Acoustic profiling and non linear acoustics finite element modeling of Sugathadasa Indoor Stadium

Abstract

Acoustic performance of an arena is measured and classified by it’s acoustic parameters. The acoustic parameters are used for the designing of the sound systems and improving the arena’s acoustic performance by proper sound proofing. According to international standards DIN EN 18041, sports arena comes under type A5 and can be changed into type A4/A3/A2 education and communication/presentation halls or type A1 musical halls. During our profiling work some of critical acoustic parameters of Sugathadasa indoor stadium were measured and estimated according to the ISO EN 3382 standard. The primary measurement parameters, reverberation time (RT60dB), center time (TS), early energy fraction (D50) and objective clarity (C80) were measured and then are used for identifying and classifying the arena. The arenas also need to satisfy the noise criteria (NC) standards depending on the event that the arenas are used for and also considering the surrounding environment. Generally, the arenas are changed temporarily depending on an event by increasing the acoustic absorption area and various other sound proofing methods. This paper contains acoustic profile, reverberation time, center time, early energy fraction, noise criteria, the sound clarity index measurements of the Sugathadasa indoor arena. Moreover, the acoustic space of the arena was modelled with nonlinear FEA methods taking the Khokhlov-Zabolotskaya-Kuznetsov (KZK) nonlinear wave equation and Timothy Walsh (TW) numerical formulation of the KZK model. Nonlinear acoustic wave equation was used considering the lager acoustic space of the arena and complex structural, geometrical and surface elements of the arena such as steel trusses, columns, beams, diffusers, absorbers, resonators and reflectors. Moreover, to find the best locations for the speaker arrays the acoustic parameters were estimated by exciting the acoustic space with sound sources at selected locations. The locations were selected by using the simulated result of acoustic ray tracing based FE modelling. By using these results best locations for the arena speaker system was determined. In addition to find out the acoustic frequency response of the current sound system, the arena was excited with white noise, pink noise and brown noise audio signals and then the responses were measured by using microphones placed at selected locations