“SIPARIO SOUNDS”: A NEW OMNIDIRECTIONAL LOUDSPEAKER FOR MIMO AURALISATION

SIPARIO is a project recently funded by the Italian region Emilia Romagna. It aims to virtually reconstruct both 3D audio and 360° video of real performances by making recordings and undertaking acoustic measurements inside historical theatres and concert halls spread all over the Europe. One of the most relevant topics of this project is the development of a new spherical sound source, equipped with 32 individually-controlled loudspeakers [1], designed for measuring acoustic characteristics of these performing arts places. This loudspeaker array is capable of simulating the directivity of any dynamic sound source. The loudspeaker can work also like a traditional omnidirectional sound source for measuring standard acoustical parameters, hence it can be used in room acoustics tests in accordance with ISO3382 standard. Finally, it can create super-directive beams of various shapes, with arbitrary directivity patterns such as spherical harmonics (High Order Ambisonics) or cardioids (Spatial PCM Sampling). The Exponential Sine Sweep (ESS) signal has been employed in order to measure the room impulse response (RIR). It is also possible to employ a Multiple Input Multiple Output (MIMO) approach [2] by feeding sequentially the ESS signal to each transducer of the loudspeaker array, while a spherical microphone array is employed for recording. In this paper it is explained how to compute the matrix of FIR filters necessary to process such a MIMO RIR, and to synthesize arbitrary polar patterns for both source and receiver. Moreover, future developments of the new sound source are briefly described in Section 7, including the applications for the specific project.