OAKLAND, Calif. — Oakland International Airport will test California’s first “hush house,” designed to reduce noise from engine maintenance by 15 to 18 decibels, between midnight Sunday and 2 a.m. Monday. Two tests — one inside and one outside the structure — will be conducted for comparison purposes.

Formally known as a ground runup enclosure, the three-sided structure is made of sloping zinc-coated steel “Noiseblotter” panels, creating walls that range from 19 to 40 feet in height.

The hush house, located near the center of the airfield, encloses a 325-by-264 feet rectangular area and is large enough to accommodate Boeing 747 aircraft.

The $4 million facility will be used for testing engines, which must be operated at full power, after routine maintenance or repairs. Not only will the “hush house” reduce engine noise, but it also will allow airlines to test engines in a wider range of engine conditions than is possible on an open field.

The enclosure also can be used for washing aircraft, and will contain aircraft cleaning products through special drains that keep runoff from being discharged into San Francisco Bay.

Oakland is the fourth airport in the nation to build a hush house, expected to reduce noise impact on neighboring communities as well as to allow testing in a wider range of wind conditions than is otherwise possible. Other installations are in Chicago, Portland and Indianapolis. All have been built by Blast Deflectors, Inc. of Watsonville.

“The primary purpose is to accommodate our neighbors, who have been concerned about noise from engine tests needed for safe operation of aircraft,” said Steven Grossman, director of aviation for the Port of Oakland. “It has been discussed extensively with the Airport Community Noise Management Forum, and there is a consensus that it will benefit nearby residents, as well as the airlines.” Tests at a similar enclosure at O’Hare Airport in Chicago showed noise reductions of up to 20 decibels at a distance of one mile from the enclosure.

The enclosure is scheduled to go into use in June following completion of testing and final construction work.

The test is scheduled for midnight because sound typically travels further at night and on Sunday night because it is the time the airport has the smallest number of scheduled flights. The hush house is being paid for from the passenger facility fees levied on all tickets.

Oakland International Airport served 11.4 million passengers and handled more than 600,000 metric tons of air cargo in 2001. Oakland International has more than 200 flights a day on 11 domestic and international carriers to 33 nonstop destinations, including the Hawaiian Islands, the New York City area, Atlanta and Mexico. The airport is a revenue division of the Port of Oakland.

Oakland International is the only Bay Area airport with a dedicated shuttle bus that meets every Bay Area Rapid Transit (BART) system train at the nearby Coliseum station. On-airport parking rates are $18 a day in the long-term lot and $15 a day in the economy and overflow lots. For toll-free information assistance on ground transportation and parking services, call 1-888-IFLYOAK (435-9625) .