Practical spatial acoustic measurements in performance halls with a reduced virtual orchestra

• The article has been revised to more focus on the practicalities of the system and examples of use and clarifications has been made in accordance with recommendations of the reviewers. The Virtual Orchestra has previously been used to measure room acoustic conditions of major concert halls, with the aims of objective comparisons and subjective evaluations through auralization, and to characterize and investigate specific problems in halls. The idea is to simulate an actual orchestra on stage with an array of loudspeakers and then measure the spatial impulse response in the hall with multiple source positions. This approach gives a more complete picture of the acoustic projection and reflection paths between the stage and the audience than traditional measurements with a single omnidirectional loudspeaker in few positions. However, the originally proposed system requires over 24 loudspeakers and is therefore not very convenient for consultants to use from the practical perspective. In this paper a scaled-down version of the measurement system is presented. This system uses a total of 8 loudspeakers and the spatial impulse response is recorded by a standard A-format microphone. The comparison to the original system is presented with spatial analysis results, and the study is accompanied by examples of results and findings achieved with practical measurements in halls.