So don't be disheartened anymore bro i have be watching ur entire progress while u made the unit and for that +rep.
Now i suppose better than rep u need to see the solution.
So here it is. I presume u already have the vanilla snd files if not download them here.
Step 1-Then place them(39 snd files) in the data folder of your mod.
Step 2-Open the descr_sounds_units_fire.txt file and look for this entry highlighted in red.
Step 3-The entry should be like this:-
Don't think just change it by deleting the one blue
Now save changes to the file.
Step4-To make the snd changes into effect all you have to do now is delete the events.dat & events.idx files from sounds folder of your mod and launch your mod so that they would be re-generated all over again saving all the changes you have done.
After that u can remove the files from ur mod and keep some where safe if u ever get the craving to change something related to sounds.
SO did you get it right of course u did.