Acoustic design approach for ensuring low frequency balance in musical instrument study rooms: A case study

Abstract

In musical instrument study classes, it is important to establish a balance between frequency bands to ensure acoustic comfort. Porous absorbers generally used in the room, air absorption also shorten the reverberation time in the mid and high frequency bands, but the reverberation time in the lower frequency bands is usually longer compared to mid and high frequencies. In order to balance the lower frequency band, the reverberation time values should be reduced; Helmholtz resonator panels may be preferred to increase the absorption at low frequency bands. The room’s eigenvalues and eigenfunctions were determined by the aid of a computer software (ANSYS 2023 R1 Modal Acoustic Module) that uses the finite element method. Helmholtz panels suitable for the mode frequencies have been designed and mounted in the high-pressure regions seen in the mode shapes. In order to determine the success dimension of the design, ISO 3382-1 parameters, ISO 18233 room response curves and FEM simulation results obtained as a result of measurements made at 26 measurement points before and after the arrangement were compared. It was found that the use of panels provided optimum reverberation time values in the 125 Hz and 250 Hz octave bands according to the BS EN ISO 23591 standard, and that there was a significant improvement in the 63 Hz octave band. Hence, the distribution of sound in the space was improved according to the results obtained for the 26 measurement points.