Acoustic Filter Earplug for Frequency-Selective Sound Attenuation
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Solution Overview
Problem
Existing earplugs fail to provide uniform sound attenuation across all frequencies, leading to distorted and muffled hearing, as they often block some frequencies more than others, compromising hearing protection and sound experience.
Innovation Solution
The earplug features two sound paths with unique acoustic filters, each comprising an upper and lower acoustic port, acoustic mesh/membrane, and chamber, allowing for selective attenuation by adjusting the open area, air permeability, and stiffness of these components, enabling the user to switch between low and high attenuation modes without removing the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If foam earplugs are used to block out sound, then hearing protection is provided, but sound attenuation is uneven across frequencies resulting in unclear and muffled hearing
Solution Approach 1:
The earplug divides the sound path into multiple frequency-specific channels, each with its own attenuation characteristics. The filter assembly segments the broadband noise into different frequency bands that can be independently managed, allowing selective attenuation while preserving speech frequencies.
Solution Approach 2:
Different portions of the earplug structure provide different attenuation qualities. The filter assembly with its specific port configuration and acoustic properties provides frequency-selective attenuation, while the earplug body provides overall noise blocking. This local differentiation of function resolves the contradiction between uniform blocking and selective clarity.
2Object-affected harmful factors
If earplugs are designed to block as much sound as possible, then hearing protection is improved, but voice communication and sound experience are compromised
Solution Approach 1:
The earplug incorporates a rotatable filter assembly that allows dynamic adjustment of attenuation characteristics. Users can rotate the filter assembly to change the orientation of acoustic ports, thereby dynamically adjusting which frequencies are attenuated and which are permitted, enabling adaptation between noise blocking and voice communication modes.
Solution Approach 2:
The filter assembly's attenuation parameters are changed by rotation, which alters the effective opening area and acoustic impedance of the ports. This parameter change allows the same physical structure to provide different attenuation levels and frequency responses, resolving the contradiction between maximum blocking and communication capability.
3Object-affected harmful factors
If a membrane element is used to create an airtight seal, then sound blocking is improved, but an uncomfortable sensation of vacuum is created within the ear canal
Solution Approach 1:
The filter assembly uses porous acoustic materials and open-cell foam structures that provide sound attenuation through absorption and scattering rather than complete sealing. This porous approach maintains air permeability while providing effective noise reduction, eliminating the vacuum sensation caused by airtight membranes.
Solution Approach 2:
The filter assembly acts as an intermediary between the external environment and the ear canal, providing sound attenuation through its acoustic properties rather than through complete physical sealing. This intermediary structure allows air exchange while blocking harmful noise frequencies, resolving the comfort issue.
4Adaptability or versatility
If adjustable attenuation mechanisms are added to earplugs, then selective sound control is improved, but device complexity increases
Solution Approach 1:
The rotatable filter assembly provides mechanical adjustability through simple rotation rather than complex electronic or mechanical systems. The rotational degree of freedom allows users to select different attenuation modes by simply turning the filter assembly, providing adaptability with minimal added complexity.
Solution Approach 2:
The earplug achieves multiple attenuation settings by changing the physical orientation parameters of the filter assembly rather than adding multiple separate components. By rotating the assembly to different angular positions, users access different acoustic port configurations, providing versatility through parameter variation rather than structural complexity.
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 earplug provides clear human voice communication in noisy environments and even frequency response across all frequencies in high attenuation mode, ensuring uniform protection and minimal distortion, outperforming prior art in both functionality and sound quality.
Implementation Method 1
an acoustic filter arranged in each of said at least two sound passages. Each acoustic filter comprises an upper acoustic port, at least one acoustic mesh and/or at least one acoustic membrane, an acoustic chamber and a lower acoustic port
Implementation Method 2
Each acoustic filter comprises an upper acoustic port, at least one acoustic mesh and/or at least one acoustic membrane, an acoustic chamber and a lower acoustic port
Data Source
AI summary
An earplug (10, 80) for selective attenuation of sound has a body with at least one sound path. An insert (34) is housed in the body (13), which has at least one sound passage with an acoustic filter. The acoustic filter is configured to provide a specific frequency response and thus a determined attenuation of sound passing through the earplug. Means (14) is arranged at a top surface adapted to activate or deactivate the sound path. Each acoustic filter comprises an upper acoustic port (36, 37), at least one acoustic mesh (35) and/or acoustic membrane (37, 39), an acoustic chamber (41, 44) and a lower acoustic port (42, 43). An insert (34) with an acoustic filter for selective attenuation of sound is provided for use in an earplug.