Recurrent Neural Network Loudspeaker Distortion Correction

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Solution Overview

Problem

Loudspeakers often exhibit nonlinearities that degrade sound quality due to factors like voice coil inductance changes, coil heating, Doppler distortion, and non-linear spring forces, which existing correction schemes fail to address effectively.

Innovation Solution

A system utilizing a recurrent neural network (RNN) with adaptive feedback to correct nonlinear distortions in loudspeakers, where the RNN receives audio input signals, outputs corrected signals, and is trained using error signals to predict and correct performance, combined with a second RNN to further refine corrections and apply non-linear distortion removal parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If existing physical model based or low-complexity black box model based correctors are used, then device complexity is reduced, but nonlinear distortion correction effectiveness deteriorates

Engineering Contradiction:
Improvecorrection system complexityVSAvoidnonlinear distortion correction effectiveness
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces traditional physical model-based correction mechanisms with a neural network-based system. The neural network learns complex nonlinear relationships between input signals and speaker distortions without requiring explicit physical models, thereby improving correction effectiveness while maintaining reasonable system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transforms the correction approach by changing from fixed physical model parameters to adaptive neural network parameters that are trained on actual speaker distortion data. This allows the system to capture complex nonlinear behaviors that physical models cannot represent, significantly improving distortion correction effectiveness.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If traditional correction schemes are used, then system simplicity is maintained, but sound quality deteriorates due to uncorrected nonlinearities

Engineering Contradiction:
Improvecorrection system structureVSAvoidsound quality
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent substitutes traditional signal processing-based correction with a neural network-based correction system. The neural network processes the input signal and generates corrected output by learning from training data, achieving superior sound quality while keeping the overall system structure relatively simple.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The neural network correction system is trained offline on speaker-specific distortion characteristics, allowing the system to adapt to each speaker's unique nonlinearities. This self-adaptation capability improves sound quality without requiring complex real-time adjustment mechanisms.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS10127921B2Adaptive correction of loudspeaker using recurrent neural network
Publication Date: 2018.11.13 HARMAN INT IND INC
  • US10127921B2 patent drawing
  • US10127921B2 patent drawing
  • US10127921B2 patent drawing

AI summary

An audio system is described that corrects for linear and nonlinear distortions. The system can include a physical loudspeaker system responsive to an audio input signal, an adaptive circuit, e.g., with a recurrent neural network, to correct for non-linear distortions from the loudspeaker.