Seven major U.S. orchestras will have their touring deficits covered for the next four years by a $10 million grant from American Telephone & Telegraph Co.

AT&T Vice President Edward M. Block announced the commitment yesterday at a news conference in New York. The orchestras are the Boston Symphony, the Chicago Symphony, the Cleveland Orchestra, the New York Philharmonic, the Philadelphia Orchestra, the Los Angeles Philharmonic and the Pittsburg Symphony Orchestra.

Other orchestras might be included in future years, said Block. The National Symphony, which was not included, is not currently negotiating for upcoming funding.

Oleg Lobanov, managing director of the National Symphony Orchestra, said, "We knew that AT&T had selected seven orchestras. Each of the seven orchestras have larger (touring) budgets than the National Symphony. But we have been in touch with them (AT&T) about sponsoring a (NSO) concert."

The money, Block said, would be used to cover the difference between the cost of touring and box office revenues. The program, he explained, will include nearly 100 concerts this year and will be augmented with master classes given by principal palyers for students at local music schools.

Livingston L. Biddle Jr., chairman of the National Endowment for the Arts, praised the project as a "pioneering step in corporate support of the musical arts in our country."

AT&T presented conductors Andre Previn of the Pittsburgh Symphony Orchestra and Carlos Maria Giulini of the Los Angeles Philharmonic with silver batons for their contribution to music. The batons will be the symbol of the "Bell System American Orchestras on Tour," a spokesman said.