Adaptive Noise Cancellation with Transient Detection

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Solution Overview

Problem

Conventional adaptive noise cancellation systems in headphones and personal listening devices fail to completely cancel noise, leading to residual noise and audible artefacts due to constructive interference and transient noise events.

Innovation Solution

The adaptive noise cancellation system includes a reference sensor, error sensor, noise cancellation filter, adaptation module, and transient activity detection module to generate and adjust anti-noise signals, reducing noise amplification and artefacts through noise shaping filters and adaptive gain control, and detecting transient noise events to control adaptation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adaptive noise cancellation systems continuously adapt the anti-noise signal to improve noise cancellation, then noise cancellation performance is improved, but transient noise events cause noise amplification and audible artefacts

Engineering Contradiction:

Improvenoise cancellation performanceVSAvoidnoise amplification and audible artefacts

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The transient activity detection module continuously monitors the reference signal and detects transient noise events before they can cause harmful noise amplification. By detecting transients in advance and preemptively disabling adaptation during these events, the system prevents the harmful effects of transient noise before they occur, while maintaining continuous adaptation during normal conditions for optimal noise cancellation performance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the reference signal from the reference sensor as feedback to continuously monitor for transient noise events. This feedback mechanism allows the transient activity detection module to detect changes in the noise environment and control the adaptation module accordingly, disabling it during transient events to prevent noise amplification while enabling it during stable conditions for effective noise cancellation

Inventive Principle:

Principle #23Feedback

2Reliability

If the adaptation module continuously adjusts the anti-noise signal to improve cancellation, then noise cancellation effectiveness is improved, but transient noise events disrupt adaptation causing residual noise

Engineering Contradiction:

Improvenoise cancellation effectivenessVSAvoidresidual noise

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The transient activity detection module continuously monitors the reference signal and detects transient noise events before they can disrupt the adaptation process. By preemptively disabling the adaptation module during detected transient events, the system prevents disruption and residual noise, while maintaining continuous adaptation during normal conditions for optimal noise cancellation effectiveness

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from the reference signal to continuously monitor for transient noise events. This feedback allows the transient activity detection module to detect transient conditions and control the adaptation module accordingly, preventing disruption during transients while maintaining continuous adaptation during stable conditions

Inventive Principle:

Principle #23Feedback

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 system provides robust noise cancellation with reduced artefacts and improved performance across various environments and devices, effectively minimizing noise amplification and transient disruptions.

Implementation Method 1

a reference sensor operable to sense environmental noise and generate a corresponding reference signal

Methodology Applied

Scientific EffectAcoustic transduction:

Implementation Method 2

an error sensor operable to sense noise in a noise cancellation zone and generate a corresponding error signal

Methodology Applied

Scientific EffectAcoustic transduction:

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

Methodology Applied

Scientific EffectSignal filtering and phase inversion:

Implementation Method 4

The noise and anti-noise signal cancel each other acoustically, allowing the user to hear only a desired audio signal

Methodology Applied

Scientific EffectAcoustic interference: Interference

Data Source

PatentUS11049487B2Robust adaptive noise cancelling systems and methods

Publication Date: 2021.06.29 GOOGLE LLC

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, and a transient activity detection module operable to receive the reference signal, detect a transient noise event and selectively disable the adaptation module during the detected transient noise event.