FEATURE: DIRECTIONAL AUDIO
CAL BOOSTS SPEECH INTELLIGIBILITY AT ITALY’S SESSA AURUNCA CATHEDRAL
The dual desire to combat a highly reverberant environment of stone and tile, and to improve all-round speech intelligibility, prompted the recent installation of Meyer Sound’s CAL column array loudspeaker at the early 12th century Sessa Aurunca Cathedral in Italy. The new sound system features
two CAL 32 main loudspeakers to cover most of the congregational seating area. Beam spreading and beam steering technologies (adjustable to a single degree of vertical dispersion) allow the CAL systems to focus acoustic energy precisely on the audience, with minimal energy affecting the adjacent hard surfaces. Both CAL 32 loudspeakers are mounted flush against a side wall to minimise visual impact, with vertical beams tilted down 10º. The vertical dispersion angle is set at
for the shape of the beam to be optimised “with respect to the listening plane on the ear level and the mounting position of the array”. Examples of products working along these lines include both ranges of Active Audio column loudspeakers, incorporating the DGRC (Digital and Geometric Radiation Control) principle, “which can be seen as a beam shaping technique. With DGRC, a large number of drivers can be assigned to a much smaller number of electronic
30 September 2013
30º in order to project a uniform wedge of highly intelligible sound on the seating area. The system design was devised in collaboration between Lorenzo Benigna and Giovanni Bugari from Linear Sound, and consultant Adriano Conte. The system was tuned by Bugari and Meyer Sound Technical Support using the SIM 3 audio analyser. The improvements in audio quality are said to be substantial. “CAL is an exceptional system with superior performance not just for speech, but for music as well,” says Benigna. The new design also features eight Meyer Sound MM-4XP and four MM-4XPD self-powered loudspeakers as discreet spot-fills behind the main speakers, and as fills for acoustically shadowed seating.
channels,” says Meynial. Duran Audio is another exponent of beam shaping in the form of its DDS (Digital Directivity Synthesis) technology, incorporated into the AXYS Intellivox range – the most recent additions to which are the DSX series products.
BEAM SPLITTING The third and final of the commonly encountered beam control approaches is beam splitting. Once again, the clue is in the name. “The term ‘beam splitting’
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