Earbud Membrane Acoustic Mass Loading Bass Response
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Solution Overview
Problem
The existing design of earbuds with acoustic bass tuning tubes takes up too much space, which can be a limitation in achieving improved bass response due to the need for a separate back volume and bass tube.
Innovation Solution
A membrane is used to provide equivalent acoustic mass loading to the driver, eliminating the need for a bass tube by being part of the back volume chamber and engineered for specific vibration responses, with one side inside the chamber and the other open to the atmosphere, potentially covered by an acoustically transparent mesh.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bass tuning tube is added to improve bass response, then the acoustic mass loading is increased and bass response is extended, but the device occupies too much space
Solution Approach 1:
The membrane is integrated into the back volume chamber wall structure, merging the acoustic mass loading function with the existing housing. This eliminates the need for a separate bass tuning tube while maintaining the acoustic mass loading effect, thereby extending bass response without occupying additional space.
Solution Approach 2:
The membrane serves multiple functions: it provides acoustic mass loading for bass enhancement, acts as part of the back volume chamber structure, and can be positioned to manage acoustic leakage. This multi-functionality replaces the dedicated bass tuning tube, achieving bass improvement without increasing device volume.
2Reliability
If the back volume chamber is made larger to improve bass response, then the acoustic mass loading is increased, but the earbud housing becomes bulkier
Solution Approach 1:
A flexible membrane is used instead of a rigid expansion of the back volume chamber. The membrane provides the necessary acoustic compliance and mass loading effect with minimal space requirement, as it is a thin film that can be integrated into the existing housing structure without increasing overall housing volume.
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 solution allows for a lower-profile earbud design while maintaining or enhancing bass response by achieving equivalent acoustic mass loading without the need for additional space-consuming components, as shown in the acoustic response curves.
Implementation Method 1
The membrane should be engineered in terms of its composition, elasticity, and size so as to exhibit a desired vibration response (to the sound waves emanating from the rear face of the diaphragm) in order to achieve a desired equivalent acoustic mass loading against the diaphragm such that the bass region of the earbud's acoustic response is extended.
Implementation Method 2
The membrane should be engineered in terms of its composition, elasticity, and size so as to exhibit a desired vibration response
Implementation Method 3
The opening may be as large as the area of the membrane. The vent hole, air passage or larger opening may be covered by an acoustically transparent protective mesh (so as to physically protect the otherwise exposed membrane).
Data Source
AI summary
An in-ear earphone housing has a speaker driver installed therein. The driver has a diaphragm with a front face and a rear face, and a motor to vibrate the diaphragm in accordance with an audio signal. A back volume chamber is positioned behind the driver within the earphone housing. The diaphragm is part of a wall of the back volume chamber. An acoustic mass loading membrane that is part of a wall of the back volume chamber, and that is to vibrate in response to acoustic waves produced by vibration of the diaphragm impinging on a front face of the membrane, is provided. Other embodiments are also described and claimed, including a polymer production process for an elastic material.