Tech & Learning - June 2008 - (Page 44)

FEATURESTORY Installation foreman Larry Hudgins has his hands full overseeing the installation of the Granite School District’s 1,500 classrooms with soundfield and projection systems. PHOTO BY MARTIN VAN HEMERT dents better comprehension and retention in the classroom. Although a school may be tempted to use assistive listening devices for everyone in the back of the room, those devices aren’t the most practical solution. A better choice, one that is readily available, is a soundfield system. Russell Gentner, president of Listen Technologies Corporation, explains the difference between a soundfield and an assistive listening system: “An assistive listening system typically uses a microphone and portable transmitter worn by the instructor. Systems can be either RF (Radio Frequency), such as FM, or IR (infrared). The portable transmitter sends an RF or IR signal to portable receivers worn by hearing-impaired individuals. These individuals get direct sound in their ears via headphones, earbuds, or inductive neckloops, and those individuals can directly control volume, etc. with a remote control. A soundfield also uses a portable transmitter and a microphone worn by the instructor, and it can also be either RF or IR, but it sends its signal to a central receiver and then to several loudspeakers in the room. This effectively provides a sound reinforcement system, adding 3 to 6 dB of gain, which dramatically improves the signal-to-noise ratio in the room.” See Figure 1: Basic Soundfield System Block Diagram. Should you select RF or IR for your class? “RF systems were used for several years and are a good technology, but “ RF systems were used for several years and are a good technology, but may not serve the purposes for students because of the large number of classrooms in a confined space. may not serve the purposes for students because of the large number of classrooms in a confined space,” says Tom Dobson, vice president of sales and marketing at Audio Enhancement. The problem with RF systems is not in their quality, it’s the potential for interference. An RF-based system works anywhere, but can be heard in locations outside the classroom and can be affected by other transmitting devices. An IR system does not interfere with systems in adjoining rooms, and does not receive interference from other systems. In 1997, Audio Enhancement took out a patent on the use of IR in the classroom, and, in 1999, the company came to market with the first IR soundfield system. “This technical breakthrough was the true catalyst of the market that we have today; without it the use of sound in the classroom would still be relegated to a special education application, where limited numbers of systems can be used,” Dobson says. The main downside of infrared is that it is adversely affected by strong light sources. If you install an IR system, be sure to note how sunlight will enter the room during different times of the year, “and don’t put the receiver on the ceiling between the projector and screen!” Hogerson says. “We’ve had service calls to fix a non-working IR system, only to find the receiver getting blasted with light from the projector.” ” 44 | TECH & LEARNING

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Technology & Learning - June 2008 Contents Editor's Desk News & Trends They Said It: What Tech&Learning Insiders Are Writing Online Junket Justifiers Back Office Business Students of the World Unite! Get Small for Fall Summer Reading for School Leaders They Can Hear You Now What's New - NECC Highlights and More Leader of the Year Profile

Technology & Learning - June 2008

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