Interior Department Undersecretary Donald P. Hodel has asked Virginia Gov. John N. Dalton for assurance that noise from the planned Dulles Toll Road will not disturb performances at Wolf Trap Farm Park.

Hodel told Dalton in a letter released yesterday that his department is "deeply concerned that, unless the State of Virginia is fully committed to the protection of Wolf Trap Farm Park, significant adverse noise impacts will be experienced both during and after construction by the more than 600,000 people who each year attend performances and events at the park.

"Specifically," Hodel's letter said, "we seek your assurances that the commitment Virginia State Highway Commissioner Harold C. King made to National Park Service Director William J. Whalen on August 2, 1979, that 'The toll road will not increase noise levels one decibel more than currently exists at Wolf Trap Farm Park' be fully honored in both the planning and construction of the toll road."

A spokesman for the state highway department in Richmond said yesterday that planners are "currently in the process of identifying and resolving the problems raised in the letter."

The toll road will run on either side of the Dulles Access Road between Dulles International Airport and the Capital Beltway. The state has yet to set a date for construction of the project, which has been approved by the Virginia legislature.