The Bologna University team has developed a new method to measure the impulse response IR of three-dimensional 3D spaces. The IR method allows the complete characterization of the sound propagation at the measurementpoint in rooms or in enclosedspaces. The images and videos calculated from the IR represent the direction of the reflection origins of the room, preservedfor the posterity. The method is based on IR measurements withdifferentmicrophone probes. The first probe is made up ofa mono-directional microphone that allows the determination of the conventional mono-aural acoustic parameters, it is considered the "reference" result. The second probe is made up ofa doublemicrophone, it is used for binary or stereo auralization. The third probe is made up of4 microphones in B-format configuration, it is used for Ambisonic auralization. The fourth probe is made up of 32 or 64 compact microphones, fixed on a spherical and cylindrical surface, it is used to measure and to reproduce higher order 3D IR. The combination of these four spatial measurement methods makes the reverberation virtualization possible with the spatial resolution of theatres, opera houses or concert halls. Moreover, itanalyses the origin of all the first reflections with qualitative intensity detail and it represents them with 3D images.
The Bologna University team, in collaboration with the Progetto Sipario, has been developing a listening room composed by different multi-channel sound reproduction systems. The systems arebased on the reconstruction of the acoustic field through several techniques: a bi-pole system, a 32-speakers Ambisonic system, a 160-speakers Wave Field Synthesis WFS. Everything will be managed via PC and MADI audio interface.
The WFS sound spatialization technique reconstructsthesound field with a large number of evenly positioned speakers in a space. The design of 20 modular elements with 8 speakers each is in charge of the ZOTAUDIO team (ex-students of the Parma University). The complete system is made up of a 160-speakers square plus 4 subwoofers. The facility is the reconstruction ofany sound space that has been characterized by IR measurement. An audio track could be added in the space as a virtualsources, with a fixed or mobile position. The listening areais located inside of the square. Each WFSbar is linked at the audio interface with A2B boards. The signals areamplified by the embedded-bar AMP board. Thesubwoofers extend the frequency response of the system to lower frequencies.