Headphone Earpiece Insert With Variable Stiffness for Leak-Free Testing
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Solution Overview
Problem
Commercial dummy heads and related fixtures do not accurately emulate how headphones fit on real humans, leading to significant audio leaks and measurement errors, particularly at low frequencies, due to their rigid structure and shape deviations from human heads.
Innovation Solution
An apparatus with an insert for a headphone earpiece that includes fluid pockets filled with non-Newtonian fluid, providing variable stiffness based on applied force, attached to a head-shaped fixture that mimics human head contours, using a combination of materials and design features to enhance fitting accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid dummy head structure is used, then the fixture provides structural stability, but the headphones do not settle fully on the fixture resulting in large audio leaks and measurement errors
Solution Approach 1:
The patent changes the physical state parameters of the insert material from rigid to viscoelastic, allowing it to deform and conform to the headphone shape. This parameter change enables the insert to adapt to different headphone geometries while maintaining measurement accuracy, resolving the contradiction between structural stability and measurement precision.
Solution Approach 2:
The patent uses composite material construction with an outer shell and an inner viscoelastic core. This composite structure provides both the structural stability of the rigid outer shell and the conforming properties of the soft inner material, simultaneously addressing both requirements.
2Ease of manufacture
If a rigid dummy head is used, then manufacturing and handling is simplified, but the dummy head does not accurately emulate human head contours leading to significant audio leaks
Solution Approach 1:
The insert material parameters are changed to include viscoelastic properties that allow the material to flow and conform to the headphone shape under applied pressure. This enables accurate emulation of human ear contours without complex manufacturing processes, reducing audio leakage while maintaining manufacturing simplicity.
Solution Approach 2:
The patent employs a flexible viscoelastic insert that can deform to match the headphone geometry. This flexible material acts as a conforming interface between the rigid dummy head and the headphone, eliminating gaps that cause audio leakage while keeping the overall structure manufacturable.
3Shape
If a rigid fixture is used, then the fixture maintains its shape, but the headphones do not settle fully resulting in variability in low frequency response measurements
Solution Approach 1:
The insert material transitions from a rigid state to a viscoelastic state, enabling it to adapt its shape to match each headphone while maintaining overall structural integrity. This parameter change ensures consistent measurement conditions across different headphones, improving measurement reliability without compromising shape consistency.
Solution Approach 2:
The patent introduces dynamic properties to the insert through viscoelastic materials that can adjust their stiffness and conformability in response to applied forces. This dynamic behavior allows the insert to optimize its shape-matching capability for each measurement while maintaining stable overall dimensions, thereby improving measurement repeatability.
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 insert with fluid pockets and non-Newtonian fluid improves headphone fitting accuracy, reducing leakage and variability in low-frequency response measurements, thereby enhancing measurement precision.
Implementation Method 1
The fluid is a non-Newtonian fluid
Implementation Method 2
The fluid within the at least one fluid pocket is configured to impart a stiffness that varies based on a force applied to the outer side of the insert by the earpiece
Data Source
AI summary
An apparatus for testing an earpiece of a headphone includes an insert configured to be connected to a head-shaped fixture. The insert has an inner side and an outer side that is opposite the inner side. The outer side is configured to engage the earpiece. The insert defines at least one fluid pocket. The fluid pocket is located between the inner side and the outer side and has a fluid sealed therein. The fluid within the fluid pocket is configured to impart a stiffness that varies based on a force applied to the outer side of the insert by the earpiece.