Tilt-Type Filter Coefficient Control for Wideband EQ Correction
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Solution Overview
Problem
Existing parametric equalizers (PEQs) with flat type filter elements struggle to easily adjust frequency characteristics, particularly when the frequency characteristics of the playback system are inclined, requiring multiple elements and complex parameter settings to achieve flat characteristics over a wide frequency range.
Innovation Solution
An audio processing apparatus with a processor that generates filter coefficients based on parameters defining a frequency response with lower and upper inclined portions and a center inclined portion, allowing for precise control of frequency characteristics within specific frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing flat type filter elements are used in PEQ, then the frequency characteristics can be adjusted in narrow frequency bands, but multiple filter elements and complex parameter settings are required to correct gradients over wide frequency bands
Solution Approach 1:
The patent combines multiple filter functions into a single Tilt-Type Filter (TTF) element that can simultaneously provide lower inclined portion, upper inclined portion, and center flat portion characteristics. This merging of previously separate flat type filter elements into one unified TTF structure allows wide frequency band correction while reducing the total number of required filter elements.
Solution Approach 2:
The TTF element is designed with multi-functionality to handle diverse frequency correction needs. It can operate as a low-pass filter, high-pass filter, or band-pass filter depending on parameter settings, and can correct both narrow and wide frequency band gradients using the same filter structure with different parameter configurations.
2Ease of operation
If existing flat type filter elements are used, then simple parameter settings work for narrow bands, but complex individual parameter setting is required for each filter element
Solution Approach 1:
By merging multiple filter element parameter settings into a unified TTF parameter structure, the patent reduces the total number of parameters that need to be individually configured. The TTF uses a standardized parameter set that defines the lower inclined portion, upper inclined portion, and center flat portion characteristics collectively, rather than requiring separate parameters for each flat type element.
3Manufacturing precision
If flat type filter elements with cosine curve shapes are used, then frequency response control is achieved in limited sections, but gentle gradients over wide frequency bands cannot be corrected
Solution Approach 1:
The TTF divides the frequency response into three distinct sections: lower inclined portion, center flat portion, and upper inclined portion. Each section can be independently configured with specific gradient values and frequency ranges, allowing precise control over wide frequency bands while maintaining the ability to address specific frequency regions individually.
Solution Approach 2:
The TTF parameters are designed to be dynamically adjustable to adapt to different frequency correction needs. The filter can be configured to emphasize different portions (lower inclined, upper inclined, or center flat) depending on the specific acoustic space characteristics and correction requirements, providing versatile adaptation to various scenarios.
Data Source
AI summary
A system for implementing filter control includes an audio processing apparatus, an analog-to-digital converter, a digital-to-analog converter, a filter, and a processor. The processor is configured to receive parameters that define a frequency response in a given frequency bandwidth. The processor is also configured to generate, based on the parameters, a response curve representative of a frequency response of a filter. The processor is also configured to generate, based on the response curve, a filter coefficient of the filter. The lower inclined portion corresponds to, within the given frequency bandwidth, a frequency bandwidth that is lower than a frequency bandwidth corresponding to the upper inclined portion.