Wearable Device Occlusion Effect Cancellation via Voice Accelerometer
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Solution Overview
Problem
Wearable hearing devices, such as headphones or earbuds, suffer from the occlusion effect, where sound pressure increases inside the ear canal due to body-conducted sound, leading to reduced acoustic transparency, especially in lower frequencies, which existing active noise control systems fail to fully mitigate.
Innovation Solution
A wearable device incorporating a feedforward microphone, a feedback microphone, and a voice accelerometer, with processors that generate an occlusion effect cancellation signal based on an occlusion effect profile, adjusting the signal dynamically using voice accelerometer data to equalize sound pressure levels and provide full transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ear canal is occluded by earbuds to provide noise isolation, then ambient noise is blocked, but sound pressure level increases inside the ear canal causing the occlusion effect
Solution Approach 1:
The system applies preliminary anti-action by using a feedforward microphone to detect ambient noise before it enters the ear canal, then generating an anti-noise signal through digital signal processing that preemptively cancels out the incoming noise, thereby reducing the occlusion effect while maintaining noise isolation
Solution Approach 2:
The system employs feedback control by using a feedback microphone to continuously monitor the sound pressure level inside the ear canal, then adjusting the anti-noise signal in real-time to maintain optimal cancellation of the occlusion effect while preserving ambient noise blocking
2Object-affected harmful factors
If active noise control is used to cancel ambient noise, then noise isolation is improved, but acoustic transparency is reduced due to the occlusion effect
Solution Approach 1:
The system applies dynamics by continuously adapting the digital signal processing parameters based on real-time input from the feedforward and feedback microphones, allowing the noise cancellation to dynamically adjust its strength and frequency response to maintain acoustic transparency while blocking harmful ambient noise
Solution Approach 2:
The system changes parameters by modifying the gain and frequency response of the anti-noise signal generated by the digital signal processor, adjusting these parameters in real-time to optimize both noise isolation and acoustic transparency, preventing the occlusion effect from degrading sound quality
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
The solution effectively reduces the occlusion effect, allowing for enhanced acoustic transparency by equalizing both bone-conducted and ambient sound, providing a natural listening experience similar to not wearing the device.
Implementation Method 1
body-conducted sound that resonates inside the ear canal
Implementation Method 2
a voice accelerometer
Implementation Method 3
microphone inputs are filtered using a digital signal processing engine that generates sound waves
Implementation Method 4
active noise control system that generates noise cancellation signals based on microphone inputs. The sound waves are then superimposed with the primary sound wave within a user's ear
Implementation Method 5
the frequency of the sound is typically seen in the lower frequencies, often below 800 HZ. This effect is commonly known as the Occlusion Effect which is physically caused by sound pressure from body-conducted sound that resonates inside the ear canal
Data Source
AI summary
A wearable device includes a feedforward microphone; a feedback microphone; a voice accelerometer; and one or more processors in communication with the feedforward microphone, the feedback microphone, and the voice accelerometer. The one or more processors may be configured to receive an occlusion effect (“OE”) profile associated with increased sound pressure level within an ear canal; determine an OE gain profile based on the OE profile; receive voice accelerometer data; adjust the OE gain profile based on the voice accelerometer data; generate an OE cancellation signal based on the OE gain profile to equalize the OE profile; receive, from the feedforward microphone, first audio content including external audio; receive, from the feedback microphone, second audio content including audio within the ear canal of a user; and adjust, based on the OE cancellation signal and the received first and second audio content, an audio output.