Br204 Sound Logic Bug, It Dose Not Change The Engine's Tune Based On Current Gear Position

One of the best things about this BR204 is listening to the engine because its all diesel and noisy and what not. So one of the common things it dose is that it changes it's tune according to what gear you set it to, that's what a engine that runs on diesel or gasoline dose. Here in TSW this isn't functioning. When you approach the locomotive you can hear the engine calmly humming away but only when you sit down it changes it's tune, why? it has no reason to. The tune of the engine then remains the same regardless of the gears position, i.e forward, reverse, engine only or neutral. Each of these positions has it's own tune. Would really suggest this is looked into very much.