Salle des Princes of the Grimaldi Forum Monaco: Customized acoustics.

Each type of music requires a specific sound environment characterized by, for example, the reverberation time, which is expressed in seconds and corresponds to the time it takes for the sound to die out in a room. For instance, a low reverberation is desirable for theater or lectures, while a longer reverberation rich in low frequencies is appreciated for symphonic music.

The CARMEN system, a French acronym for Active Control of Reverberation by a Natural Effect Virtual Wall, designed and developed by CSTB acousticians, is an electroacoustic system based on the principle of active virtual walls. Thanks to these virtual walls, it is possible to change the reverberation of the room according to the show to reach the ideal acoustics without amplification systems. 

Built into the Grimaldi Forum in 2000, CARMEN modulates the acoustics of the Salle des Princes according to its uses, from conferences to concerts, theater, ballet, electroacoustics, opera or any other event requiring an adapted sound immersion. Its different configurations allow it to be adapted, for example, to common operas as well as to great operas with chorus, to symphonic and oratorio orchestras, to classical or romantic orchestras, with or without chorus and soloists.

It is no longer the artists that adapt their performance to the concert hall, it is the concert hall that adapts to the artists’ performance. This innovative technology immerses musicians, speakers and spectators in an acoustic space that offers the best sound experience, regardless of where you sit in the room. This is made possible by implementing about 30 cells, each consisting of a microphone, an electronic filter unit, a powerful amplifier and a loudspeaker. These cells arranged in virtual walls are distributed on the walls of the room and on the ceiling, the whole being controlled by a digital audio station.

The unique arrangement of the microphones and loudspeakers ensures a completely natural acoustics, in which the spatial and temporal consistency of the sound field is preserved. Reverberation increase is simply achieved by the interplay of reflections between different parts of the virtual walls, in the same way as between real walls. There are no microphones to limit the possibilities of stage use. As a result, the natural directionality of the sound sources and the sound coverage of the stage cannot be altered, as it happens when sound is picked up with microphones close to or above the stage.