Adding sound to N&W J class

[bobv]

I have a very nice running Bachmann Spectrum Norfolk & Western J class #611 with DCC on board
Question: If I wanted to add sound- how complicated is it to add?  I see a spot in the tender with holes for the speaker.
Do I have to replace the current circuit board or is it just a plug in a component?
Thanks

[pdlethbridge]

It should be just plug and play. heck with sound traxx for the proper decoder and speaker for that engine