Convolution-Based Piano Sound Generation with Impulse Response Filtering

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Solution Overview

Problem

Conventional electronic pianos struggle to accurately simulate the resonant tones of acoustic pianos using feedback filter signal processing techniques, resulting in unrealistic sound reproduction.

Innovation Solution

A musical note generation device and method that involves convolving sound waveform data with impulse response data and applying filtering to reduce the amplitudes of frequency components of fundamental tones and harmonics, mimicking the effect of an acoustic piano's damper pedal, to produce natural resonant tones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If feedback filter signal processing techniques are used to simulate resonant tones, then the device complexity is reduced, but the sound realism deteriorates

Engineering Contradiction:
Improvesignal processing complexityVSAvoidsound realism
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent records actual resonant tones from an acoustic piano with damper pedal depressed and stores them as impulse response data. This copied real-world data is then used for convolution processing, achieving realistic sound without complex real-time signal processing algorithms.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces complex mechanical signal processing (feedback filters, reverbs, resonators) with a simpler convolution-based system that uses pre-recorded impulse response data, substituting mechanical complexity with data-driven processing.

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

2Manufacturing precision

If convolution with impulse response is applied, then the sound realism is improved, but the processing complexity increases

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

Solution Approach 1:

The impulse response data is recorded and prepared in advance before actual use. This preliminary action transfers the complex processing requirements to the data preparation phase, allowing simpler real-time convolution operations during sound generation.

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If amplitudes of fundamental tone and harmonics are reduced, then the natural resonant tone quality is improved, but the energy of the sound wave is reduced

Engineering Contradiction:
Improveresonant tone qualityVSAvoidsound energy
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent selectively reduces amplitudes only for specific frequency components (fundamental tone and harmonics corresponding to pressed keys) while preserving other frequency components. This local quality adjustment maintains overall sound energy while improving resonant tone realism.

Inventive Principle:
Principle #3Local quality

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 solution effectively generates piano sound waveform data that closely replicates the natural resonant tones of an acoustic piano, providing a more realistic and authentic sound experience.

Implementation Method 1

a convolution operation process of generating convolved sound waveform data by convolving first sound waveform data corresponding to the pitch information associated with a specified key with second sound waveform data corresponding to an impulse response

Methodology Applied
Scientific EffectConvolution:

Implementation Method 2

a third sound waveform data generation process of generating third sound waveform data by respectively reducing, among frequency components included in the convolved sound waveform data generated by the convolution operation process, amplitudes of respective frequency components of a fundamental tone and harmonics of the fundamental tone

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP3340234B1Musical note generation device, electronic musical instrument, method, and storage medium
Publication Date: 2020.05.13 CASIO COMPUTER CO LTD
  • EP3340234B1 patent drawingFigure 1
  • EP3340234B1 patent drawingFigure 2
  • EP3340234B1 patent drawingFigure 3

AI summary

A musical note generation device includes at least one processor, performing a process of generating convolved sound waveform data by convolving first sound waveform data corresponding to pitch information associated with a specified key with second sound waveform data corresponding to an impulse response; a process of generating third sound waveform data by respectively reducing, among frequency components included in the generated convolved sound waveform data, amplitudes of respective frequency components of a fundamental tone and harmonics of the fundamental tone corresponding to a pitch indicated by the pitch information; and a process of outputting piano sound waveform data generated on the basis of the generated third sound waveform data generated.