Adding Sound to a Motive Power Diesel?

[Davevide]

I want to add soud to my DCC onboard HO scale F7 Diesel.  The DCC board is very different from other engines I've worked with.  Can anyone suggest a sound decoder and give me some installation tips?  Thanks. 

[ABC]

The F7 is not easy to install sound in due to a lack of space for a good quality (large) speaker and baffle.

[Davevide]

I am aware of the size limitations.  LokSound might have some speakers that would work.  If anyone has performed a sound modification with a F7Diesel with existing DCC Onboard, I would like to hear from you.  Thanks