Headphone Reference Microphones for Directional Noise Pickup
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Solution Overview
Problem
Conventional headphones with single centrally located reference microphones for ANC and transparency suffer from directionality issues and noise interference, particularly with strong passive sound isolation, leading to suboptimal performance in picking up directional ambient noise and handling wind and scratch noise.
Innovation Solution
The use of multiple reference microphones positioned along the perimeter of the ear cup housing, with an error microphone and a processor that drives the speaker for ANC and transparency, and performs oversight processes to adjust microphone signals in response to wind and scratch events, ensuring effective noise cancellation and ambient sound reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single centrally located reference microphone is used for ANC and transparency, then the device complexity is reduced, but the measurement precision of directional ambient noise deteriorates
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 noise from different directions, improving the system's ability to detect and cancel directional noise sources while maintaining manageable device complexity through modular signal processing.
Solution Approach 2:
The microphone arrangement transitions from a single-point (0D) or central location to a distributed spatial configuration (3D) on the ear cup housing. This dimensional expansion enables the system to capture spatial information about ambient noise, improving directional accuracy and measurement precision without significantly increasing overall system complexity.
2Measurement precision
If multiple reference microphones are used to improve directional sound pickup, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Multiple reference microphones are merged into a unified signal processing framework where their outputs are combined through digital signal processing algorithms. This merging approach allows the system to leverage the spatial diversity of multiple microphones for improved directional accuracy while managing complexity through integrated processing rather than separate handling of each microphone.
Solution Approach 2:
The multiple reference microphones serve multiple functions simultaneously: they provide reference signals for ANC, reference signals for transparency mode, and spatial information for directional noise identification. This multi-functionality maximizes the utility of each additional microphone, improving measurement precision without proportionally increasing overall system complexity.
3Measurement precision
If reference microphones are positioned on the perimeter of the ear cup housing, then the directional sound pickup improves, but the ease of manufacture deteriorates
Solution Approach 1:
The microphone positioning adopts an asymmetric perimeter distribution rather than symmetric central placement, optimizing directional sound pickup by strategically locating microphones at positions that maximize spatial coverage. This asymmetric arrangement improves measurement precision while the positions can be predetermined in the design phase, allowing for standardized manufacturing processes despite the non-central locations.
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 enhances ANC and transparency performance by improving sound pickup of directional sources, mitigating wind and scratch noise, and maintaining consistent ambient sound reproduction, even in windy environments.
Implementation Method 1
several reference microphones picking up the ambient sound including sound from directional sources
Implementation Method 2
drive a speaker of the headphone to generate a sound field that is electronically designed to destructively interfere with the leaked ambient sound
Implementation Method 3
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
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.