IIR Graphic Equalizer Tuning for Accurate Spectral Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Graphic equalizers using infinite impulse response (IIR) filter sections often exhibit inaccuracies due to filter band interactions, resulting in responses that differ significantly from operator expectations, leading to filter inaccuracy and asymmetry.
Innovation Solution
An audio spectral correction system and method that employs closed-form algorithms to tune IIR filter sections, providing accurate and intuitive frequency responses with low complexity and minimal processing overhead, by adjusting gain settings and quality factors to achieve proportional and symmetric filter behavior, thereby correcting the composite response to match operator specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If IIR filter sections are cascaded together to reduce computing resources, then computational efficiency is improved, but filter accuracy deteriorates due to band interactions
Solution Approach 1:
The patent applies parameter changes by computing corrected gain settings for each IIR filter section based on the interaction between adjacent bands. Instead of using direct operator settings, the system calculates adjusted parameters (gain, quality factor) that compensate for the interaction effects, thereby maintaining accuracy while using efficient IIR filtering.
Solution Approach 2:
The patent implements a feedback mechanism where the gain settings of filter sections are iteratively adjusted based on the measured or calculated interaction between adjacent bands. The corrected gain settings are derived by considering the influence of neighboring filters, creating a feedback loop that eliminates accuracy degradation from band interactions.
2Device complexity
If peaking filter sections are used for each equalizer band, then device complexity is reduced, but response accuracy deteriorates due to filter interaction
Solution Approach 1:
The patent changes the parameters of the peaking filter sections by computing corrected gain and quality factor values that account for interactions between adjacent filter bands. This allows the simple peaking filter structure to produce accurate overall frequency responses by adjusting individual section parameters rather than changing the fundamental filter topology.
3Manufacturing precision
If iterative error minimization methods are used to improve equalizer accuracy, then filter accuracy is improved, but computational overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-computing correction factors or lookup tables that capture the interaction effects between filter bands. During operation, instead of performing iterative error minimization, the system applies these pre-calculated corrections directly to the gain settings, achieving high accuracy with minimal real-time computational overhead.
Data Source
AI summary
Systems and methods to provide an audio spectral correction can be implemented in a variety of applications. Such systems and methods can include an equalizer design that uses efficient filter sections tuned with a closed form algorithm to give an accurate and intuitive frequency response with low complexity and minimal processing overhead. Embodiments can enable efficient and accurate control of reverberation time vs. frequency in artificial reverberators. Embodiments can enable efficient realization of a cascade combination of multi-band equalization functions as a single multi-band equalizer function, in which such functions can be expressed as graphic equalization functions using the same set of center frequencies as the cascade combination of multi-band equalization functions. Additional apparatus, systems, and methods are disclosed.