Earbud Sound Port Microphone Placement for ANC
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Solution Overview
Problem
Active noise cancellation (ANC) performance in earbud devices is limited due to factors like the form factor, microphone and speaker positioning, and fit, which result in suboptimal noise cancellation, especially in lower frequency ranges and higher frequencies, leading to residual noise and bandwidth limitations.
Innovation Solution
The placement of an internal microphone within the sound port of the earbud, closer to the ear canal, allows it to sense noise more accurately, combined with a secondary path for anti-noise signal propagation, enhancing noise cancellation by improving the alignment of noise and anti-noise signals at the user's eardrum, and using a hybrid feedforward-feedback ANC system to process error signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the earbud uses a compact form factor to fit in the outer concha, then it can be worn comfortably, but the available space for optimal microphone and speaker positioning is limited, reducing ANC performance
Solution Approach 1:
The patent positions the internal microphone at the distal end of the sound port, extending it along the acoustic path dimension rather than placing it conventionally near the speaker. This dimensional repositioning allows the microphone to capture noise closer to the ear canal entrance while maintaining the compact earbud form factor, thereby improving ANC performance without compromising wearability
2Device complexity
If the internal microphone is positioned closer to the speaker, then the device structure is simpler, but the microphone cannot accurately sense external noise propagating through the ear canal, reducing noise cancellation accuracy
Solution Approach 1:
The sound port acts as an acoustic intermediary channel that guides external noise from the ear canal entrance to the internal microphone positioned at its distal end. This intermediary structure enables the microphone to sense noise accurately without requiring direct exposure to the ear canal environment, maintaining both measurement precision and device simplicity
3Reliability
If the earbud design accommodates optimal microphone placement for ANC, then noise cancellation improves, but the device size and complexity increase
Solution Approach 1:
The sound port is designed to serve multiple functions: it acts as the acoustic passage for sound output from the speaker, the sensing channel for the internal microphone to detect external noise, and the structural element that defines the earbud's interface with the ear canal. This multi-functionality allows optimal microphone placement for ANC without increasing overall device volume
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 achieves deeper and wider-range noise cancellation, particularly in higher frequencies, by aligning noise and anti-noise signals at the eardrum, reducing residual noise and improving the overall ANC performance.
Implementation Method 1
a first microphone disposed within the sound port at the second end of the sound port such that the first microphone is configured to detect the anti-noise signal that propagates through the sound port via the secondary path and the external noise that propagates via a primary path
Implementation Method 2
sound waves emitted from the speaker propagates via a secondary path to the ear canal through the sound port
Data Source
AI summary
Systems and methods for audio listening devices, comprise a speaker coupled to a first housing, a sound port having a first end and a second end, wherein the first end is coupled to the first housing, and the second end is configured to be inserted in an ear canal of a person such that sound waves emitted from the speaker propagates via a secondary path to the ear canal through the sound port, active noise cancellation (ANC) components configured to generate anti-noise signals through the micro-speakers to cancel external noise, and a first microphone disposed within the sound port at the second end of the sound port such that the first microphone is configured to detect the anti-noise signal that propagates through the sound port via the secondary path and the external noise that propagates via a primary path.