Frequency-Warped Audio Equalizer for Precise Band Isolation
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Solution Overview
Problem
Audio equalizers face a tradeoff between computing resource usage and accuracy, with IIR filters being resource-efficient but inaccurate, and FIR filters being accurate but resource-intensive, especially in mobile devices where adjusting one frequency band affects adjacent bands, reducing overall accuracy.
Innovation Solution
The development of frequency-warped equalization filters that transform initial filters to use computing resources more efficiently and improve accuracy by minimizing the impact of changes in one frequency band on adjacent bands, achieved through techniques like frequency warping using all-pass filters, which can be implemented in both software and hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If IIR filters are used for audio equalization, then computing resource usage is reduced, but frequency response accuracy deteriorates
Solution Approach 1:
The patent applies frequency warping transformation to modify the frequency response parameters of IIR filters. By transforming the frequency axis through warping functions, the filter characteristics are adjusted to achieve more accurate frequency response control while maintaining the computational efficiency of IIR filter structures.
Solution Approach 2:
The patent introduces frequency warping as an intermediary transformation step between the standard IIR filter design and the final frequency response. This intermediary process allows the IIR filter to achieve FIR-like accuracy by mediating the frequency response through transformation functions that correct the inherent inaccuracies of direct IIR filtering.
2Measurement precision
If FIR filters are used for audio equalization, then frequency response accuracy is improved, but computing resource usage increases
Solution Approach 1:
The patent transforms IIR filter parameters through frequency warping to achieve accuracy comparable to FIR filters. By modifying the frequency response parameters of the IIR filter through warping transformations, the system attains FIR-level precision without requiring the extensive computational resources that FIR filters demand.
Solution Approach 2:
Instead of using computationally intensive FIR filters to achieve accurate frequency response, the patent inverts the approach by using efficient IIR filters combined with frequency warping transformations. This inversion achieves the same accuracy goal through a computationally lighter pathway.
3Ease of operation
If frequency bands are adjusted in traditional equalizers, then gain control is achieved, but adjacent frequency bands are affected reducing accuracy
Solution Approach 1:
The patent applies frequency warping transformations that modify the frequency axis parameters to create more isolated frequency bands. This transformation adjusts the mapping between control slider positions and actual frequency responses, reducing the overlap and interaction between adjacent frequency bands while maintaining ease of gain control.
Data Source
AI summary
In certain embodiments, an improved audio equalization filter can be generated by frequency warping one or more digital filters having a plurality of frequency bands. Frequency warping can include, for example, transforming at least some of the frequency bands of the one or more digital filters into lower frequency bands. As a result, in various implementations the audio equalization filter may be more accurate than certain currently-available IIR equalization filters. The audio equalization filter may also be more computing-resource efficient than certain currently-available FIR equalization filters.