Multiple Reference Microphones for ANC Wind Noise Mitigation
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Solution Overview
Problem
Conventional headphones with single centrally located reference microphones for ANC and transparency functions face directionality issues and noise interference, leading to suboptimal performance in canceling ambient noise and reproducing ambient sounds, especially in windy or scratch-prone environments.
Innovation Solution
The use of multiple reference microphones positioned along the perimeter of the ear cup housing, with an oversight process that adjusts microphone signals in real-time to mitigate wind, scratch, and ultrasonic noise, enhances the ANC and transparency functions by improving sound pickup and noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single centrally located reference microphone is used for ANC and transparency functions, then the device complexity is reduced, but the measurement precision and noise cancellation performance deteriorate due to directionality issues and noise interference
Solution Approach 1:
The single reference microphone is segmented into multiple reference microphones positioned at different locations on the ear cup housing. This segmentation allows each microphone to capture ambient sound from different directions, improving the overall measurement precision and noise cancellation performance by providing diverse spatial information.
Solution Approach 2:
The microphone arrangement transitions from a single-point (0D) or central location to a distributed spatial arrangement (3D) on the ear cup housing. This dimensional change enables the system to capture ambient sound from multiple directions simultaneously, resolving the directionality issues inherent in single-microphone configurations.
2Reliability
If multiple reference microphones are positioned along the perimeter of the ear cup housing, then the noise cancellation performance improves, but the device complexity increases
Solution Approach 1:
Different reference microphones are positioned at specific locations on the ear cup housing to capture ambient sound from different directions. Each microphone is strategically placed to optimize its ability to pick up sound from particular areas, creating local quality variations that collectively improve overall noise cancellation effectiveness.
3Measurement precision
If reference microphones are used in windy or scratch-prone environments, then ambient sound pickup is improved, but wind noise and scratch interference increase
Solution Approach 1:
The system uses feedback mechanisms to monitor the signals from multiple reference microphones and automatically adjust processing parameters to mitigate wind noise and scratch interference. The processor analyzes the incoming signals and applies appropriate filtering or gain adjustments to maintain measurement precision while reducing the impact of harmful environmental factors.
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 configuration improves the headphones' ability to effectively cancel ambient noise and reproduce ambient sounds, maintaining clarity and reducing unwanted noise interference, even in challenging environments.
Implementation Method 1
drive a speaker of the headphone to generate a sound field that is electronically designed to destructively interfere with the leaked ambient sound, in order to create a quiet region at the wearers ear drum
Implementation Method 2
drive the speaker for transparency (to reproduce ambient sounds), by processing the reference microphone signals
Data Source
AI summary
An ear cup housing has several reference microphones, an error microphone and a speaker. A processor drives the speaker for acoustic noise cancellation and transparency, by processing the microphone signals, and performs an oversight process by adjusting the reference microphone signals in response to detecting wind noise events and scratch events. In another aspect, the ear cup housing has an outside face that is joined to an inside face by a perimeter and the reference microphones are on the perimeter. Other aspects are also described and claimed.