Adaptive Digital Feedback Reduction for Full-Range Audio Detection

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Solution Overview

Problem

Conventional digital feedback reduction (DFR) algorithms are inadequate in detecting feedback frequencies below 200 Hertz and above ¼ of the sample rate, fail to provide reliable detection of bass frequencies, and lack automated mechanisms to remove notch filters, leading to reintroduction of feedback and audio distortion.

Innovation Solution

Implementing adaptive DFR techniques that utilize adaptive lattice filters and isolation filters to track feedback frequencies, apply notch filters and system gain reduction, and include an automated release option to mitigate feedback dynamically, supporting a wider frequency range from 20 Hertz to 20 KHz, and ensuring reliable detection without audio distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional DFR algorithms use frequency tracking with digital notch filters, then feedback tones can be filtered out, but the algorithms fail to detect feedback frequencies below 200 Hz and above 1/4 of the sample rate

Engineering Contradiction:

Improvefeedback frequency detection accuracyVSAvoidfrequency range coverage

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic frequency tracking system that continuously monitors and adapts to feedback frequencies across the entire audio spectrum. The system uses adaptive filtering techniques that automatically adjust their parameters based on the detected feedback characteristics, enabling reliable detection from 20 Hz to 20 kHz rather than being limited to a fixed frequency range.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the detection parameters and algorithm configuration based on the frequency range being analyzed. By dynamically adjusting detection thresholds, filter bandwidths, and analysis window sizes according to the specific frequency band, the system achieves accurate feedback detection across the full audible spectrum including bass frequencies below 200 Hz and high frequencies up to 20 kHz.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If conventional DFR algorithms apply notch filters to remove feedback tones, then feedback can be reduced, but there is no automated mechanism to remove the notch filters causing reintroduction of feedback

Engineering Contradiction:

Improvefeedback reduction effectivenessVSAvoidautomated filter management

Core Design Contradiction:

Object-generated harmful factorsVSExtent of automation

Solution Approach 1:

The patent implements a closed-loop feedback system that continuously monitors the audio signal for the presence of feedback tones. When feedback is detected, notch filters are automatically applied; when feedback ceases to be present, the system automatically removes the filters. This automated feedback mechanism prevents both the persistence of unnecessary filters and the reintroduction of mitigated feedback.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The DFR system performs self-management by automatically detecting when feedback tones are present or absent and相应地 applying or removing notch filters without human intervention. The system monitors its own performance and autonomously adjusts its filtering state, ensuring continuous feedback suppression while avoiding the reintroduction of previously mitigated tones.

Inventive Principle:

Principle #25Self-service

3Device complexity

If conventional DFR algorithms use quantized feedback frequency tracking, then implementation is simpler, but detection reliability is poor especially for bass frequencies

Engineering Contradiction:

Improvetracking algorithm complexityVSAvoidfeedback detection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces the conventional quantized, discrete frequency tracking approach with a continuous, adaptive spectral analysis method. Instead of checking predefined frequency bins, the system uses continuous spectral estimation techniques that provide smooth, high-resolution frequency tracking across the entire spectrum, significantly improving detection reliability for bass frequencies and other challenging bands.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Use of energy by moving object

If conventional DFR algorithms are configured for limited frequency ranges, then computational load is reduced, but they cannot detect feedback above 1/4 of the sample rate

Engineering Contradiction:

Improvecomputational efficiencyVSAvoiddetectable frequency range

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent divides the frequency spectrum into multiple analysis bands, each processed with optimized algorithms tailored to that band's characteristics. This segmentation allows the system to maintain computational efficiency for each individual band while collectively covering the entire frequency range from 20 Hz to 20 kHz, including frequencies above 1/4 of the sample rate that conventional single-band approaches cannot detect.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250378815A1Adaptive digital feedback reduction

Publication Date: 2025.12.11 SHURE ACQUISITION HLDG INC

AI summary

Methods and apparatuses are described to provide digital feedback reduction (DFR) that may reduce or eliminate the presence of feedback in digital audio signals. The DFR techniques as described herein may implement a fast and reliable detection process to help ensure a minimal false detection probability. Furthermore, the DFR techniques as described herein may support a wider frequency range compared to conventional DFR techniques, for instance from 20 Hz up to at least 20 kHz.