Adaptive Noise Cancellation with Frequency-Region-Specific Control
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Solution Overview
Problem
Conventional adaptive noise cancellation systems in headphones and earbuds fail to completely cancel noise, leading to residual noise and audible artefacts due to constructive interference and transient noise events, which affect user experience.
Innovation Solution
The adaptive noise cancellation system incorporates a reference sensor, error sensor, noise cancellation filter, and an adaptation module with noise amplification control and transient activity detection to adjust the anti-noise signal, minimizing noise amplification and artefacts by using a noise-shaping filter and adaptive gain control, and detecting transient noise events to prevent disruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If adaptive noise cancellation is implemented to cancel environmental noise, then noise cancellation performance is improved, but noise amplification and audible artefacts occur in certain frequency regions
Solution Approach 1:
The patent applies local quality by implementing frequency-region-specific processing in the adaptation module. Different adaptation algorithms are applied to different frequency regions: a first adaptation algorithm is used for non-hiss regions while a second adaptation algorithm is used for hiss regions. This localized approach allows the system to optimize noise cancellation in each frequency region independently, preventing noise amplification in specific bands while maintaining overall cancellation performance.
Solution Approach 2:
The patent segments the frequency spectrum into distinct regions (hiss regions and non-hiss regions) and processes each region separately. The adaptation module divides the frequency domain into multiple bands and applies different adaptation strategies to each band. This segmentation allows the system to identify and suppress noise amplification in problematic frequency regions while maintaining effective cancellation in other regions.
2Object-affected harmful factors
If conventional adaptive filtering is used to generate anti-noise signal, then noise cancellation is achieved, but residual noise and artefacts remain due to incomplete cancellation
Solution Approach 1:
The patent implements feedback by using an error microphone to continuously monitor the noise cancellation zone and feed the error signal back to the adaptation module. The error signal represents the residual noise and artefacts after initial cancellation. The adaptation module processes this feedback signal and adjusts the anti-noise signal accordingly, continuously improving cancellation performance and reducing residual noise through iterative refinement.
Solution Approach 2:
The patent applies dynamics by making the adaptation module continuously adjustable and responsive to changing noise conditions. The system dynamically adapts to different environmental noise profiles, transient noise events, and frequency-specific characteristics. The adaptation parameters are continuously updated based on real-time error signal analysis, allowing the system to maintain optimal performance across varying conditions rather than using fixed filtering parameters.
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 approach provides improved hiss control and suppression, reducing perceptible noise amplification and artefacts, ensuring robust noise cancellation across various environments and user conditions, while maintaining effective cancellation performance and reducing computational complexity.
Implementation Method 1
a reference sensor operable to sense environmental noise and generate a corresponding reference signal
Implementation Method 2
an error sensor operable to sense noise in a noise cancellation zone and generate a corresponding error signal
Implementation Method 3
a noise cancellation filter operable to receive the reference signal and generate an anti-noise signal to cancel the environmental noise in the cancellation zone
Implementation Method 4
an adaptation module operable to receive the reference signal and the error signal and adaptively adjust the anti-noise signal
Data Source
AI summary
Adaptive noise cancellation systems and methods comprise a reference sensor operable to sense environmental noise and generate a corresponding reference signal, an error sensor operable to sense noise in a noise cancellation zone and generate a corresponding error signal, a noise cancellation filter operable to receive the reference signal and generate an anti-noise signal to cancel the environmental noise in the cancellation zone, an adaptation module operable to receive the reference signal and the error signal and adaptively adjust the anti-noise signal.