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Help for Hearing : Infrared Sound Transmission Proves a Boon in Concert Halls

September 21, 1986|RANDY LEWIS | Randy Lewis is a Times staff writer.

To most people, the idea of wearing headphones at a live concert or play might seem as superfluous as carrying a TV set to a baseball game. But for many with hearing impairments, the availability of headphones at the Orange County Performing Arts Center could be the difference between a dull aural blur and a satisfying musical or theatrical experience.

The headphones, to be offered at no cost, are part of an infrared sound-transmission system that in recent years has made theatrical and musical presentations more accessible to those who are hard of hearing.

"It's a means of communicating without wires or cables with people who have been issued an infrared receiver," said Paul Magil of Paul Alan Magil & Associates, the Costa Mesa-based firm that is the center's sound and video consultant. "The earphones are lightweight and comfortable, and the infrared transmitter panels are largely concealed within the walls."

The technology of infrared sound transmission was developed in the mid-1970s, originally for home, medical and educational uses; it was adapted for musical and theatrical applications around 1980.

Here's how the system works: Sound from performances is picked up by microphones that are part of the house sound system, converted into infrared light waves and beamed throughout the theater from light-emitting diodes (LEDs) in special panels located along the walls. The signals can be picked up at any location in the theater by miniature receiver-headphone sets that convert the infrared signals back into sound. Volume can then be adjusted by each user without disturbing the person in the next seat.

Infrared equipment for the hearing-impaired is used in nearly 100 major theaters and performing arts centers throughout the country, including the Los Angeles Music Center, the Metropolitan Opera and Avery Fisher Hall in New York, and the John F. Kennedy Center and National Theatre in Washington, said Kathleen Burke, West Coast representative for Sennheiser Electronics Corp., the leading manufacturer of commercial infrared systems.

Infrared equipment has been available in the Dorothy Chandler Pavilion, the Mark Taper Forum and the Ahmanson Theatre since 1981, said Burke, who worked with the Los Angeles Music Center and the Orange County center to enable concert-goers with hearing impairments to enjoy performances.

According to L. A. Music Center research, an average of 55 people use headphones during a performance. About 75% of them are hearing-impaired; the other 25% use the system not because of hearing disabilities but because they feel "it improves the sound," a Music Center spokeswoman said.

The infrared transmission system at the Orange County center is similar to that at other performing arts facilities. But where many older theaters have incorporated infrared sound systems by using portable transmission panels, the center's system is built-in and will, therefore, be unobtrusive, Magil said.

The only visual evidence that the system is operating will be a low-intensity light on the transmission panels, Magil said.

Perhaps the greatest advantage to infrared technology is that it gives people who are hard of hearing the freedom to sit anywhere.

"This system covers the entirety of the seating area, so the hearing-impaired need not be grouped together," Magil said.

Although the infrared system will be used initially only for those with hearing disabilities, it can be adapted for bilingual and even multilingual uses. Theoretically, headsets could be made available for translations in several languages.

"It would not be a major problem, with electronic modification, to adapt it for more than bilingual presentation," Magil said. "On a full-blown system a multichannel receiver would allow a user to select from up to eight channels. It would use the same panels in the wall. We'd just have to change the electronics."

Now, however, it is a single-channel system, which means that the headsets offer monophonic sound only. The system has a frequency response of 50 to 8,000 cycles per second, or as expressed in hertz, 50-8,000Hz. The range of human hearing is 20-20,000Hz, although few adults, even those without hearing impairments, can detect frequencies above 10,000Hz.

"Right now the system is configured for one channel, so the primary thrust is for the hearing-impaired," Magil said. "The undeniable alternative use is for a second language, and there is still the capability for expansion and enlargement of the electronics."

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