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 subdivisions of occluded earbuds are absent, leading to interference between ambient sound and sound produced by the earbuds.
Innovation Solution
The solution involves positioning 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 employing a signal processing circuit to mitigate any residual interference, using both acoustic and electric means to establish isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If open-wear style is adopted to improve comfort and ambient awareness, then wearing comfort and natural sound perception are improved, but isolation between sound producing device and ambient sensing microphone is lost
Solution Approach 1:
The patent introduces a signal processing circuit as an intermediary between the sound producing device and ambient sensing microphone. This circuit processes the signals to separate ambient sound from self-generated sound, effectively creating a virtual isolation layer that maintains ANC functionality without physical barriers.
Solution Approach 2:
The patent replaces the mechanical isolation approach (physical partitions and occluded tips) with an electronic signal processing approach. By using digital signal processing to distinguish and separate sound sources, the system achieves isolation without mechanical barriers, enabling open-wear design while maintaining ANC performance.
2Reliability
If traditional occluded design is used to establish isolation between SPD and ASM, then ANC performance is improved, but wearing comfort and ambient awareness deteriorate
Solution Approach 1:
The patent replaces mechanical isolation structures (ear canal occlusion, housing partitions) with electronic signal processing. The signal processing circuit analyzes sound characteristics to distinguish ambient noise from self-generated sound, achieving isolation through software rather than hardware barriers.
Solution Approach 2:
The patent changes the approach from spatial isolation (physical separation) to parameter-based isolation (signal characteristic differentiation). By analyzing temporal, spectral, and amplitude parameters of sound waves, the system can separate ambient sound from SPD sound without physical separation.
3Ease of operation
If open-wear design is implemented without isolation measures, then comfort is improved, but ANC functionality deteriorates due to sound interference
Solution Approach 1:
The signal processing circuit acts as an intermediary that processes raw microphone signals to extract pure ambient sound information. This intermediary layer enables ANC functionality to operate effectively in open-wear conditions by filtering out self-generated sound interference before ANC processing.
Solution Approach 2:
The patent implements a feedback mechanism where the signal processing circuit continuously monitors and analyzes sound signals, adjusting the separation algorithm based on real-time conditions. This feedback loop ensures consistent ANC performance across varying environmental conditions and user positions.
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 effectively isolates the ambient sensing microphone from the sound produced by the sound producing device, enabling clear ANC and AC performance in open-wear earbuds by minimizing sound leakage and enhancing ambient sound perception.
Implementation Method 1
the diaphragm 142 of the SPD 102 produces a front radiating wave and a back radiating wave while producing the sound
Implementation Method 2
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
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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.