Audio Signal Processing for Smooth Initial Reflections and Reverberation

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Solution Overview

Problem

Existing technologies struggle to improve the sound quality of initial reflected sound in acoustic systems, particularly in simulating and enhancing the initial reflected sound and reverberant sound in virtual spaces.

Innovation Solution

An audio signal processing method and apparatus that divides the reproduction space into areas, groups sound sources, generates initial reflected sound and reverberant sound control signals based on virtual sound sources, and adjusts gain and delay to simulate accurate and natural sound reflections and reverberations using an audio signal processing apparatus with components like an area setter, grouping portion, initial reflected sound control signal generator, mixer, reverberant sound control signal generator, adder, and output adjuster.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional reflected sound generators using FIR filters are used, then reflected sound can be generated, but sound quality of initial reflected sound cannot be improved

Engineering Contradiction:
Improvesound qualityVSAvoidprocessing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the reflected sound into two distinct components: initial reflected sound and rear reverberant sound. Each component is processed separately through different pathways (first and second FIR filters) to apply different processing characteristics, thereby improving sound quality while maintaining manageable system complexity through functional segmentation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different processing characteristics to different parts of the reflected sound signal. The initial reflected sound component receives different filter processing compared to the rear reverberant sound component, allowing each part to be optimized for its specific acoustic characteristics and improving overall sound quality.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If simple reflected sound generation is used, then device complexity is low, but sound quality and spatial expansion are insufficient

Engineering Contradiction:
Improvesound qualityVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces spatial dimensionality by dividing the reproduction space into multiple areas and assigning different reflected sound characteristics to different spatial zones. This creates rich spatial expansion and natural sound field distribution, transforming a one-dimensional simple reflection model into a multi-dimensional spatial audio system.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent implements dynamic processing by adjusting gain and delay parameters based on the positional relationship between sound sources and reproduction points. The processing characteristics are not fixed but adapt dynamically to the spatial configuration, creating more natural and flexible sound reflection behavior.

Inventive Principle:
Principle #15Dynamics

3Ease of operation

If direct reflection modeling is used, then initial reflected sound can be generated, but transitions to reverberant sound are abrupt and unnatural

Engineering Contradiction:
ImprovenaturalnessVSAvoidsound quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by processing the reflected sound signal in advance through multiple stages: first generating the initial reflected sound component, then transitioning to the rear reverberant sound component with adjusted processing characteristics. This staged approach ensures smooth transitions and natural evolution of the reflected sound over time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuity of useful action by ensuring seamless transition between initial reflected sound and rear reverberant sound components. The processing parameters are continuously adjusted to maintain natural flow, avoiding abrupt changes and ensuring the reflected sound evolves smoothly from direct reflection to diffuse reverberation.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4060655B1Audio signal processing method, audio signal processing apparatus and audio signal processing program
Publication Date: 2025.08.27 YAMAHA CORP
  • EP4060655B1 patent drawingFigure 1
  • EP4060655B1 patent drawingFigure 2
  • EP4060655B1 patent drawingFigure 3

AI summary

An audio signal processing method includes obtaining an audio signal of a sound source, performing first filter processing on the audio signal to generate an imaginary sound source of a virtual space, performing second filter processing on the audio signal to adjust a tone of the imaginary sound source, and outputting an initial reflected sound control signal generated by using the audio signal on which the first filter processing and the second filter processing have been performed, in a first case where the first filter processing is performed before the second filter processing, the first filter processing is performed on the audio signal, and the second filter processing is performed on the audio signal on which the first filter processing has been performed, and in a second case where the second filter processing is performed before the first filter processing, the second filter processing is performed on the audio signal, and the first filter processing is performed on the audio signal on which the second filter processing has been performed.