FEATURE: DIRECTIONAL AUDIO
Active Audio's SA250P StepArray column loudspeaker at Le Carrousel de Louvre, Paris – this uses the DGRC principle, which can be regarded as a beam-shaping technique Below: Illustrating the DGRC principle
is used to indicate that the loudspeaker radiation pattern can be adjusted in such a way that multiple main lobes are created – in most cases, two main lobes, for instance aiming at the main floor and the balcony of a theatre,” says van Raalte.
This ability to target specific
areas is crucial. Beam splitting generally means that “upper and lower beams in a column line array can be individually configured and controlled, enabling separate room areas to be more effectively targeted”, says Uli Haug, executive director sales & marketing, Fohhn Audio. Integral to making this technique work is that the array be long enough and comprised of enough drivers “so that above a certain frequency, it is possible to create more than one source, each of which can then be beam-steered”, says Baird. In contrast to other beam
control approaches, there has been some controversy over the language associated with beam splitting. Berger, for one, remarks that the term “has been used by some manufacturers (mostly incorrectly) to describe a coverage pattern with a distinct lobe in the main coverage area that creates the illusion of separate beams”.
A NATURAL PROGRESSION Although the specifics of beam control are evidently the subject of much variation, their underlying motivation is fairly uniform and should be seen in
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the context of the ongoing pursuit of achieving the best possible coverage in acoustically problematic environments. “System designers and acousticians spend countless hours in this pursuit,” observes Berger. “The ability to digitally manipulate the directional characteristics of a loudspeaker system benefits their cause in several fundamental ways.” Heightened directivity and
greater freedom in positioning the speakers has made beam control products popular choices for all manner of install applications – with the most frequency cited including airports and railway stations (notoriously affected by unforgiving RTs), shopping malls, houses of worship and theatres. As for the future of beam
control… Well, that’s likely to “mean more concise control and flexibility, as well as taking beam steering into higher SPL
applications”, predicts Graham Hendry, VP of application engineering and training, TC Group. “Because the application [involves] higher SPL doesn’t mean the physics of beam steering can change. Sources still need to be densely spaced and have independent amplification and control to allow the best performance, acute angles of steering, and fuller frequency control.” With modern architectural
practices often favouring materials that make intelligible
sound more – not less – challenging to deliver, it is to be expected that beam control technologies will become evermore prevalent as integrators address the difficulties of acoustically hostile built environments.
www.activeaudio.fr www.ateis-europe.com www.boschsecurity.co.uk www.duran-audio.com www.fohhn.com www.martin-audio.com www.meyersound.com www.tcgroup.tc www.vueaudio.com
September 2013 33
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