Convolution Reverb Engine With Synthesized Impulse Responses

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Solution Overview

Problem

Existing methods for generating artificial reverberation in music production are limited by their dependence on specific algorithms or impulse responses, leading to subjective evaluations and high processing costs, with algorithmic methods compromising on eigenfrequency distribution, density, and phase correlation, and convolution methods requiring extensive libraries of impulse responses.

Innovation Solution

A convolution reverberation device that combines algorithm-based parameters with a real-time convolution engine and an impulse-response synthesizer, which generates noise-like impulse responses, allowing users to control reverberation characteristics such as time, density, and damping without relying on complex algorithms or extensive impulse response files.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If algorithmic reverberation methods are used, then reverberation characteristics can be readily set by parameters, but eigenfrequency distribution, density, and phase correlation are compromised

Engineering Contradiction:

Improveparameter controlVSAvoidreverberation quality

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent merges the parameter-based control advantage of algorithmic methods with the quality advantage of convolution methods by using a hybrid architecture. The system combines a feedback delay network (algorithmic) with impulse response filtering (convolution), allowing users to control reverberation through parameters while maintaining high eigenfrequency distribution, density, and phase correlation through the impulse response component.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The reverberation system uses composite signal processing techniques, combining algorithmic delay-line methods with convolution-based impulse response methods. This composite approach creates a hybrid reverberation engine that achieves both parameter controllability and high audio quality, resolving the contradiction between ease of operation and manufacturing precision.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If convolution method is used with extensive impulse response libraries, then reverberation quality is improved, but device complexity and costs increase

Engineering Contradiction:

Improvereverberation qualityVSAvoidimpulse response library requirements

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system generates its own impulse responses algorithmically through a feedback delay network, eliminating the need for external impulse response libraries. The feedback delay network synthesizes impulse responses on-demand based on user-defined parameters, making the system self-sufficient and removing the complexity of managing extensive impulse response collections.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical approach of storing pre-recorded impulse responses in libraries with an algorithmic synthesis approach using feedback delay networks. This substitution eliminates the need for physical or digital impulse response files, reducing device complexity while maintaining the ability to generate high-quality reverberation through mathematical modeling.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Duration of action of moving object

If convolution method is used with short impulse responses, then short reverberation is achieved, but reverberation density is low

Engineering Contradiction:

Improvereverberation timeVSAvoidreverberation density

Core Design Contradiction:

Duration of action of moving objectVSManufacturing precision

Solution Approach 1:

The feedback delay network dynamically adjusts the density and distribution of reflections based on user-defined parameters, allowing the system to maintain high reverberation density regardless of the selected reverberation time. The algorithmic nature of the feedback delay network enables it to generate appropriate reflection patterns for both short and long reverberation times, overcoming the limitation of fixed impulse response densities.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7860256B1Artificial-reverberation generating device

Publication Date: 2010.12.28 APPLE INC

AI summary

An artificial-reverberation generating device comprises in one embodiment a convolution engine in association with an impulse-response synthesizer. The impulse-response synthesizer preferably comprises a noise synthesizer and a control means for controlling one or more parameters of the noise synthesizer, the parameters corresponding to adjustable characteristics of the generated reverberation. The noise synthesizer is preferably a pseudo-random number generator, which is multiplied by the output signal of a density generator. The density generator output signal advantageously takes the form of a series of spikes of variable duration and time-interval spacing. The multiplier outputs feed a phase-correlation stage, followed by a time-variant filter stage and a time-variant amplifier stage. The output of the time-variant amplifier stage forms the output of the impulse-response synthesizer and is used to feed impulse-response information to the convolution engine.