Earphone Nozzle Composite Metal Structure Vibration Damping
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Solution Overview
Problem
Canal earphones face challenges in achieving high sound pressure levels and expanded frequency bands for improved sound reproduction due to small speaker units and housing constraints, leading to suboptimal sound quality and manufacturing costs.
Innovation Solution
The earphone design incorporates a nozzle portion with a base member made of one metal material and a tubular member made of a different metal material, bonded together with an adhesive layer, forming an acoustic path that reduces vibration and sound distortion, using materials like aluminum alloy and brass to minimize noise from housing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small speaker unit is used in the canal earphone housing, then the earphone can be compact and fit in the ear canal, but the sound pressure level is insufficient and the frequency band expansion is limited
Solution Approach 1:
The housing is segmented into multiple functional parts: a main body housing containing the speaker unit, and a separate nozzle portion that extends into the ear canal. This segmentation allows the speaker unit to remain small while the nozzle amplifies and directs sound waves efficiently into the ear canal, resolving the contradiction between compact size and sufficient sound pressure level.
Solution Approach 2:
The nozzle portion extends the sound transmission path into the ear canal dimension, creating a focused acoustic channel. This dimensional extension allows a small speaker unit to generate adequate sound pressure by concentrating acoustic energy along the nozzle's length, rather than relying solely on speaker unit size.
2Volume of moving object
If a small speaker unit is used in the canal earphone housing, then the earphone can be compact, but the sound reproduction frequency band is limited
Solution Approach 1:
The housing is segmented into multiple functional parts: a main body housing containing the speaker unit, and a separate nozzle portion that extends into the ear canal. This segmentation allows the speaker unit to remain small while the nozzle amplifies and directs sound waves efficiently into the ear canal, resolving the contradiction between compact size and sufficient sound pressure level.
Solution Approach 2:
The nozzle portion's geometric parameters (length, diameter, taper angle) are optimized to enhance frequency response. By carefully controlling these parameters, the nozzle acts as an acoustic transformer that expands the effective frequency band of the small speaker unit, maintaining sound reproduction quality despite the compact size.
3Ease of manufacture
If a single metal material is used for the nozzle portion, then the manufacturing is simple and cost is low, but the housing vibrations cause noise and degrade sound quality
Solution Approach 1:
The nozzle portion is constructed as a composite structure with an inner wall made of a first metal material and an outer wall made of a second metal material with different vibration characteristics. This composite construction dampens housing vibrations through material mismatch, reducing vibration-induced noise while maintaining manufacturing feasibility through sequential fabrication processes.
4Object-generated harmful factors
If the nozzle portion is made with multiple metal materials, then the vibration noise is reduced, but the manufacturing complexity and cost increase
Solution Approach 1:
The nozzle portion is constructed as a composite structure with an inner wall made of a first metal material and an outer wall made of a second metal material with different vibration characteristics. This composite construction dampens housing vibrations through material mismatch, reducing vibration-induced noise while maintaining manufacturing feasibility through sequential fabrication processes.
Solution Approach 2:
Different metal materials are applied locally to specific regions of the nozzle portion - the inner wall uses one material optimized for acoustic properties while the outer wall uses another material optimized for vibration damping. This localized material differentiation reduces overall complexity compared to using multiple materials throughout the entire structure.
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
This configuration enhances sound quality by reducing noise from housing vibrations and lowers manufacturing costs while maintaining natural sound reproduction.
Implementation Method 1
The inner wall surface of the base member and the outer wall surface of the tubular member are fixed together through an adhesive layer
Implementation Method 2
a nozzle portion forming an acoustic path communicating with the acoustic space to guide the sound wave to an ear canal of a user
Data Source
Figure 1~2
Figure 3(a)~4
AI summary
The earphone is an earphone including a speaker unit configured to electroacoustically transduce an audio signal into a sound wave, and a housing configured to define an acoustic space on at least one side of a diaphragm of the speaker unit, the speaker unit being attached to the inside of the housing. The housing includes a nozzle portion forming an acoustic path communicating with the acoustic space to guide the sound wave to the ear canal of the user. The nozzle portion includes a base member made of a first metal material and defining an outer shell of the nozzle portion, and a tubular member of which outer wall surface is fixed to an inner wall surface of the base member to form the acoustic path on the inside and which is made of a second metal material different from the first metal material.