Sound Signal Processing for Localization and Space Expansion

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Solution Overview

Problem

Existing sound signal processing methods fail to achieve clear sound image localization and richer space expansion, as they primarily rely on adding reverberant sound without effectively controlling acoustic characteristics in enclosed spaces, which limits the ability to physically alter the reverberant characteristics of a hall.

Innovation Solution

A sound signal processing method and device that utilize a combination of directional and omnidirectional microphones, high and low directivity speakers, and FIR filters to generate and control direct, early reflection, and reverberant sound signals, allowing for precise sound localization and space expansion by adjusting gain, mixing, and convolving sound signals with measured impulse responses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If reverberant sound is added to enhance space perception, then space expansion is improved, but sound image localization becomes blurred

Engineering Contradiction:
Improvespace expansionVSAvoidsound image localization
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the indirect sound into two distinct components: early reflection sound and reverberant sound. By processing these components separately through different signal paths with independent gain controls, the system can selectively enhance space perception through reverberant sound while preserving clear sound image localization through controlled early reflection sound, thereby resolving the contradiction between space expansion and localization clarity.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If physical changes are made to alter reverberant characteristics of a hall, then acoustic characteristics are improved, but facility complexity and cost increase significantly

Engineering Contradiction:
Improveacoustic characteristicsVSAvoidfacility scale
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces physical mechanical modifications to the hall structure with an electronic signal processing system. By using microphones to capture sound, FIR filters to generate impulse responses, and speakers to reproduce processed sound, the system achieves adjustable acoustic characteristics without any physical changes to the hall, thereby resolving the contradiction between acoustic adaptability and facility complexity.

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

3Measurement precision

If sound signals are processed to achieve clear localization, then sound image localization is improved, but space expansion becomes limited

Engineering Contradiction:
Improvesound image localizationVSAvoidspace expansion
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent merges the direct sound signal with both early reflection sound and reverberant sound in a combined output path. This integration allows the system to simultaneously provide clear sound image localization through the direct and early reflection components while achieving rich space expansion through the added reverberant sound, thereby resolving the contradiction between localization precision and space expansion.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves clearer sound image localization and richer space expansion by controlling sound signals based on the position of the sound source, distributing sound signals to multiple speakers, and adjusting levels and delays, resulting in a more immersive audio experience without relying on physical changes to the acoustic space.

Implementation Method 1

an impulse response convolver configured to convolve an input audio signal with the modified impulse response

Methodology Applied
Scientific EffectConvolution:

Implementation Method 2

a sound signal processing method for processing an obtained sound signal

Methodology Applied
Scientific EffectAcoustic to electrical transduction:

Data Source

PatentEP3920177B1Sound signal processing method, sound signal processing device, and sound signal processing program
Publication Date: 2024.02.21 YAMAHA CORP
  • EP3920177B1 patent drawingFigure 1
  • EP3920177B1 patent drawingFigure 2
  • EP3920177B1 patent drawingFigure 3

AI summary

A sound signal processing method includes receiving a sound signal, generating an early reflection sound control signal that reproduces an early reflection sound and a reverberant sound control signal that reproduces a reverberant sound from the sound signal, controlling a volume of the sound signal and distributing the sound signal to generate a direct sound control signal that reproduces a direct sound, and mixing the direct sound control signal, the early reflection sound control signal, and the reverberant sound control signal to generate an output signal.