Feedforward Audio Instability Detection with Phase Verification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Audio systems with feedforward instability, such as headphones and headsets, experience issues due to unintended feedback loops causing instability, which can result in loud audible artifacts like tones or squealing, and existing detection methods are prone to false positives.
Innovation Solution
The system detects feedforward instability by monitoring for tonal signatures in the signal path and adjusts the phase response to confirm the detection, using a phase adjuster to alter the phase shift and verify the presence of instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feedforward microphone picks up acoustic signals from the driver to form a closed loop system, then the system can detect and counteract noise effectively, but the system becomes unstable and produces audible artifacts like tones or squealing
Solution Approach 1:
The patent applies feedback by monitoring the output of the feedforward path and using this information to adjust the system parameters. The instability detection mechanism continuously monitors the feedforward path output and feeds this information back to the processor, which then adjusts the transfer function or gains to maintain stability while preserving noise reduction effectiveness.
Solution Approach 2:
The patent changes system parameters dynamically to resolve the contradiction. When instability is detected through tonal signature analysis, the system modifies parameters such as the transfer function coefficients or gain values in the feedforward path, thereby adjusting the system's stability characteristics while maintaining its noise reduction capability.
2Extent of automation
If existing detection methods are used to detect feedforward instability, then detection can be implemented, but false positives occur reducing detection accuracy
Solution Approach 1:
The patent introduces an intermediary verification mechanism between the initial instability detection and the final instability confirmation. The tonal signature analysis acts as an intermediary that filters out false positives by requiring specific spectral characteristics to be present, thereby improving detection accuracy while maintaining automated operation.
Solution Approach 2:
The patent performs preliminary analysis of the signal characteristics before confirming instability. By analyzing tonal signatures and spectral patterns in advance, the system prepares verification criteria that must be met before declaring instability, reducing false positives while maintaining automated detection capability.
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 effectively confirms the presence of instability and allows for corrective actions, enabling systems to operate closer to instability boundaries, thereby improving performance and doubling the effective noise reduction bandwidth.
Implementation Method 1
an acoustic transducer to convert a third signal, based at least in part upon the second signal, into an acoustic signal
Implementation Method 2
adjusts the phase response to confirm the detection, using a phase adjuster to alter the phase shift and verify the presence of instability
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Audio devices and methods are provided for detecting instability in an associated feedforward audio processing system. A microphone provides a feedforward signal for processing by a feedforward filter. The processed signal may provide noise reduction and/or sound enhancement associated with the surrounding environment. The processed signal contributes to a driver signal provided to an acoustic transducer, e.g., a driver, to produce acoustic signals for a user. A processor is configured to detect an indication of instability in one or more of the signals, and to adjust a phase response of the feedforward signal path in response to detecting the indication of instability.