A multi-mode powertrain system is described, and includes an internal combustion engine and electric machines operative to transfer mechanical power through a gear train to an output member coupled to a driveline, wherein the electric machines electrically connect to a battery. The method includes determining an audible noise-based maximum engine speed, wherein the internal combustion engine generates an audible noise that is less than a threshold noise level when operating at a speed that is less than the audible noise-based maximum engine speed. The electric machines and the internal combustion engine are controlled responsive to an operator torque request including controlling the engine speed to be less than the audible noise-based maximum engine speed when battery power is greater than a minimum threshold.