Hearing Protector Sound Damping Filter Resonance Compensation
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Solution Overview
Problem
Conventional hearing protectors fail to adequately address the resonance frequency issue in the 2.5 - 3.5 kHz range due to the alteration of the auditory duct's resonance characteristics when the protector is placed, leading to inadequate sound damping in this frequency range.
Innovation Solution
A sound damping filter with a sound damping canal comprising a first tube part and a second tube part, where the second tube part is a protrusion with a smaller passage and a membrane, allowing for tailored acoustic resistance to compensate for the lost resonance frequency, with specific dimensions and membrane configurations to achieve a flat damping characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a hearing protector is placed in the auditory duct, then sound protection is provided, but the resonance frequency amplification (10-15dB at 2.5-3.5 kHz) is lost or suppressed
Solution Approach 1:
The sound damping canal is segmented into a first tube part and a second tube part, where the first tube part provides overall sound damping and the second tube part specifically addresses resonance frequency compensation. This segmentation allows independent optimization of each section for different functions.
Solution Approach 2:
The second tube part is designed with specific local characteristics (smaller cross-section, specific length) to create targeted acoustic resistance at the resonance frequency range (2.5-3.5 kHz), while the first tube part handles broader frequency damping. This local quality differentiation enables precise control over frequency-specific sound attenuation.
2Ease of manufacture
If the sound damping canal is designed with uniform cross-section, then manufacturing is simplified, but resonance frequency compensation cannot be achieved
Solution Approach 1:
The sound damping canal transitions from a uniform cross-section design to an asymmetric design where the second tube part has a smaller cross-section than the first tube part. This asymmetric geometry creates the necessary acoustic resistance variation to compensate for resonance frequency amplification while remaining manufacturable through standard molding or fabrication processes.
3Object-affected harmful factors
If the second tube part is made longer, then resonance frequency damping increases, but overall sound transmission is excessively reduced
Solution Approach 1:
The second tube part is designed with a specific optimal length that provides just enough acoustic resistance to compensate for resonance frequency amplification (10-15dB) without excessively reducing overall sound transmission. This partial action approach ensures adequate resonance control while maintaining natural sound perception in other frequency ranges.
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 solution effectively reduces sound amplification in the 2.5 - 3.5 kHz range, providing a more natural sound perception while maintaining reduced overall sound exposure, by compensating for the resonance frequency loss and achieving a tailored acoustic resistance.
Implementation Method 1
said first tube part comprises at least one membrane providing a sound damping function
Implementation Method 2
the second tube part forms a protrusion. That is, it is relatively short compared to the first tube part and the passage through the second tube part is substantially smaller compared to the passage through the first tube part
Implementation Method 3
The length of the auditory duct of a person results in a resonance frequency (1/4 wavelength), which is typically between 2.5 - 3.5 kHz. Sound within this frequency range is amplified by about 10 - 15dB due to the resonant cavity effect
Data Source
Figure 1~2
AI summary
A sound damping filter (1) for a hearing protector placeable in the auditory duct of a person, said sound damping filter comprising a sound damping canal, wherein said sound damping canal comprises a first tube part (3) connected to a second tube part (4), wherein said first tube part provides for a sound inlet opening (2) and wherein said second tube part provides for a sound outlet opening (7) such that a sound passage extends in said sound damping canal from said sound inlet opening to said sound outlet opening, wherein said first tube part comprises at least one membrane (5, 6) providing a sound damping function, and wherein said sound inlet opening is larger than said sound outlet opening.