In-Ear Hearing Device Acoustic Volume Partitioning
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Solution Overview
Problem
Hearing devices face challenges in achieving consistent acoustic performance due to dependency on acoustic load impedance, which varies with individual ear geometry and sealing quality, affecting low-frequency sensitivity and mechano-acoustic resonance peak.
Innovation Solution
Incorporating a hearing device design with an acoustic transducer partitioning the housing into two volume portions, acoustically coupled by a resistive member in parallel and another resistive member in series with the acoustic port, to stabilize frequency response and output impedance, allowing for customization and improved sound delivery across different ear canals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the second volume portion is left open to the ambient environment, then low-frequency sensitivity is improved, but mechano-acoustic resonance peak becomes dependent on acoustic load impedance
Solution Approach 1:
The patent divides the acoustic system into multiple volume portions (first volume portion in front of the acoustic transducer and second volume portion behind it) separated by a partition. This segmentation allows independent acoustic treatment of each volume, enabling the first volume to be open for low-frequency sensitivity while the second volume can be acoustically coupled to ambient environment through controlled ports for resonance stability.
Solution Approach 2:
Different acoustic properties are applied to different regions: the first volume portion has an acoustic port for low-frequency response, while the second volume portion has acoustic ports configured to provide mechano-acoustic resonance peak stability. The resistive member is strategically placed to provide acoustic resistance specifically where needed to decouple the resonance peak from acoustic load impedance variations.
2Reliability
If the second volume portion is fully closed, then mechano-acoustic resonance peak is kept constant, but low-frequency sensitivity becomes dependent on acoustic load impedance
Solution Approach 1:
By segmenting the acoustic volume into two separate portions with a partition, the patent enables independent acoustic coupling strategies: the first volume portion remains open to the ear canal for low-frequency sensitivity, while the second volume portion is acoustically coupled to ambient environment through controlled ports, allowing both requirements to be satisfied simultaneously.
Solution Approach 2:
The partition acts as an intermediary structure that separates the two volume portions and allows independent acoustic treatment. The resistive member serves as an acoustic mediator that provides controlled acoustic resistance to decouple the resonance peak from acoustic load impedance variations while maintaining low-frequency response.
3Reliability
If an acoustic port is added to vent the second volume portion, then both resonance peak and low-frequency sensitivity become more independent of acoustic load impedance, but a frequency dip occurs due to Helmholtz resonance
Solution Approach 1:
The patent converts the potentially harmful Helmholtz resonance effect into a beneficial feature by strategically positioning acoustic ports and resistive members. The acoustic ports that would normally cause frequency dips are configured to work with the resistive member to provide acoustic resistance, transforming the harmful resonance into a useful mechanism for stabilizing acoustic parameters while maintaining frequency response.
Solution Approach 2:
The patent changes the acoustic parameters by introducing a resistive member with specific acoustic resistance values and configuring acoustic ports with specific areas and lengths. These parameter changes transform the acoustic system to provide both independence from acoustic load impedance and stable frequency response, preventing the harmful frequency dip effect.
4Ease of operation
If acoustic resistance is placed in parallel to the acoustic port, then frequency damping can be controlled, but the effect depends on housing geometry constraints
Solution Approach 1:
By segmenting the acoustic volume into two separate portions with a partition, the patent creates independent acoustic pathways that allow flexible placement of resistive members. This segmentation decouples the acoustic resistance control from housing geometry constraints, as the resistive member can be positioned within the second volume portion independently of the overall housing shape.
Solution Approach 2:
The patent introduces a new spatial dimension by creating a separate second volume portion behind the acoustic transducer, allowing the resistive member to be positioned in this additional space. This dimensional separation provides freedom in placing acoustic resistance elements without being constrained by the housing geometry in traditional single-volume designs.
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 design stabilizes and customizes the acoustic properties, reducing dependency on acoustic load impedance, ensuring consistent frequency response and output impedance, enabling effective active noise cancellation and uniform sound delivery.
Implementation Method 1
an acoustic transducer with an oscillator element configured to produce sound waves
Implementation Method 2
a first resistive member and a second resistive member, each resistive member comprising a first terminal and a second terminal and configured to attenuate sound waves between the first terminal and the second terminal
Implementation Method 3
The acoustic port may provide an acoustic impedance corresponding to an acoustic mass
Implementation Method 4
the acoustic transducer is disposed inside the housing such that the inner housing volume is divided into a first volume portion and a second volume portion acoustically coupled by the oscillator element
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The disclosure relates to a hearing device comprising a housing (111) configured to be at least partially inserted into an ear canal and enclosing an inner volume (116) separated into a first volume portion (117, 118) and a second volume portion (117, 118) by a partition including an acoustic transducer (151, 251), wherein a sound outlet (122) and an acoustic port (135, 435, 615, 635, 735, 835, 911, 927, 949, 959, 970) is provided at the housing (111). To allow modification of acoustic properties inside the inner volume (116), the disclosure proposes a first resistive member (131, 171, 221, 371, 471, 571, 671, 771, 871, 901, 905, 926, 948, 955, 975) and a second resistive member (131, 171, 221, 371, 471, 571, 671, 771, 871, 901, 905, 926, 948, 955, 975), each configured to attenuate sound waves between a first terminal and a second terminal, wherein the first terminal of the first resistive member is acoustically connected to the acoustic transducer (151, 251) via the first volume portion (117, 118), and the first terminal of the second resistive member is acoustically connected to the acoustic transducer (151, 251) via the second volume portion (117, 118), and wherein the partition (115, 175, 215) includes the first resistive member placed in parallel to the acoustic transducer (151, 251).