Acoustic Filter Earplug Attenuation Slope
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Solution Overview
Problem
Existing noise protection devices often cause significant frequency distortion, making it difficult to maintain clear sound perception across the entire auditory spectrum, particularly in environments where noise protection is crucial without compromising sound quality, such as in music, airports, and for individuals with hyperacoustia.
Innovation Solution
A noise protection device with a controlled 2 dB/octave slope attenuation response, comprising a cylindrical assembly with a porous acoustic inlet and output parts, a stainless steel grid, and a hyperbolic acoustic cone, designed to provide consistent sound attenuation from 10 to 25 dB across the frequency spectrum, minimizing distortion by amplifying high frequencies and compensating for insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise protection devices are used, then noise attenuation is achieved, but frequency distortion increases
Solution Approach 1:
The acoustic filter is divided into multiple independent porous layers with different porosity values (7-100 μm, 10-50 μm, 5-20 μm). Each layer selectively attenuates specific frequency ranges, allowing the device to achieve broad-spectrum noise attenuation while preserving the proportionality across bass, midrange, and treble frequencies through the controlled 2 dB/octave slope.
Solution Approach 2:
Different regions of the acoustic filter have different porosity characteristics tailored to specific frequency attenuation needs. The gradient in porosity from the acoustic inlet to the acoustic outlet creates the desired 2 dB/octave attenuation slope, with each local region contributing to the overall flat response curve while maintaining noise protection.
2Object-affected harmful factors
If noise attenuation is increased, then protection level improves, but sound perception quality deteriorates
Solution Approach 1:
The device achieves variable attenuation across the frequency spectrum by changing the porosity parameter of the porous layers. The controlled 2 dB/octave slope is realized through systematic variation of porosity values (from 7-100 μm at the inlet to 5-20 μm at the outlet), providing protection levels of 10-25 dB while maintaining a flat response curve that preserves sound perception quality.
3Object-affected harmful factors
If earplug insertion is performed, then noise seal is improved, but insertion loss increases
Solution Approach 1:
The device converts the harmful insertion loss effect into a beneficial controlled attenuation. The earplug insertion naturally causes etymotic effect and amplification in the 3500-4000 Hz range, but the acoustic filter with its specific porosity gradient compensates for this by providing 2 dB/octave attenuation, transforming the insertion-induced frequency distortion into a controlled, beneficial frequency response.
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 device ensures minimal frequency distortion, providing effective noise protection with a flat response curve, allowing users to perceive attenuated sounds without compromising sound quality, particularly in environments requiring broad auditory spectrum protection.
Implementation Method 1
The direction of operation (3. Fig. 2), passes through the porous membrane(s) (M. Fig. 2) effective at attenuating low and porous frequencies (M. Fig. 2) effective at attenuating low and mid-low frequencies
Implementation Method 2
emerges through the hyperbolic acoustic cone (6. Fig. 2) favorable to the amplification of high frequencies in order to compensate for the insertion loss
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device (3. Fig1) to be inserted into an earplug (1. Fig1) previously sealed and the insertion of said device allows the protection of hearing with the perception of attenuated sounds while minimizing the frequency distortion usually inherent in the wearing of noise protection, the response curve of said device is said to be flat or linear with a slope controlled by said device of 2 dB/octave.