Effects of changing the amount of absorption in a computer model of Queen's Hall, Copenhagen, Denmark

Room acoustics modelling is a very useful tool in the design of acoustically sensitive spaces. Auralizations, in particular, are a tangible output that can be used to demonstrate the acoustics of a designed space to non-acousticians. One area of improvement for auralizations is the method of modelling the source directivity. A new method to incorporate source directivity is multi-channel auralizations. An omni-directional source is divided into the number of recording channels and the impulse response (IR) for each channel is calculated. Each individual IR is then convolved with the appropriate recording, and a final auralization is created by mixing all individual channel auralizations together. This study evaluates the objective and subjective effects of using four and thirteen channel IRs in an ODEON model of Queen’s Hall, a hall located in Copenhagen with variable absorption. Analyses of the results reveal great differences in the objective parameters of reverberation time (T30), clarity index (C50), sound pressure level (SPL) and lateral energy fraction (LF80) for each channel’s impulse response across the room absorption variations. Subjective studies were conducted to see the effect on auralizations of changing source orientation in various configurations of the room with different amounts of absorption. The results show that subjects could more easily identify source orientation with an increasing number of recording channels in the auralizations, but a significant effect with absorption was not found. Further studies are being conducted that isolate the effects of varying the amount of absorption on the ease of identifying source orientation.