Bruel & Kjaer Instruments, 121 Keeler Dr., Ridgefield, CT 06877
Room acoustic parameters should describe the subjective evaluation of a room. The most important parameter for evaluation of acoustic comfort in a room is the reverberation time, but additional parameters are necessary for evaluation and design of concert halls and auditoria. Beside of the reverberation time and EDT (early decay time) it is possible from the integrated impulse response to calculate acoustical parameters such as ``early to late sound index'' (clarity), ``early energy fraction'' (deutlichkeit), ``center time,'' and ``total sound level.'' These measurements and calculations are today possible to perform in situ by a sound level meter with application modules connected to a sound source and a lap-top computer; traditionally these measurements required a much bigger measurement system. Therefore, by means of this easy portable instrumentation, the results may be inspected in the field and additional measurements can be done if necessary. During the presentation, the above acoustical parameters are mentioned and measurement results, obtained by instrumentation from Bruel & Kjaer, from a European concert hall and from a hall in the USA are described.