Feedforward Microphone Placement for Earbud Noise Coherence
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Solution Overview
Problem
Existing active noise reduction (ANR) earbuds struggle with low coherence at higher frequencies due to feedforward microphones being spaced from the ear canal, making them ineffective in sensing noise through the ear tip and body tissue.
Innovation Solution
Placing a feed-forward microphone close to the ear tip, ideally in the concha, allows it to sense noise in the dominant noise path through the ear tip and body tissue, enhancing coherence by enabling effective noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the feedforward microphone is placed away from the ear canal, then the device structure is simpler and easier to manufacture, but the coherence at higher frequencies deteriorates
Solution Approach 1:
The patent utilizes the spatial dimension by positioning the feedforward microphone in the concha (outer ear) rather than inside the ear canal, changing the detection location to a different anatomical dimension. This allows the microphone to capture noise through the ear tip and body tissue path, improving coherence at higher frequencies while maintaining manufacturing simplicity
Solution Approach 2:
The ear tip and body tissue act as an intermediary medium that transmits noise from the external environment to the feedforward microphone located in the concha. This natural tissue path serves as the measurement medium, enabling effective noise sensing without requiring the microphone to be inserted into the ear canal
2Measurement precision
If the feedforward microphone is placed close to the ear tip, then the coherence at higher frequencies is improved, but the device complexity increases
Solution Approach 1:
The concha location serves multiple functions: it is the natural outer ear structure that already exists in the human anatomy, it provides access to the dominant noise path through ear tip and tissue, and it allows for simplified microphone positioning without requiring additional components or complex assembly procedures
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 coherence of the ANR system, particularly at higher frequencies, by effectively sensing and canceling noise through the dominant noise paths, leading to better noise reduction performance.
Implementation Method 1
a first feedforward microphone configured to sense external sound that is conducted through a first sound inlet opening in the housing that is proximate the outlet portion
Data Source
AI summary
An active noise reduction earbud includes a housing and a first feedforward microphone disposed in the housing. A first sound inlet opening extends through the housing and is configured to conduct external sound to the first feedforward microphone. The first sound inlet opening is configured to sit within a concha cavum of a user's ear and faces toward an auricle of the user's ear when the earbud is worn.