Earpiece Chimney Coupling for Accurate Ear Canal Pressure Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hearing aids with active noise reduction (ANR) face limitations in noise cancellation performance due to the acoustic impedance introduced by the nozzle mesh, which interferes with the feedback microphone's ability to accurately sense ear canal pressure, thereby reducing the maximum noise cancellation achievable.
Innovation Solution
The feedback microphone is directly coupled to the nozzle mesh via a chimney, which creates a small volume around the microphone port to accurately measure ear canal pressure, and a channel is provided to maintain functionality even if the chimney is blocked by debris, along with a resonant tube to enhance noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mesh is disposed along the outlet of the housing to inhibit debris from entering the acoustic volume, then debris protection is improved, but acoustic impedance increases and interferes with the feedback microphone's ability to sense ear canal pressure accurately
Solution Approach 1:
The acoustic path is segmented into two separate channels: one channel leads from the acoustic volume through the mesh to the external environment, while another channel leads directly from the feedback microphone port to the external environment, bypassing the mesh. This segmentation allows the mesh to protect the acoustic volume from debris while the direct channel allows the microphone to sense ear canal pressure accurately without interference from the mesh.
Solution Approach 2:
A second channel acts as an intermediary path that allows the feedback microphone to access the external environment directly, mediating between the microphone port and the external world without requiring passage through the mesh. This intermediary channel eliminates the acoustic impedance barrier that would otherwise be introduced by the mesh.
2Measurement precision
If the feedback microphone is coupled to the nozzle mesh via a chimney to accurately measure ear canal pressure, then noise cancellation performance is improved, but the system becomes vulnerable to blockages by debris
Solution Approach 1:
The acoustic path is segmented into two independent channels: one through the chimney to the mesh, and another direct channel from the microphone port to the external environment. If the chimney becomes blocked by debris, the direct channel remains functional, ensuring continuous accurate pressure sensing without complete system failure.
Solution Approach 2:
The direct acoustic channel serves as a backup pathway that is prepared in advance to compensate for potential blockages in the chimney. This pre-configured alternative path cushions the system against the harmful effect of debris blockages, ensuring reliable operation even when the primary chimney path is obstructed.
3Measurement precision
If a channel is provided to acoustically couple the microphone port to the acoustic volume, then noise cancellation is improved, but device complexity increases
Solution Approach 1:
The acoustic coupling is achieved through segmentation of the acoustic path into distinct channels with specific functions. The first channel provides the primary acoustic coupling path, while the second channel provides a direct reference path. This segmentation allows for optimized acoustic performance while maintaining manageable structural complexity through modular design.
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 configuration significantly improves noise cancellation performance, particularly in the 10 Hz to 1 KHz range, by accurately sensing ear canal pressure and maintaining effective noise reduction despite potential blockages, while also reducing pressure fluctuations and enhancing efficiency.
Implementation Method 1
an electro-acoustic transducer arranged such that a first radiating surface of the transducer radiates acoustic energy into the first acoustic volume and a second radiating surface of the transducer radiates acoustic energy into the second acoustic volume
Implementation Method 2
The resonant tube and the first acoustic volume together define a Helmholtz resonator
Implementation Method 3
The channel has an acoustic impedance that is greater than an acoustic impedance of the chimney
Data Source
AI summary
An earpiece includes an electro-acoustic transducer and a housing that supports the electro-acoustic transducer such that the housing and the electro-acoustic transducer together define a first acoustic volume and a second acoustic volume. The electro-acoustic transducer is arranged such that a first radiating surface of the transducer radiates acoustic energy into the first acoustic volume and a second radiating surface of the transducer radiates acoustic energy into the second acoustic volume. A mesh is disposed along an outlet of the housing and is arranged to inhibit debris from entering the front acoustic volume. A first microphone is supported in the housing. The first microphone includes a microphone port for sensing pressure. A chimney surrounds the microphone port and mechanically couples the first microphone to the mesh.