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impaginato corretto fullone_Layout 1 13/10/15 12.08 Pagina 13 Department of Engineering, ICT and Technologies for Energy and Transport Patent Title Title Process and apparatus of a multichannel audio Process and apparatus of a multichannel audio system for active playback of acoustic quadraphonic system for active playback of acoustic quadraphonic sound events. sound events. Ref. CNR 1888 Ref. CNR 1888 Assignee(s): CNR CNR Institute: IDASC Main Inventor: Domenico Stanzial Countries: IT Priority date: 06/03/2008 Abstract Abstract The invention defines the process and the equipment needed for playing back quadraphonic sound. This The invention defines the process and the equipment needed for playing back quadraphonic sound. This process is done via an electro-acoustic device called “quadraphonic player”, capable of performing the process is done via an electro acoustic device called "quadraphonic player“, capable of performing the feed-forward active control of sounds. The reproduced sound is generated from one or more speakers feed forward active control of sounds. The reproduced sound is generated from one or more speakers fed by suitable electrical voltage signals, measured and calculated by the device itself. The sound from fed by suitable electrical voltage signals, measured and calculated by the device itself. The sound from the quad-player is automatically adapted to the acoustic characteristics of the listening room in order to the quad player is automatically adapted to the acoustic characteristics of the listening room in order to reconstruct, optimally, according to an algorithm based on least squares, the original sound event (virtual reconstruct, optimally, according to an algorithm based on least squares, the original sound event (virtual acoustics). acoustics). Background Background The invention constitutes the final ring of the chain that begins with the recording process (patented) of a The invention constitutes the final ring of the chain that begins with the recording process (patented) of a quadraphonic “sound event”. This is identified with the set of the four audio tracks corresponding to the quadraphonic "sound event“. This is identified with the set of the four audio tracks corresponding to the sound pressure signal and the three components of the velocity signal of the air particle. sound pressure signal and the three components of the velocity signal of the air particle. Technology Technology The invention refers to the application of sound intensimetric techniques for multichannel recording and The invention refers to the application of sound intensimetric techniques for multichannel recording and playback systems. The technology foresees the use of pressure-velocity probes with high-fidelity audio playback systems. The technology foresees the use of pressure velocity probes with high fidelity audio quality and active speakers able to control the acoustic impedance at the listening point (sweet spot). quality and active speakers able to control the acoustic impedance at the listening point (sweet spot). Advantages and Applicatons Advantages and Applications The quadraphonic player allows to achieve the highest accuracy in the reproduction of the sound, even in The quadraphonic player allows to achieve the highest accuracy in the reproduction of the sound, even in rooms acoustically very different from the original. It is able of reproducing single-point recorded sound rooms acoustically very different from the original. It is able of reproducing single point recorded sound event (perspective quad-playback) and multi-point recorded sound events (holographic quad-playback). event (perspective quad playback) and multi point recorded sound events (holographic quad playback). Main applications are in the fields of acoustic virtual reality, artistic audiovisual performances and music Main applications are in the fields of acoustic virtual reality, artistic audiovisual performances and music production. production. Development stage Development stage The invention is currently at the stage of “proof of concept” and was realized experimentally only in 1-D test The invention is currently at the stage of “proof of concept” and was realized experimentally only in 1 D environments. For its prototyping one requires instrumentation not yet developed both in the test environments. For its prototyping one requires instrumentation not yet developed both in the 13 recording phase of the sound event (hi-fi p-v probes) and in the playback (active control speakers of recording phase of the sound event (hi fi p v probes) and in the playback (active control speakers of acoustic impedance). acoustic impedance).