Time domain large-scale finite element sound field analysis of a multi-purpose hall

The authors have been developing Large-scale Finite Element Sound Field Analysis, or LsFE-SFA for short, to analyze sound fields in architectural rooms with complicated boundary conditions. The main purpose of this paper is to show its applicability and accuracy when a realistic large-scale sound field is to be analyzed in the time domain. A multi-purpose hall (A-hall, for short) with the volume of more than 37, 000 m³ and about 2, 500 seats is analyzed hereafter. At first, both mathematical basis of time domain LsFE-SFA is explained briefly. Then, both frequency and time domain LsFE-SFA were applied onto the sound field in A-hall. In the analyses, two types of boundary modeling, with or without balcony, were given into the computations. The values of absorption coefficient of materials except auditorium side-walls were given by referring literatures, and that of side-walls were given by in-situ measurement following some of the authors' EA-Noise method. By the frequency domain LsFE-SFA, sound pressure level distribution contour maps at 63 and 125 Hz were computed and the results were confirmed to be good. Then, the 1/3 octave band filtered impulse responses centered at 63 Hz and 125 Hz were computed by the time domain LsFE-SFA, and fair agreements with measured data were found. Finally, the results by the time domain LsFE-SFA were transformed into the frequency domain and the relative sound pressure level distributions of them showed excellent agreement with those computed by the frequency domain LsFE-SFA directly.