Upright Piano Acoustic Resonator Standing Wave Suppression
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Solution Overview
Problem
Upright pianos face challenges in suppressing standing waves generated in their acoustic space, which can alter the frequency characteristic and affect sound quality, and existing solutions like acoustic resonators can impair the external appearance and cause unintended effects on the frequency characteristic.
Innovation Solution
The implementation of pilaster-shaped acoustic resonators with openings positioned at the left or right ends of the upper or lower front boards, which act as resonance tubes, effectively suppress standing waves by dissipating energy through sound-absorbing materials like urethane foam, minimizing impact on the frequency characteristic and maintaining the piano's appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an acoustic resonator is arranged in the case of an upright piano to suppress standing waves, then the standing waves of specific resonance frequency are suppressed, but the frequency characteristic is disturbed and the sound field inside the case is affected
Solution Approach 1:
The patent applies local quality by positioning the acoustic resonator specifically at the left or right end side of either the lower end side of the upper front board or the upper end side of the lower front board. This localized placement targets specific standing wave patterns in the case while minimizing disruption to the overall sound field and frequency characteristic of the piano.
Solution Approach 2:
The patent utilizes the spatial dimension by strategically positioning the resonator opening at specific locations on the front board rather than placing it centrally or randomly. This dimensional positioning allows the resonator to suppress standing waves effectively while maintaining the integrity of the sound field in other regions of the case.
2Object-affected harmful factors
If the opening of the acoustic resonator is positioned at the antinode of sound pressure in a fixed vibration mode to reduce sound pressure of a specific frequency, then the standing wave is suppressed, but the sound pressure of unintended frequencies is also reduced causing unintended effects
Solution Approach 1:
By positioning the resonator opening at the left or right end side of the front board, the patent creates a localized effect that targets specific standing wave modes without broadly affecting the entire frequency spectrum. This selective positioning ensures that only problematic frequencies are suppressed while maintaining the piano's overall frequency response characteristics.
3Object-affected harmful factors
If an acoustic resonator is arranged in the case to suppress standing waves, then the sound quality is improved, but the external appearance of the piano is impaired
Solution Approach 1:
The patent merges the acoustic resonator with the existing front board structure of the piano. By integrating the resonator into the left or right end side of the upper or lower front board, the design combines the sound suppression function with the piano's aesthetic structure, minimizing visual impact while maintaining acoustic effectiveness.
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
This configuration successfully reduces standing waves at specific resonance frequencies, minimizing sound muffling and maintaining the piano's frequency characteristic and external appearance, as demonstrated by measurement results showing decreased sound pressure levels at targeted frequencies.
Implementation Method 1
resonance tube provided with a hollow region and an opening, disposed in the internal space, in which the opening is disposed at a left or right end side of either a lower end side of the upper front board or an upper end side of the lower front board
Implementation Method 2
resonance tube provided with a hollow region and an opening
Data Source
AI summary
An upright piano includes an internal space enclosed by a case including an upper front board disposed above a key bed and a lower front board disposed below the key bed, and a resonance tube in which a hollow region having an opening is formed and that is disposed in the internal space, in which the opening is disposed at the left end of the lower end of the upper front board or the upper end of the lower front board, or at the right end of the lower end of the upper front board or the upper end of the lower front board.