A sound attenuating heat exchanger for an internal combustion engine includes a housing, a barrier wall and a fin. The housing includes an exhaust inlet, an exhaust outlet, a coolant inlet and a coolant outlet. The exhaust inlet is connected to the exhaust outlet by an exhaust flow passage. The coolant inlet is connected to the coolant outlet by a coolant flow passage. The barrier wall fluidly separates the exhaust flow passage from the coolant flow passage. The fin extends from the barrier wall into the exhaust flow passage, and includes a resonator adapted to attenuate sound waves traveling through exhaust gas within the exhaust flow passage. The barrier wall and the fins are adapted to exchange heat energy between the exhaust gas flowing through the exhaust flow passage and coolant flowing through the coolant flow passage.