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Audio Technology Transforms Museums

Jun 1, 2009 12:00 PM, By Dan Daley

Integrating sound into modern displays calls for innovative solutions.


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Focused-beam audio systems help localize audio to a particular exhibit. Dakota Audio
FA 501 arrays and the smaller MA 4 arrays are field-adjustable for mounting height and pattern width. Even with the adjustability, the audio beam needs to precisely positioned.

Focused-beam audio systems help localize audio to a particular exhibit. Dakota Audio FA 501 arrays and the smaller MA 4 arrays are field-adjustable for mounting height and pattern width. Even with the adjustability, the audio beam needs to precisely positioned.

That same technique is used near a large inverted cone of images, where the arrays were aimed for that same 4ft. to 6ft. target—about the height range of the heads of adults and children—and then the height of the space itself dissipates the audio before it can reach a reflective surface.

In other instances, conventional loudspeakers could be used, such as the Tannoy i5 loudspeakers, which were also floor-mounted around larger exhibits. The ex¬hibits used EAW DX810 DSP units for delays to match the audio to the picture displayed on large screens. But with all the floor-mounted loudspeakers, the positioning was critical because the forms and the cable troughs needed to be in place and precisely positioned before the concrete was poured.

"The floor was the best place to put speakers of any kind to get the sound as close as possible to the visitor," Kidd says. "But it was a huge project-management proposition. We had to determine from the plans where the speakers needed to go, and then we only had a few days to line them up exactly with tape measures and lasers. If it went in wrong, there would have been no way to fix it."

Timely exhibit

At the Museum of Chinese in America, which is scheduled to reopen June 26 in New York, VideoSonic Systems president and CEO Glenn Polly used several types of focused-beam loudspeaker solutions for various facets of the installation. In a timely exhibit about how interrogation techniques were used on Chinese immigrants at the turn of the 20th century, a chair is set up with a display in front of it, allowing the user to determine the intensity of a faux interrogation, accompanied by concomitantly more intense sound effects. Since the levels of the audio will vary according to each user's tolerance, and since the exhibit is nearly adjacent to another, the sound had to be highly localized. VideoSonic used Holosonics' Audio Spotlight focused-beam loudspeaker directly overhead.

For the five stations where images of immigrants are accompanied by their audio narratives, the company used Dakota Audio FA 501 units placed directly above each station with a motion sensor that triggers the audio program to minimize the footprint of each station. The choice, Polly says, was dictated by the content.

"The Holosonic speaker is significantly more intensely focused, but the nature of how it does it does not lend itself to full-frequency audio, and the portrait narratives have both spoken word and music, for which the Dakota speakers are a better fit," Polly says. "Not quite as tight a focus, but with a fuller frequency range."

Also adding to the ability to fine-tune the loudspeaker focus is the fact that the audio and the video signals run on Cat-5 cabling, they are controlled and routed by a Crestron QuickMedia system, and they are digital until just after the DSP stage of that system. The system then applies various types of equalization (graphic and parametric) for each endpoint in the museum.

"Frequency is another way to control the directionality of the sound," Polly says. "We can also compensate to some degree for any acoustical issues at that point, and we can add resolution with the tone controls that can let us, for instance, add midrange and high end to a recording with scratches and other artifacts."

In this case, the larger message is that while it's about focusing the sound, it's also about making sure the content is easily heard. Bad sound can distract listeners, and they lose focus that way.



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