Variable-Stiffness Headphone Measurement Insert for Low-Frequency Leakage
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Solution Overview
Problem
Commercial dummy heads used for headphone measurements do not accurately emulate how headphones fit on real humans, leading to significant errors in low-frequency audio leakage measurements, often exceeding 10 dB from 20 to 500 Hz.
Innovation Solution
An insert for headphone measurements featuring a body with variable stiffness, designed to engage with headphones and include an opening for a pinna, attached to a head-shape fixture via a coupler, allowing for a more accurate representation of human head properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid dummy head fixture is used for headphone measurements, then the structural stability is improved, but the measurement precision deteriorates due to inaccurate emulation of human head properties and large audio leaks
Solution Approach 1:
The patent applies a flexible insert made of elastomeric material that conforms to the curved surface of the headphone cup, creating a seal that prevents audio leakage while maintaining structural stability through the coupler attachment system
Solution Approach 2:
The fixture combines a rigid head-shape structure with a flexible elastomeric insert and foam material, creating a composite system that provides both structural stability and accurate emulation of human head properties for improved measurement precision
2Duration of action of stationary object
If a rigid dummy head is used, then the fixture durability is improved, but the adaptability to different headphone types deteriorates because headphones cannot settle fully on the fixture
Solution Approach 1:
The flexible elastomeric insert can deform to accommodate different headphone shapes and sizes, allowing various headphone types to settle properly on the fixture while the rigid outer structure maintains durability
Solution Approach 2:
The insert transitions from a rigid state to a flexible state during headphone placement, allowing adaptation to different headphone configurations, then maintains a stable sealed state during measurement
3Ease of manufacture
If conventional dummy head materials are used, then the manufacturing simplicity is improved, but the reliability of leakage measurement deteriorates due to large variability in low frequency response
Solution Approach 1:
The elastomeric insert provides consistent sealing properties that reduce variability in leakage measurements, improving reliability while the insert can be manufactured as a separate component and attached to the existing rigid fixture
Solution Approach 2:
The patent changes the material parameter from rigid to flexible elastomeric material for the portion that contacts the headphone, improving sealing consistency and measurement reliability
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 improves the accuracy of headphone leakage measurements by allowing headphones to settle properly on the fixture, reducing variability in low-frequency response and enhancing the regulation of leakage.
Implementation Method 1
The body has a variable stiffness
Implementation Method 2
a portion of the body is made of a silicone rubber gel; the silicone rubber gel has a Shore hardness of about 000-34
Data Source
AI summary
An insert for headphone measurements on a head-shape fixture includes a body and a coupler. The body is configured to engage at least a portion of the headphones. The body also defines an opening that is configured to receive a pinna on the head-shape fixture. The body has a variable stiffness. The coupler attaches the body to the head-shape fixture.