A trial acoustic improvement in a lecture hall with MPP sound absorbers and FDTD acoustic simulations

Matteo Cingolani, Giulia Fratoni, Luca Barbaresi, Dario D’orazio, Brian Hamilton, Massimo Garai

Research output: Contribution to journalArticlepeer-review


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 (T30) and sound clarity (C50). A systematic comparison with a standard geometrical acoustic (GA) technique is reported as well.
Original languageEnglish
Article number2445
Pages (from-to)1-20
JournalApplied Sciences
Issue number6
Early online date10 Mar 2021
Publication statusE-pub ahead of print - 10 Mar 2021


  • acoustics
  • micro-perforated panels
  • FTD simulation
  • speech intelligibility


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