A multi-engine aircraft (20) includes first and second gas turbine engines (10', 10") for providing motive power to the aircraft, each of the first and second engines (10', 10") comprising an air system (27, 29), an air pressure line (26) extending between and fluidly connecting the air systems (27, 29) of the first and second engines (10', 10"), and a pressure wave damper (31) communicating with the air pressure line (26) extending between the first and second engines (27, 29).