I like Tsunami sound decoders after having tried MRC total junk don't even think about using them. QSI has a good reputation as well as Loksound. Check the manufactures websites most of them have application data for specific locomotives if not just email them with what sound decodert fits your engine.
Some times it easier to swap out the entire decoder then it is to just add an additional sound decoder at least for me it is. If you have a DCC equipped locomotive then you have an 8 or 9 pin NMRA plug connected to the decoder so installing a new sound decoder should be relatively easy. it's just mounting the speaker can some times be a little difficult.
I am new to the model railroad hobby and I have purchased my first locomotive, a Bachmann DSH840CW, model #83502 that does not have a sound decoder installed.
I am looking for a recommendation for a sound decoder that would work with the factory installed DCC decoder. My control center is the Bachman EZ Command Dynamis Controller, model #36505.
Any help would be appreciated.