PhD defence by Hermes Sampedro Llopis

Title: Reduced basis modelling for accelerated numerical room acoustics simulations

Supervisors
Principal supervisor: Associate Professor Cheol-Ho Jeong, Department of Electrical and Photonics Engineering, DTU, Denmark
Co-supervisor: Professor Allan Peter Engsig-Karup, Department of Mathematics and Computer Science, DTU, Denmark
Co-supervisor: Chief consultant Jesper Bo Andersen, Rambøll Group A/S, Denmark

Assessment committee
Associate Professor Vicente Cutanda Henriquez, Department of Electrical and Photonics Engineering, DTU, Denmark
Professor Gianluigi Rozza, Scuola Internazionale Superiore di Studi Avanzati, Italy
Professor Maarten Hornikx, Eindhoven University of Technology, Netherlands

Master of the Ceremony
Associate Professor Poul G. Hjorth, Department of Compute, Section for Dynamical systems, DTU, Denmark

Abstract
Room acoustic simulations are valuable when designing the acoustic conditions of buildings. The accuracy and efficiency of the simulations are always compromised, commonly leading to a degradation of the accuracy. Moreover, it is common to perform a large number of simulations during the design stage of a building to find the optimal configuration of acoustic materials, e.g., amount, position, properties, etc. This need increases the whole computational cost of the procedure.
This PhD project focuses on accelerating room acoustic simulations performed with numerical discretization methods. The acceleration is obtained by a reduced basis method for room acoustics. The method allows reducing the computations when a large number of simulations are required under the variation of a set of key design parameters of the acoustic materials. The schemes are able to simulate wave propagation in a room with high precision, and speedups of two and three orders of magnitude are found for 2D and 3D domains, respectively.
The framework is extensively analyzed under different conditions, including complex reduced-order models. Moreover, a listening test is conducted to better understand how the compromise between accuracy and acceleration behaves in terms of perception.
Furthermore, the reduced basis method is incorporated into a proposed acoustic virtual reality system that couples acoustic simulations with virtual reality, allowing one to experience the simulation results in an immersive and intuitive way that helps to communicate with architects, engineers and stakeholders. The method is tested with a proof-of-concept modelling of an existing room.