Earmuff Low-Frequency Resonator for Noise Insulation

Solution Overview

Problem

Traditional protective earmuffs provide effective high-frequency noise insulation but are bulky, uncomfortable, and cause noise amplification and fatigue due to their thick design, leading to potential hearing damage.

Innovation Solution

Incorporating a low-frequency resonator in the earmuff cavity to absorb low-frequency noise energy, reducing the earmuff's size and weight while improving noise insulation by adjusting the resonance frequency to match the corner frequency of the low-pass filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thick earmuff shell and large earmuff cavity are used to improve low-frequency noise insulation, then noise insulation performance is improved, but the earmuff becomes bulky, heavy, and uncomfortable to wear

Engineering Contradiction:

Improvenoise insulation performanceVSAvoidwearing comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The earmuff cavity is divided into two independent chambers: a first chamber for high-frequency noise insulation and a second chamber for low-frequency noise insulation. This segmentation allows each chamber to be optimized for its specific frequency range, avoiding the need for a uniformly thick shell while achieving comprehensive noise protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the earmuff are designed with different acoustic properties. The first chamber has specific acoustic impedance for high-frequency attenuation, while the second chamber has different acoustic impedance for low-frequency attenuation. This local optimization allows effective noise insulation without increasing overall earmuff size and weight.

Inventive Principle:

Principle #3Local quality

2Reliability

If a thick earmuff shell is used to lower the corner frequency of the low-pass filter, then more frequency bands are filtered out, but the earmuff becomes bulky and heavy

Engineering Contradiction:

Improvenoise insulation performanceVSAvoidearmuff weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The earmuff cavity is divided into two independent chambers: a first chamber for high-frequency noise insulation and a second chamber for low-frequency noise insulation. This segmentation allows each chamber to be optimized for its specific frequency range, avoiding the need for a uniformly thick shell while achieving comprehensive noise protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The acoustic impedance parameters of the two chambers are differently designed to target specific frequency ranges. By optimizing the acoustic impedance of the second chamber for low-frequency attenuation, the corner frequency can be lowered without increasing the overall earmuff size and weight.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If passive noise insulation is used, then high-frequency noise is effectively blocked, but noise rise and amplification occur at the corner frequency causing fatigue and hearing damage

Engineering Contradiction:

Improvehigh-frequency noise insulationVSAvoidnoise amplification and fatigue

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The earmuff cavity is divided into two independent chambers: a first chamber for high-frequency noise insulation and a second chamber for low-frequency noise insulation. This segmentation allows each chamber to be optimized for its specific frequency range, avoiding the need for a uniformly thick shell while achieving comprehensive noise protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second chamber is designed to exploit the resonance phenomenon at the corner frequency rather than simply blocking it. By carefully designing the acoustic impedance of the second chamber, the resonance is converted into a beneficial low-frequency attenuation mechanism, transforming the harmful noise amplification effect into effective noise reduction.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 low-frequency resonator effectively absorbs noise energy near its resonance frequency, preventing noise rise and amplification, enhancing noise attenuation and wearer comfort without increasing the earmuff's size or weight.

Implementation Method 1

a low-frequency resonator whose resonance frequency is equivalent to a corner frequency of a low-pass filter formed by the earmuff

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

the chamber and the conduit form a low-frequency resonator whose resonance frequency is equivalent to a corner frequency of a low-pass filter formed by the earmuff

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Data Source

PatentUS11141315B2Noise-reducing earmuff

Publication Date: 2021.10.12 GEER TECH CO LTD

AI summary

The present disclosure discloses a noise-reducing earmuff, comprising: an earmuff shell forming an earmuff cavity; a separator being installed in the earmuff cavity and forming an independent chamber; and a conduit being installed on the separator, the conduit being provided with an opening at each of the two ends thereof; wherein one of the openings being located in the chamber, and the other extending out of the chamber and being located in the earmuff cavity; wherein the chamber and the conduit form a low-frequency resonator whose resonance frequency is equivalent to a corner frequency of a low-pass filter formed by the earmuff.