A New Acoustic Testing Chamber Aids In The Development Of Computer Products

In selecting computer systems and devices for industrial plants, offices, data processing centers, and similar facilities, increasing attention is being given by specifiers and purchasers to the "quietness" of the equipment's operation. Partly this has been in response to existing and proposed government regulations regarding allowable sound levels in the workplace. An equally important concideration has been the growing awareness by managers that a noisy environment can cause worker fatigue, leading to lower productivity and also a greater chance of errors occuring. To better meet this challenge of providing users with products that are not acoustically intrusive, Storage Technology Corpporation (STC), a leading computer peripheral manufacturer, has installed an An-Eck-Oic Chamber having a free field of 9'-4" high x 20'-0" wide x 18'-8.5" deep. This anechoic facility, engineered by Eckel Industries, Inc., is now allowing STC to more accurately evaluate the noise characteristics of its disk drives, tape drives, printers, and other devices.

The acoustic test data obtained in this 120Hz cutoff chamber is used by STC in its design programs to ensure that a product's noise level has been reduced to lower than "acceptable" levels. The enclosure also functions as a useful quality control tool for checking on acoustical performance of products. Even in the short period of time it has been in operation at STC, this anechoic chamber has proved to be quite beneficial to the company. According to Roger Dennet, Senior Quality Control Engineer, the chamber is "a truly working facility, a very utilitarian echo-free room which is being used almost full time." One particularly signifigant result of the studies conducted in the chamber has been STC's development of a quieting kit for tape drives.

Even though this chamber was a custom built one, its cost was very low - about one third the cost of a normal anechoic chamber that size. This economy was achieved mainly by modifying a building and installing An-Eck-Oic wedges within an existing room. That is, the enclosure's walls were in place. However STC has to construct a false ceiling under the existing concrete ceiling of precast concrete "T" sections. The false ceiling provided a flush surface on which Eckel's unique wedge track system could be attached. After these tracks were installed on the ceiling and walls, the wedge lining was put into place. The fiberglass wedges used are 28" deep, 2ft. square modules.

Access to the test facility is provided by two doors, both of which are wedge lined on the chamber side. One is a 4'-0" x 7'-0" rolling plug door, designed to work in conjunction with the 3'-0" x 6'-8" exterior door. The other is a wedge cage door, also 4'-0" x 7'-0". This door is pivoted at an other corner so that the steel wedge cage rotates 180 degrees to provide a full opening into the chamber. The chamber also incorporates a ventilation system with intake and exhaust silencers.