Synthèse de champs sonores par réseaux à haute densité spatiale
Sound field synthesis with high-density loudspeaker arrays (HDLAs) remains one of the main research topics for the Acoustic and Cognitive Spaces team, which naturally finds its applications in musical production. It also represents an outstanding vehicle for the promotion of our developments and the numerous collaborations with other research institutions and prestigious musical creations.
As a part of a research collaboration with Rensselaer Polytechnic Institute, the concert hall in the Curtis R. Priem Experimental Media and Performing Arts Center (EMPAC) was equipped with a large scale HDLA. This new system consists of a linear 512-loudspeaker array (16 modules of 31 loudspeakers associated with a subwoofer) for Wave Field Synthesis (WFS) and a dome of 100 loudspeakers for Higher-Order Ambisonics (HOA). The distance in between the loudspeakers of the WFS array is 5.8 cm. Different geometric layouts were tested; each making it possible to take full advantage of different methods of sound field synthesis. For example, positioning two arrays on top of each other and offsetting them by half the on-center distance between drivers results in a horizontal distance of 2.9 cm between speakers and a total array length of 15 m. In doing so the aliasing frequency can be shifted up to around 6 kHz, which results in a striking impressive holophonic sound field reproduction.
Arranging the speaker modules in a circle, on the contrary, allows for a 2D HOA reproduction of orders up to N=250. The independently controlled loudspeakers are driven by a cluster of computers that compute the sound field synthesis in real-time. One of the major issues in this project was the implementation of multi-zone sound field control.
IRCAM Team : Acoustic and Cognitive Spaces
WFS – HOA system for spatial audio rendering in the Curtis R. Priem Experimental Media and Performing Arts Center at Rensselaer Polytechnic Institute de Troy (US). The system consists of 16 linear arrays of loudspeakers spaced at 5.8cm, configuredhere for bi-dimensional HOA diffusion.