open and closed states. The earpiece can dynamically switch between open fitting (for comfort and ventilation) and closed fitting (for preventing comb filter effects), allowing the system to adapt to different listening conditions and user preferences, thus resolving the contradiction between comfort and acoustic feedback prevention
Solution Approach 2:
The patent changes the acoustic parameter of the earpiece by introducing a movable closure element that can alter the acoustic impedance and sound permeability of the earpiece. This parameter change allows transition between open and closed states, enabling the system to eliminate comb filter effects while maintaining wearing comfort through selective configuration changes
2Object-generated harmful factors
If closed earpieces are used to reduce comb filter effects, then wearing comfort and ventilation are compromised
Solution Approach 1:
The patent makes the earpiece dynamically configurable between closed and open states. The closure element can be moved to create a closed fitting that prevents comb filter effects, or retracted to provide an open fitting for comfort and ventilation, allowing users to switch between modes based on their needs
Solution Approach 2:
The patent changes the acoustic sealing parameter of the earpiece by introducing a movable closure element that can seal or open the earpiece interface. This allows the system to switch between acoustic isolation (reducing comb filter) and acoustic ventilation (improving comfort) states
3Object-generated harmful factors
If high pass filtering is applied to reduce comb filter perception, then information content of the signal is restricted
Solution Approach 1:
Instead of using high pass filtering to remove low frequencies (which loses information), the patent inverts the approach by using closed earpiece configurations to physically prevent the acoustic feedback that causes comb filter effects. This eliminates the harmful effect while preserving the full frequency spectrum and information content of the audio signal
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
Effectively reduces the perception of comb filter effects by mimicking natural sound processing, enhancing comfort and maintaining information integrity without the drawbacks of closed earpieces.
Implementation Method 1
at least one motion sensor (11) connected to said signal processing unit (9) and configured to detect a head movement of a wearer of the hearing device (1)
Implementation Method 2
said signal processing unit (9) including means for modulating a phase of an acoustic signal, wherein said modulating means, upon detection of a head movement of the wearer of the hearing device (1), modulates the signal detected by said at least one microphone (3)
Data Source
AI summary
A method of operating a hearing device monitors for a head movement of a hearing device wearer. When a head movement is detected, an acoustic signal acquired by a microphone is output in an amplified and phase-modulated manner with a receiver. Furthermore, a hearing device includes a motion sensor and a signal processing unit that is configured to execute the method.