Holosonics have a very narrow footprint and narrow bandwidth. Okay for voice delivery to a single visitor. Typically I would recommend footprint decals on the floor to tell visitors exactly where to stand. Even a foot left or right changes the quality of the sound, which is not great to begin with. I do not recommend for music, or anything where the music is important, or even for baritone voices as they have no low end. This is typical of directional speakers since lower frequencies are not directional.
I prefer Dakota speakers for narrow beam directional. Still highly focused but a larger footprint with controls for beam width and slightly better fidelity. Can serve two people side-by-side.
Brown Innovations has an array of directions solutions from domes (highly focused) to narrow focus. Domes can provide stereo at higher bandwidths (music). I prefer narrow focus speakers with careful volume control rather than highly focused "beams" like Holosonic and Dakota. Beams serve a purpose, but jumping immediately to highly focused speakers ignores many more important factors. Physical acoustic control (spacing, barriers, absorption, proper volume control) should be the first concern. Some controlled spill is important to "energizing" a space so it does not feel like a cathedral. While you may want an art gallery to be silent as a tomb, most museums benefit from the "what's that over there" effect. If you do want the cathedral effect, I recommend hand-held audio and/or headphones.
Recently we swapped out holosonics in a design for JBL Control 67Hc speakers which are narrow beam pendant speakers. The client wanted pools of sound, not visitor isolation. We considered Dakotas but decided that even these were overkill. The JBLs are designed for high ceilings but can be used for close listening and will provide enough control in our environment to mitigate spill from one exhibit to another without sacrificing fidelity.
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Tod Hopkins
Museum Media Specialist
443-472-5978
tod@hoptod.com------------------------------