Adaptive Feedback Noise Reduction for ANC Audio Playback
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Solution Overview
Problem
Existing audio playback devices face issues with feedback noise reduction, leading to distortion and noise when digital gain is too large, particularly in active noise cancellation modes, and high sound pressure levels can cause overload distortion noise.
Innovation Solution
Adjust feedback noise-reduction parameters based on characteristic analysis of ambient and audio signals in active noise cancellation mode, using low-frequency-band signal values to dynamically optimize noise reduction, disabling feedback when unnecessary, and employing feedforward noise reduction for small ambient signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If feedback noise reduction is applied in active noise cancellation mode, then noise cancellation effect is improved, but audio quality deteriorates due to distortion and noise from large digital gain
Solution Approach 1:
The patent dynamically adjusts the feedback noise reduction parameter based on real-time analysis of ambient sound characteristics and audio signal characteristics. The system transitions from static parameter settings to dynamic adaptation, modifying the degree of feedback noise reduction according to current acoustic conditions to prevent distortion while maintaining noise cancellation effectiveness.
Solution Approach 2:
The patent changes the feedback noise reduction parameter based on characteristic values of ambient sound and audio signal in different frequency bands. By monitoring parameters such as low-frequency-band signal characteristics and adjusting the feedback noise reduction parameter accordingly, the system optimizes the balance between noise cancellation and audio quality without causing overload distortion.
2Manufacturing precision
If digital gain is increased to compensate for audio loss, then audio quality is improved, but distortion and noise increase
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the characteristics of the audio signal and ambient sound, then adjusts the feedback noise reduction parameter based on this information. This closed-loop control prevents excessive digital gain application by adapting the noise reduction strength to current conditions, thereby avoiding distortion while maintaining audio quality.
Solution Approach 2:
The patent applies feedback noise reduction selectively rather than uniformly across all conditions. By analyzing characteristic values and applying noise reduction only when and where it is beneficial, the system avoids the excessive action that would cause distortion, achieving partial action optimized for each specific acoustic scenario.
3Object-affected harmful factors
If feedback noise reduction parameter is increased to reduce feedback noise, then noise cancellation effect is improved, but audio signal quality deteriorates due to overload distortion
Solution Approach 1:
The patent transitions from a fixed feedback noise reduction parameter to a dynamic adjustment mechanism. The system continuously evaluates ambient sound characteristics and audio signal characteristics, adapting the feedback noise reduction parameter in real-time to maintain audio signal quality while effectively reducing feedback noise under varying conditions.
Solution Approach 2:
The patent changes the feedback noise reduction parameter based on characteristic values from frequency band analysis of ambient sound and audio signal. By monitoring parameters such as low-frequency-band signal characteristics and adjusting accordingly, the system prevents parameter values that would cause overload distortion while maintaining effective noise cancellation.
Data Source
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AI summary
An audio data processing method, applied to an audio playback device, comprising: acquiring a current audio playback mode corresponding to the audio playback device (202); if the current audio playback mode is an active noise reduction mode, collecting ambient sound, and performing characteristic analysis on a preset frequency band signal of the ambient sound to obtain a first low-frequency band signal characteristic value corresponding to the ambient sound (204); performing characteristic analysis on the preset frequency band signal of an audio signal played back by the audio playback device to obtain a second low-frequency band signal characteristic value corresponding to the audio signal (206); and if the characteristic value of the first low-frequency band signal is greater than a first preset threshold, adjusting a feedback noise reduction parameter of the audio playback device on the basis of the characteristic value of the second low-frequency band signal (208).