A Trial Acoustic Improvement in a Lecture Hall with MPP Sound Absorbers and FDTD Acoustic Simulations
Open Access
- 10 March 2021
- journal article
- research article
- Published by MDPI AG in Applied Sciences
- Vol. 11 (6), 2445
- https://doi.org/10.3390/app11062445
Abstract
Sound absorbing micro-perforated panels (MPPs) are being increasingly used because of their high quality in terms of hygiene, sustainability and durability. The present work investigates the feasibility and the performance of MPPs when used as an acoustic treatment in lecture rooms. With this purpose, three different micro-perforated steel specimens were first designed following existing predictive models and then physically manufactured through 3D additive metal printing. The specimens’ acoustic behavior was analyzed with experimental measurements in single-layer and double-layer configurations. Then, the investigation was focused on the application of double-layer MPPs to the ceiling of an existing university lecture hall to enhance speech intelligibility. Numerical simulations were carried out using a full-spectrum wave-based method: a finite-difference time-domain (FDTD) code was chosen to better handle time-dependent signals as the verbal communication. The present work proposes a workflow to explore the suitability of a specific material to speech requirements. The measured specific impedance complex values allowed to derive the input data referred to MPPs in FDTD simulations. The outcomes of the process show the influence of the acoustic treatment in terms of reverberation time () and sound clarity (). A systematic comparison with a standard geometrical acoustic (GA) technique is reported as well.
Funding Information
- Ministero dell’Istruzione, dell’Università e della Ricerca (PRIN 2017, grant number 2017T8SBH9)
This publication has 47 references indexed in Scilit:
- Optimizing stepwise rotation of dodecahedron sound source to improve the accuracy of room acoustic measuresThe Journal of the Acoustical Society of America, 2013
- Converting Sabine absorption coefficients to random incidence absorption coefficientsThe Journal of the Acoustical Society of America, 2013
- Computer simulations in room acoustics: Concepts and uncertaintiesThe Journal of the Acoustical Society of America, 2013
- A numerical study of double-leaf microperforated panel absorbersApplied Acoustics, 2006
- A note on the effect of vibration of a microperforated panel on its sound absorption characteristicsAcoustical Science and Technology, 2005
- Estimation of the absorption performance of multiple layer perforated panel systems by transfer matrix methodJournal of Sound and Vibration, 2004
- Measurement and prediction of typical speech and background-noise levels in university classrooms during lecturesThe Journal of the Acoustical Society of America, 1999
- Potential of microperforated panel absorberThe Journal of the Acoustical Society of America, 1998
- New empirical equations for sound propagation in rigid frame fibrous materialsThe Journal of the Acoustical Society of America, 1992
- The acoustic impendance of perforates at medium and high sound pressure levelsJournal of Sound and Vibration, 1973