Acoustic Responses of Eight Cymatic Patterns as Recital Hall Diffusers

• Main Authors: Anastasia Mimosa, 毛娟璇
• Other Authors: Shin-Jyun Tsaih
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/qyr8hr

碩士 === 國立臺灣科技大學 === 建築系 === 107 === Optimal room acoustics is one of the major design goals to achieve in a recital hall. Proper uses of acoustic materials create good acoustics. Chladni’s cymatic pattern was used in this study as a new perspective to provide the proper diffusive sound field in a recital hall. A unique thing about this cymatic pattern is that the pattern is a solid visualization transmission from a specific frequency. In other words, humans can see this specific sound shaping. With different frequencies, unique cymatic patterns are observed. Based on the known octave band frequencies, the eight frequencies of 62 Hz, 123 Hz, 247 Hz, 494 Hz, 988 Hz, 1976 Hz, 3951 Hz, and 7902 Hz were selected to create cymatic patterns and used as the surface of the diffuser in this study. These cymatic diffusers were proposed to be placed inside the recital hall to study the acoustic responses. The placements, materials, and pattern’s thickness of the eight cymatic diffusers were also discussed and evaluated. Therefore, the objective of this research was to study the acoustic responses of the selected eight cymatic diffusers for room acoustics parameters such as early decay time (EDT), reverberation time (T30) and clarity (C80). The acoustic responses were then compared with the recommended acoustic design guidelines for recital halls from ISO 3382 and Norwegian Standard NS-8178. For all eight frequency patterns with wood and on a 1-side wall with a thickness of 400 mm, the simulated EDT, T30 and C80 values are within recommended recital hall design goals. Thus, these cymatic patterns can be used as an improvement for recital hall. Because the EDT, T30 and C80 results are all within the recommended design range, listening evaluations with 35 participants on eight cymatic patterns were performed. Although 76% of the participants thought that it is not easy to distinguish the difference between reverberant, music clarity and loudness listening impression for the eight cymatic patterns; the 1976 Hz sample stood out as the most preferable music performance space. Additional analysis for musician group was conducted. Musicians preferred to have 3951 Hz and 497 Hz samples as the best music performance spaces. In short, this research documents the acoustic responses of the cymatic diffusers in a recital hall 3D model, and the promising results suggest that the cymatic pattern is a potential solution to enhance room acoustic quality.