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Ballpark Audio: A Look At Several Recent Sound Design Approaches

Distributed systems place the loudspeakers much closer to each listener.

The recent kickoff of the 2010 baseball season sees most Major League Baseball teams playing in purpose-built stadiums commissioned in the past 15 or so years, all offering top-end production systems, sound reinforcement among them.

Even venerable ballparks like Wrigley Field in Chicago and Fenway Park in Boston sport venue-wide audio systems implemented within the past few years.

Stadiums present two primary sound design choices. One is the classic “main cluster” approach, where coverage to most/all seating is supplied by a single grouping of loudspeakers in the outfield.

The other method is a distributed system where hundreds of smaller loudspeakers are mounted throughout the seating areas, with each loudspeaker assigned to cover a specific, nearby area. There are also hybrid designs combining both, usually a main cluster augmented by smaller loudspeakers covering severely shadowed regions.

“When evaluating a building plan, the first thing we look at is the geometry of the facility. The venue’s layout and physical attributes help determine the direction, of course, in combination with the client’s preference of direction,” says Ron Baker, senior designer for WJHW of Dallas, which has done the lion’s share of stadium system designs over the past 20 years.

“In the case of a distributed system, there needs to be sufficient surfaces and locations where loudspeakers can be positioned to adequately cover the spectator seating area.”

The vast majority of modern stadium sound designs are distributed, even though the main cluster approach is generally more economical than its counterpart because it requires far fewer components and less installation labor. Distributed systems place the loudspeakers much closer to each listener.

Target, Field, the newest Major League Baseball park, offers a distributed system that incorporates components from several Harman Professional companies.

Frequency response is much broader, so music has more dynamic “punch,” while sound arrival (delay) times are usually dramatically reduced. Further, delay times are typically less than 0.2 seconds, significantly improving the situation for on-field performers in addition to better matching images on the stadium’s video screen(s).

A distributed system also provides an increased degree of control over sound. Portions of the system can be turned off when not needed, or different program sources can easily be directed to difference areas of the venue. The bottom line is improved control and flexibility over the entire production.

Improved smaller loudspeaker technologies developed by manufacturers who focus on the stadium market have helped fuel the distributed trend, along with rapid advances in digital signal processing (DSP) and system monitoring and control. Robert Rose, senior consultant with Acoustic Dimensions of Dallas, notes, “In general, DSP supplies greater control and precision for every single loudspeaker in a distributed system.

It’s also much easier to transport audio signal and control data around the facility to several equipment rooms that are established in several locations in a stadium for a distributed system.

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