A case study on room acoustic solutions for social gathering places
Résumé
Small social gathering places, such as restaurants and cafeterias, suffer from the problem of noise, which can come from the outside (traffic) or from the inside (many people speaking at once). In order to mitigate the noise problem, this project proposes a comprehensive engineering approach involving the design, development and implementation of room acoustic solutions for sound absorption in the aforementioned social gathering places, at frequencies below 1000 Hz. A real restaurant is chosen in this study. Based on the concept of acoustic metasurfaces and coiled spaces, we design a unit cell (UC) which provides high absorption and tunability while maintaining a thickness of approximately &ₗambda;/20, thus being more practical than using the quarter wavelength rule. The target frequencies and locations at which the UC acts are calculated via both frequency and time domain numerical methods, namely the fast multipole boundary element method (FMBEM) and the finite-difference time-domain (FDTD) method. FMBEM is applied to accurately predict the room modes and sound pressure level at different frequencies. While FDTD simulations give the sound pressure level with elapsed time, which is convenient to extract room acoustic parameters such as reverberation time. The two numerical techniques are compared and validated by measurement data. In addition, several latest 3D printing techniques are evaluated to ensure that the new meta-material design can be realized in practice. Laser sintering (LS) and PolyJet (PJ) techniques are eventually selected due to their high flexibility and accuracy. Printed parts are validated numerically and experimentally for sound absorption, having a fair match between results. Overall, the project aims at establishing a comprehensive process involving design, simulations and manufacturing to improve the acoustic performance of social gathering places.
Origine : Fichiers produits par l'(les) auteur(s)
Licence : CC BY - Paternité
Licence : CC BY - Paternité