Headphone Ear Cushion Asymmetric Transducer Orientation
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Solution Overview
Problem
Circum-aural headphones face issues with sound reflections and frequency response anomalies, particularly at high frequencies above 1 kHz, due to design limitations in the ear cushion and transducer configuration, leading to uneven sound quality and noise isolation.
Innovation Solution
The design incorporates an annular ear cushion with a compliant material and a sound-absorbing sheet over the baffle surface, oriented non-parallel to the contact surface, along with a transducer positioned asymmetrically to reduce reflections, using materials like memory foam and sound-absorbing foam to enhance acoustic sealing and frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the transducer is positioned parallel to the contact surface of the ear cushion, then the structure is simpler and easier to manufacture, but sound reflections increase and frequency response becomes uneven at high frequencies
Solution Approach 1:
The patent positions the transducer asymmetrically relative to the ear cushion contact surface, specifically orienting the transducer parallel to the user's pinna rather than parallel to the contact surface. This asymmetric positioning reduces sound reflections and improves frequency response consistency, particularly at high frequencies above 1 kHz, while maintaining manufacturing feasibility through the defined geometric relationships between components.
2Volume of stationary object
If the baffle surface is oriented parallel to the contact surface, then the acoustic chamber volume is maximized, but sound reflections and frequency response anomalies occur at high frequencies
Solution Approach 1:
The baffle surface is oriented at an angle relative to the contact surface rather than being parallel, creating an asymmetric acoustic chamber configuration. This angular orientation positions the transducer parallel to the user's pinna, which reduces sound reflections and eliminates frequency response anomalies above 1 kHz while preserving adequate acoustic chamber volume for effective noise isolation.
3Device complexity
If standard ear cushion materials are used without additional sound absorbent materials, then the device complexity is reduced, but frequency response consistency and noise isolation performance are insufficient
Solution Approach 1:
The patent incorporates a sound absorbent material layer within the ear cushion structure, specifically positioning it to address local acoustic issues within the acoustic chamber. This localized addition of sound-absorbing properties improves frequency response consistency and noise isolation performance without significantly increasing overall device complexity, as the material is integrated into the existing ear cushion geometry.
4Ease of manufacture
If the ear cushion is designed with a simple annular shape, then manufacturing is easier, but acoustic sealing and noise isolation performance are insufficient
Solution Approach 1:
The ear cushion maintains its simple annular shape for ease of manufacture, but incorporates a sound absorbent material layer with specific acoustic properties to enhance noise isolation performance. The sound absorbent material is positioned within the acoustic chamber to locally improve acoustic sealing and attenuation without requiring complex geometric modifications to the ear cushion structure itself.
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 results in improved frequency response consistency and extended sound quality, reducing unwanted reflections and noise isolation issues, with over 20dB attenuation at 1 kHz and smooth frequency response across the audible band.
Implementation Method 1
The sheet is formed of a sound absorbent material to suppress sound reflections within an acoustic chamber defined by the sheet, the ear cushion, and the user's head
Implementation Method 2
an ear cushion for coupling the headphone transducer to the ear of a user, while providing an acoustic seal to form an acoustic pressure chamber
Data Source
Figure 1~2
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Figure 5~6
AI summary
A headphone is provided with a housing and a transducer. The housing has a baffle surface with a recess formed therein and an edge formed about a periphery of the baffle surface. The transducer disposed in the recess and supported by the housing. The headphone is also provided with an ear cushion and a sheet. The ear cushion has a base formed in an annular shape and connected to the housing about the edge and a contact surface spaced apart from the base to engage a portion of a user's head around an outer ear, wherein the ear cushion defines a cavity to collectively form an acoustic chamber with the user's head. The sheet is disposed over the baffle surface with a hole formed therethrough and aligned with the transducer. The sheet is also formed of a sound absorbent material to suppress sound reflections within the acoustic chamber.