Hearing Protector With Unidirectional Sound Inlet
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Solution Overview
Problem
Conventional hearing protectors reduce sound quality and hinder directional hearing, making it difficult for users to determine the origin of sounds, especially in noisy environments.
Innovation Solution
A hearing protector with a cup-shaped shell and a sound inlet formed by an acoustic membrane that unidirectionally weakens the sound barrier, allowing for improved sound transmission from the anterior direction, enabling directional hearing by creating a level difference in sound levels based on direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hearing protector provides strong passive noise dampening, then the wearer's hearing is protected from harmful noise levels, but the wearer cannot determine the direction of sound sources
Solution Approach 1:
The shell is segmented into different regions with different acoustic properties: a first region (anterior) with reduced sound attenuation and a second region (posterior) with strong sound attenuation. This segmentation allows the hearing protector to simultaneously provide directional hearing information and hearing protection by directing sounds from different directions through different paths.
Solution Approach 2:
Different regions of the shell have different acoustic qualities: the anterior region has sound inlet openings that reduce attenuation for directional perception, while the posterior region maintains strong attenuation for protection. This local differentiation of acoustic properties enables the device to fulfill both protective and directional hearing functions.
2Loss of energy
If a hearing protector uses a complete sound barrier shell, then noise dampening is maximized, but sound quality and directional perception are reduced
Solution Approach 1:
The complete shell is divided into a first region with sound inlet openings and a second region forming a sound barrier. This segmentation allows sounds to reach the ear through two different paths, preserving sound quality for directional perception while maintaining noise attenuation through the barrier region.
Solution Approach 2:
The sound inlet openings act as intermediaries that selectively transmit sounds from the anterior direction while the sound barrier region mediates the attenuation of noises from other directions. This intermediary structure enables the coexistence of sound quality preservation and noise dampening.
3Reliability
If a hearing protector provides uniform sound attenuation in all directions, then hearing protection is consistent, but the wearer cannot perceive the origin direction of sounds
Solution Approach 1:
The shell is designed with asymmetric acoustic properties: the anterior region has sound inlet openings for directional perception while the posterior region has sound barrier characteristics for protection. This asymmetric design breaks the uniformity of sound attenuation, enabling directional hearing while maintaining protective function.
Solution Approach 2:
Instead of providing uniform attenuation, the design inverts the approach by creating a directional sound inlet in the anterior region while maintaining strong attenuation in the posterior region. This inversion allows the wearer to perceive sound directions by comparing the asymmetric acoustic input from different directions.
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
Enhances wearer comfort and safety by allowing better perception of sound direction, even in noisy conditions, by providing a significant level difference in sound frequencies, facilitating the recognition of sound sources.
Implementation Method 1
a sound inlet that is formed of at least one acoustic membrane and that replaces a portion of the shell... the sound inlet locally reduces the sound barrier of the shell predominantly with respect to sound originating from an anterior direction
Data Source
Figure 1
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Figure 4~5
AI summary
There is provided a hearing protector that has an earmuff (2) formed by a cup-shaped shell and a cushion. The hearing protector has a sound inlet (5) formed of at least one acoustic membrane that replaces a portion of the shell or by a hole into the cushion. The sound inlet locally reduces the sound barrier of the hearing protector predominantly with respect to sound originating from an anterior direction (11) that is defined in accordance to on the anatomic directions of a wearer when the hearing protector is worn. The present disclosure helps enabling directional hearing with a hearing protector.