Open-Wear Earbud Microphone Placement for ANC Isolation
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Solution Overview
Problem
Open-wear style true wireless earbuds lack the isolation between the sound producing device (SPD) and ambient sensing microphone (ASM) necessary for effective Active Noise Cancellation (ANC) and ambient control (AC), as the traditional subdivision of spaces in occluded earbuds is absent, leading to interference between ambient sound and sound produced by the earbuds.
Innovation Solution
The solution involves placing the ambient sensing microphone on a nodal position where the front and back radiating waves from the sound producing device cancel each other out acoustically, and using a signal processing circuit to mitigate sound signal components from the sensed signal, ensuring a cleaned ambient signal is produced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open-wear style is used to improve comfort and ambient awareness, then user comfort and natural sound perception are improved, but isolation between SPD and ASM is lost causing interference
Solution Approach 1:
The patent divides the earbud housing into distinct front and back chambers separated by a partition wall. The sound producing device is placed in the back chamber while the ambient sensing microphone is positioned in the front chamber, creating spatial segmentation that isolates the microphone from direct sound produced by the speaker, thereby resolving the interference issue while maintaining open-wear comfort
Solution Approach 2:
The patent introduces a partition wall as an intermediary structure between the sound producing device and the ambient sensing microphone. This partition wall acts as a physical barrier that blocks direct sound transmission from the SPD to the ASM, enabling the microphone to sense only ambient sounds without interference from the earbud's own sound output
2Reliability
If traditional occluded design is used to achieve isolation, then ANC effectiveness is improved, but comfort and ambient awareness deteriorate
Solution Approach 1:
The patent segments the internal space into front and back chambers with a partition wall, allowing the ASM to be isolated from SPD acoustically while the open-wear design maintains user comfort. This segmentation enables ANC functionality without requiring occlusion
Solution Approach 2:
The patent replaces the mechanical occlusion system (silicone/foam tips blocking the ear canal) with an acoustic isolation system using a partition wall and strategic component placement. This substitution maintains the isolation needed for ANC while eliminating the discomfort of occlusion
3Volume of moving object
If SPD and ASM are placed close together to reduce device size, then compactness is improved, but sound interference increases
Solution Approach 1:
The patent divides the compact earbud housing into front and back chambers using a partition wall, allowing close placement of SPD and ASM while maintaining acoustic isolation. This segmentation enables miniaturization without sacrificing interference rejection
Solution Approach 2:
The patent applies local acoustic isolation using a partition wall specifically at the interface between the SPD and ASM regions. This localized quality control provides sound interference protection precisely where needed while maintaining overall device compactness
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 approach reestablishes the isolation between SPD and ASM, enabling effective ANC and AC in open-wear earbuds by minimizing sound interference, allowing for clearer music or voice perception without ambient disturbances.
Implementation Method 1
The sound producing device produces a front radiating wave and a back radiating wave while producing the sound. The sound sensing device is disposed on a nodal position where the front radiating wave and the back radiating wave cancel each other on the nodal position.
Data Source
AI summary
The wearable device includes a sound producing device and a sound sensing device. The sound producing device produces a front radiating wave and a back radiating wave while producing the sound. The sound sensing device is disposed on a nodal position where the front radiating wave and the back radiating wave cancel each other on the nodal position.