AV Technology - May 2008 - (Page 36)

Enhancing Audio in the Classroom ➤ BASIC SOUNDFIELD SYSTEM BLOCK DIAGRAM DVD COMPUTER SOUNDFIELD RECEIVER MICROPHONE SPEAKERS PRESENTER PARTICIPANTS 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-tonoise 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 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.” The main components of a soundfield system are the teacher’s microphone and transmitter, a receiver, an audio amplifier, and multiple loudspeakers — “a minimum of four is needed,” says Hogerson — strategically placed around the room. The goal is to get consistent levels of audio no matter where a student is sitting in the room. Other multimedia products such as DVD players or computers are also connected to the audio amplifier. The best option for the teacher’s microphone is a head-worn or neck-worn unit that keeps a microphone element next to the mouth at all times. This allows the teacher to 36 | AV TECHNOLOGY | may 2008 http://www.hallresearch.com

Table of Contents Feed for the Digital Edition of AV Technology - May 2008

AV Technology - May 2008 Contents Precedent Corporate: How to Qualify an AV Supplier Education: Working Smarter AV Technology's Guide to Networked AV Government: IPv6 — Why You Should Care Calculating ROI on Your Digital Signage Investment Enhancing Audio in the Classroom Minimizing Equipment Theft Smart AV The Tribe Has Spoken AV Enables Interactive Research AV Image Enhancement Product Spotlight Tech Horizons Product Review New Products AV MO

AV Technology - May 2008

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