Audio Processing Device With Parallel Filters for Stable Noise Control
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Solution Overview
Problem
Existing noise cancellation techniques in headphones fail to effectively suppress unwanted noise and can lead to unstable conditions such as 'howling' and undesired noise amplification.
Innovation Solution
The audio processing device employs multiple feedback units connected in parallel to stabilize transfer functions, preventing 'howling' and noise amplification, while achieving a broader bandwidth for effective noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If existing noise cancellation techniques are used, then noise suppression is attempted, but instability occurs causing howling and noise amplification
Solution Approach 1:
The feedback unit is divided into multiple parallel feedback units (first feedback unit, second feedback unit, etc.), each with its own filter. This segmentation allows the system to process different frequency components separately, stabilizing the transfer function across the bandwidth while maintaining noise suppression capability.
Solution Approach 2:
The system dynamically adjusts the bandwidth by controlling the cutoff frequencies of the filters in the parallel feedback units. By making the bandwidth adjustable rather than fixed, the system can optimize performance for different noise conditions while maintaining stability through appropriate filter design.
2Adaptability or versatility
If bandwidth is increased for broader noise reduction, then more frequencies are covered, but system stability deteriorates causing howling
Solution Approach 1:
The bandwidth is segmented into multiple frequency bands, each handled by a separate feedback unit with its own filter. This allows the system to achieve broader overall bandwidth while maintaining stability in each individual frequency band, preventing the howling that occurs when a single wide-band feedback loop is used.
Solution Approach 2:
Each feedback unit is designed with specific local characteristics (cutoff frequencies, filter types) optimized for its particular frequency range. This local optimization allows the overall system to have broad bandwidth while each local component maintains stability, avoiding the global instability that would result from a uniform wide-band design.
Data Source
AI summary
The disclosure provides an audio processing device comprising a first filter and a second filter. The first filter is configured to generate a first filtered signal based on an error signal, the error signal representative of audible sound at a target space. The second filter is configured to generate a second filtered signal based on the error signal. An anti-noise signal is generated based on the first filtered signal and the second filtered signal, and the anti-noise signal is included in the error signal. The first filter is connected to the second filter in parallel.