LENOX, Mass. — Tanglewood officials have announced plans to build an $8 million concert hall on the grounds of Highwood, a Berkshire estate adjacent to the summer home of the Boston Symphony Orchestra.

The new hall will serve as a performance facility for the concerts of the Tanglewood Music Center, the orchestra’s training facility for young professional musicians. The hall also will be used for the Friday evening Prelude concerts, chamber music concerts and recital series.

The new concert hall will be rectangular in shape and will have indoor seating for 1,200. Of 2,000 lawn listeners, 500 will have a good view of the stage.

Part of the costs, $3.5 million, will come from the Tanglewood Music Center’s 50th anniversary campaign, which recently announced it topped a goal of $12.5 million by $400,000.

Officials now seek to raise $2.5 million for the hall by the end of the summer so that construction can begin in March 1991. Completion is scheduled 18 months later.