Sound, Motor & Function Decoders

My son & I have PROTO 1000 Diesel EMD F3A-B Sets. The powered locos are equipped with an eight-pin plug for easy decoder installation. Our problem is that we've been looking through books & have no idea what sound card & speakers we are going to need that corresponds with these type of locomotives. I was told that they would need sound cards that are from the "Early Diesel" era. If this is true, please tell me what sound cards,speakers & wires do we need to make this happen? We are fond of F-units, and the Proto 1000 F-units are ...