Staying Focused

Focused-audio products are leveraging digital signage growth and other trends to break out of their niche status. Tim Kridel looks at where the technology is headed. The world is a noisy place, and it’s getting noisier. One reason is the proliferation of multimedia advertising, such as digital signage in mall kiosks and grocery store checkout lanes. That can create a snowball effect, as one advertiser cranks up its volume to try rise above the din.

Those trends and problems are helping expand the market for focused audio products, which project a beam of sound that covers a much smaller area – say, a few square meters – than a conventional loudspeaker. Also known as parametric speakers, these products have been commercially available for years but only recently have begun to break out of their niche status.

“The market for focused or controlled disbursement speakers had been primarily limited to the museum and exhibition markets,” says Glenn Polly, owner of VideoSonic, a U.S.-based integrator that has been working with focused audio for more than 20 years. “But we are seeing an increased demand for this type of product in the digital signage and kiosk markets.”

Some of the new demand is coming from environments that traditionally are relatively quiet but where people now expect to be entertained. Those highlight the main appeal of focused speakers: Striking a balance between the different needs of people in the same room.

“We are also a lot of activity in the doctor/dentist/eye-care waiting room areas, where it is becoming more common to see television ‘edutainment,’” says Dr. F. Joseph Pompei, founder and president of Holosonic Research Labs, which makes the Audio Spotlight system. “Normally the staff (and some customers) cannot tolerate the repetitive noise, but using Audio Spotlight technology, only those wanting to hear the sound, hear it. Hair salon chains are now using our systems to provide individualised sound (TV/music) per seat, and this market is expanding.”

For some applications, focused audio is appealing because it eliminates the need for headphones, such as at a kiosk where people can sample songs before buying the album. That in turn eliminates concerns about germs being passed from one headphone wearer to another, or having the headphones stolen.

The ear of the beholder

The basic concept of focused audio dates back to at least the 1960s. Then and now, the technologies to achieve the effect have varied significantly. Some products use a transducer that produces ultrasonic frequencies.

“Audible sound is being created wherever the ultrasound exists,” Pompei says. “In the Audio Spotlight, the ultrasound exists in a long, thin column, so sound is created throughout the entire ultrasonic beam. This is acoustically equivalent to a very long perfect end-fire array. All of these sources are in phase only along the axis of propagation, and therefore they constructively interfere only in that direction, resulting in an extremely sharp beam, with no side-lobes.”

For more details about how exactly ultrasonics achieve their effect, see https://holosonics.com/technology.html. Other products – such as Panphonics’ system – have an electrostatic design. Each approach affects how tightly focused the beam of sound is. For example, Holosonic says a single step outside of its beam reduces the sound level by 90 percent.

Regardless of the underlying technique, over the past two decades, the selection of focused-audio products has grown, giving integrators more design and installation options. Meanwhile, the dynamic range has increased, making the products suitable for more than just spoken-word applications such as describing a sculpture in a museum.

“Back in the late ’80s, VideoSonic did the systems integration for a ‘hands-on’ children’s museum,” Polly says. “At the time, there was one product available, called the Sono Beam, which was a clear Plexiglas dome, approximately 30 inches in diameter, with a pineapple-shaped speaker that was suspended below the dome. The sound energy would emit from the suspended element and bounce off the parabolic surface of the dome’s interior, providing a contained listening area for the visitor.”

Although the system did its job, it had limitations that many current products have overcome.

“The speaker worked well for voice narration content, but that was it,” Polly says. “The speaker was monophonic and had very limited dynamic range. The speaker needed to be suspended at a certain height to be most effective, and was not very attractive, with the appearance of an old-fashioned hair dryer.”

In some cases, integrators have devised their own focused-audio systems rather than buying off-the-shelf products. For example, when VideoSonic wasn’t satisfied with the fidelity of commercial products, it fashioned one out of lengths of Sonotube (www.sonotube.com), a rigid cardboard tubing that’s used to create concrete foundations. It lined the Sonotube’s interior with fibreglass insulation and then installed an 8-inch Tannoy Dual Concentric driver at one end.

“With this set-up, we were able to achieve high-quality sound and control the dispersion of the speaker,” Polly said. “The only problem is, a high ceiling was required. We experimented with folding the tube at 90 degrees, using the length of Sonotube horizontally and bouncing the sound off of a hard surface inside of the tube. It was not as effective as the tall vertical configuration.”

Today’s products typically address concerns about aesthetics, such as the dome that some systems require. Some vendors, such as Brown Innovations, tuck their driver in blocks of upscale hardwood. Mounting options also affect aesthetics.

“Brown’s can be suspended form aircraft cable or mounted to wall to a post using an mounting arm,” Polly says.

Aesthetics aside, today’s dome-based systems still have a few trade-offs.

“The dome speakers did a very good job of focusing and controlling the sound dispersion using a parabolic reflection principle, but you could not escape the sound of the plastic dome,” Polly says. “There is a harshness to the sound reproduction that the dome creates.”

Some focused-audio products take a different approach, affecting aesthetics and installation options in the process. One example is Dakota Audio’s Steered Array.

“It is a flat panel approximately 36 inches by 36 inches and 3 feet deep, with about 100 tiny speakers installed in a unique pattern,” Polly says. “The speaker can be installed flush into a ceiling and not only focuses the sound into a tight pattern, it also sounds really good. Dakota Audio has several models of this speaker available, [including] a 24 inch square designed to replace a 2 foot by 2 foot ceiling tile.”

Expanding Markets

Besides an expanded range of products, focused audio also is becoming more widely deployed simply because more integrators have more experience with the systems.

“The technology, while once radical-sounding, has now matured to a point where it is now trusted in important installations, and the large set of public references we have, as well as our solid reputation, helps us obtain trust from new clients,” says Holosonic’s Pompei.

Although the digital signage boom is helping drive the market for focused audio, some vendors and integrators say adoption also is growing because advertisers and other companies increasingly view sound as both a problem and an opportunity.

“More clients are realising that sound is an important component of an overall marketing message and that noise from traditional loudspeakers is a real problem in shared environments,” Pompei says. The combination of these aspects naturally turns them to the Audio Spotlight technology.”

Although the market is growing, some vendors have dropped out. For example, American Technology Corp. (ATC) says the HyperSonic Speaker (HSS) side of its business has been “pretty quiet.” Now the company is focusing on other audio products, such as its Long Range Acoustic Device, which is used in the military and law enforcement markets as a sort of acoustic water cannon.

“That’s where the focus of the company has been for the last 2½ to three years and where we foresee it staying for the next two or three years, if not longer,” says Robert Putnam, ATC’s spokesman.

Know the environment

When it comes to design and installation, focused-audio products have a few key considerations. One is the room’s acoustics.

“Sound areas should basically be ‘dead,’ containing as few hard surfaces and as much absorption material as possible to keep the sound from reflecting off of the hard surfaces,” says VideoSonic’s Polly. “The more you can do to isolate the sound areas, the better.”

Flooring is another factor that sometimes is overlooked.

“When a person or group is standing under the speaker, they will absorb the sound,” Polly says. “When no one is present, the sound will bounce off the floor and will travel. It’s a good idea to put carpet or a rug on the floor.”

There’s a side benefit of using a rug. If the speaker design is discreet, such as no plastic dome, then people might not know where to stand to get the full effect. Put a footprint on the rug ensures that they’ll stand in the system’s sweet spot.

In some installations, it’s common for the room to be reconfigured periodically, such as a retail store that moves racks and displays each season. As a result, the focused-audio system might need to be moved accordingly. If so, then it’s worth considering a system that’s easily moved, either by the integrator or even the end user.

“In the case of changing layouts in retail environments, re-aiming the sound is as simple as re-aiming track lighting,” Pompei says, referring to Audio Spotlight.

Yet another design consideration is the content itself.

“Since the sound footprint is designed to be as tight as possible, in any area where a customer is likely to walk through quickly, the message should be short, ear-catching and succinct,” Pompei says. “In areas where customers are more likely to linger – a coffee bar, for example – a longer message can be used.”

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