Resonance Tone Generating Apparatus for Piano Simulation
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Solution Overview
Problem
Existing resonance tone generating apparatuses for electronic musical instruments fail to accurately reproduce piano resonance tones due to limitations in changing resonance tones with the damper pedal operation and require large-scale circuits that do not consider the piano structure, resulting in insufficient resonance tone reproduction.
Innovation Solution
A resonance tone generating apparatus that includes an impulse response data storing unit, a product-sum operation unit with delay, multiplying, and adder units, and a feedback unit to perform a convolution operation on musical signal data, allowing for dynamic adjustment of resonance tone levels and feedback to simulate the prolonged resonance of piano strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cross-fade technique is used to change mixing ratio of musical tone to resonance tone, then the resonance tone level can be adjusted, but the resonance tone itself does not change and the change due to damper pedal pressing operation is poor
Solution Approach 1:
The patent applies dynamics by making the resonance tone characteristics changeable through damper pedal operation. The resonance tone generating apparatus dynamically adjusts both the mixing ratio and the resonance tone characteristics themselves based on pedal pressing depth, transforming a static resonance tone into a dynamic one that adapts to playing conditions.
Solution Approach 2:
The patent changes multiple parameters simultaneously: both the mixing ratio of musical tone to resonance tone and the resonance tone characteristics themselves are adjusted based on damper pedal pressing depth. This multi-parameter adjustment enables more accurate reproduction of piano resonance tones while maintaining adaptability.
2Adaptability or versatility
If plural string resonance circuits are provided for each keyboard zone, then resonance tone generation capability is improved, but the circuit scale becomes large and sufficient resonance tone cannot be reproduced considering piano structure
Solution Approach 1:
The patent applies universality by creating a single resonance tone generating apparatus that serves multiple functions: it generates resonance tones for different keyboard zones, handles both damper pedal and sustain pedal operations, and reproduces various piano resonance characteristics. This eliminates the need for separate circuits for each keyboard zone while maintaining comprehensive resonance tone generation capability.
Solution Approach 2:
The patent uses copying by storing impulse response data that replicates the complex resonance characteristics of piano strings. Instead of building complex physical resonance circuits for each zone, the system copies the essential resonance behavior through stored impulse response data, achieving accurate reproduction with simpler circuit architecture.
3Reliability
If FIR filter is used to perform convolution operation, then resonance tone data can be generated from musical signal data, but the circuit complexity increases and processing time is consumed
Solution Approach 1:
The patent applies preliminary action by pre-storing impulse response data in a memory unit before actual resonance tone generation is needed. This pre-prepared data can be quickly retrieved and processed through simpler convolution operations, reducing the complexity of real-time processing while maintaining accurate resonance tone reproduction.
Data Source
AI summary
A product-sum operation circuit has delay circuits of the first to the (n−1)th stage for delaying musical tone data, multiplying circuits 60-6(n−1) for multiplying the musical signal data or the delayed musical signal data output from the delay circuits by impulse response coefficients, and adders 71-7(n−1) for summing up data output from the multiplying circuits. The product-sum operation circuit is provided with a feed back circuit. The feed back circuit includes a multiplying circuit 80 that receives the delayed data from the delay circuit at the (n−1)th stage and multiplies the received data by a multiplication coefficient, and an adder 81 for adding data from the multiplying circuit 80 to the delayed data from the delay circuit at the “p”th stage.