Including directivity patterns in room acoustical measurements

Abstract

Room acoustical measurements according to ISO 3382 require source and receiver to be of omnidirectional sensitivity. Therefore, radiation patterns of natural sources and receivers (although audible) are not accounted for when using the obtained room impulse responses (RIRs) for room acoustic analysis or even auralization. In order to include this spatial information in the RIR, it is necessary to measure the RIR for each pair of radiation patterns of source and receiver. This could be done by electronic beamforming during the measurement using array systems or by mechanical modification of the transducer (as, e.g., a dummy-head with its corpus). In this contribution, an alternative approach is shown, using the superposition of a set of sequential measurements done with a spherical sound source. At the cost of longer measurement times, the obtained data can be used universally to synthesize RIRs of arbitrary directivity up to a certain maximal spatial resolution, as long as the room is considered as a linear and time-invariant system during the measurement. The measurement device, obtained results, and a study of the validity of the superposition approach are presented in this talk. Based on this representation of the RIR, more advanced spatial room acoustic analysis accounting for arbitrary sets of source and receiver directivity becomes possible.