Digital Audio Filter Configuration via Pole-Zero Windowing
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Solution Overview
Problem
Modern digital audio filters become complex when attempting to compensate for room acoustics, making it difficult to control filter characteristics in a targeted manner, often resulting in undesired degradations of the sound experience due to broad effects in either the time or frequency domain.
Innovation Solution
A method for configuring digital audio filters by providing a decaying impulse response, selecting subsets of poles and zeros, determining respective subset impulse responses, windowing these responses in the time domain, and configuring the filter accordingly, allowing for highly targeted manipulation of transfer characteristics in both domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex digital audio filters are used to compensate for room acoustics, then the compensation effectiveness is improved, but the control over filter characteristics becomes difficult and sound experience degrades
Solution Approach 1:
The patent segments the impulse response into multiple portions (first portion and second portion) corresponding to different time intervals. This segmentation allows independent processing and control of early and late reflections, enabling targeted manipulation of filter characteristics while maintaining overall compensation effectiveness. The complex filter is divided into manageable segments that can be controlled separately.
Solution Approach 2:
The patent applies different processing methods to different portions of the impulse response. The first portion (early reflections) and second portion (late reflections) are handled differently through selective pole-zero manipulation. This local quality approach allows precise control over specific temporal characteristics while maintaining global compensation performance.
2Manufacturing precision
If manipulation is performed in the time domain, then time domain control is improved, but frequency domain effects become broad and undesired
Solution Approach 1:
The patent extracts specific poles and zeros from the overall transfer function and manipulates them independently. By taking out selected poles and zeros and adjusting their positions separately, the method achieves precise time domain control without causing broad frequency domain degradations. This extraction allows localized manipulation in the complex plane that translates to controlled time domain effects.
Solution Approach 2:
The patent dynamically adjusts the positions of poles and zeros in the complex plane to achieve desired impulse response characteristics. The pole-zero configuration is optimized to balance time domain precision with frequency domain stability, allowing adaptive control that prevents harmful artifacts in either domain.
3Manufacturing precision
If manipulation is performed in the frequency domain, then frequency domain control is improved, but time domain effects become broad and undesired
Solution Approach 1:
The patent extracts specific poles and zeros that correspond to particular frequency characteristics and manipulates them independently. By selecting and adjusting individual poles and zeros in the complex plane, the method achieves precise frequency domain control while maintaining controlled time domain behavior. This selective extraction prevents broad time domain artifacts that would result from overall frequency domain manipulation.
Solution Approach 2:
The patent uses dynamic pole-zero placement in the complex plane to achieve desired frequency responses. The positions of poles and zeros are optimized to produce accurate frequency domain characteristics while ensuring that the resulting impulse response maintains acceptable time domain properties. This dynamic configuration balances both domain requirements.
4Measurement precision
If highly targeted manipulation is achieved in one domain, then precision in that domain is improved, but the other domain experiences broad undesired effects
Solution Approach 1:
The patent extracts and independently manipulates specific poles and zeros to achieve highly targeted control over filter characteristics. By selecting individual poles and zeros corresponding to specific temporal or spectral features and adjusting them independently, the method achieves high precision in the desired characteristic while minimizing cross-domain degradations. This granular extraction and control prevents broad unwanted effects.
Solution Approach 2:
The patent employs dynamic optimization of pole-zero configurations to achieve precise control over specific filter characteristics. The positions of poles and zeros are adjusted to maximize precision in the target domain while maintaining stability and avoiding harmful artifacts in the other domain. This dynamic balancing act resolves the cross-domain trade-off.
Data Source
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Figure 3
Figure 4A~4B
AI summary
A method for configuring a digital audio filter (8) includes: providing a decaying impulse response in the time domain, representing at least part of the transfer characteristics of the digital audio filter (8); determining the poles and zeros of the decaying impulse response in the z-domain; selecting at least one subset of the poles and zeros of the decaying impulse response; and, for each of the at least one subset of the poles and zeros: determining a respective subset impulse response (70) in the time domain, windowing the respective subset impulse response in the time domain, and configuring the digital audio filter (8) in accordance with the windowed respective subset impulse response (72; 74; 76; 78; 80; 82; 84).