A simple acoustic immersion index for music performance spaces

Abstract

A simple acoustic immersion index is proposed that compares the reverberant sound pressure level with the prompt sound pressure level, including both direct and once-reflected contributions, for organ music in a hall defined only by its geometrical dimensions and reverberation time. Two versions of the index are considered. In the first version a very simple calculation is proposed that gives a constant index value S1 throughout the hall. The second version of the index separates direct and once reflected sound, with the result that the computed index S2 varies from the front to the rear of the hall. Values of the index S1 are given for several well known halls and are all close to 0 dB. The exact values appear to correlate well with subjective observations on the acoustical character of the halls.