I would venture a guess that it is probably a script telling that sound to play, so do the following:
Backup a copy of the mod plugin in a safe folder before starting.
Open the mod plugin (regular one from Data folder) at Xedit and expand its scripts tab.
You can try to delete all the scripts at once, save, exit, and test in-game. If the sound is gone you know it was an script, so now you gotta pinpoint which one. Restore the plugin to original from your backed up copy, and do the same process at Xedit but deleting only HALF of the scripts this time, save, test in game.
Keep deleting scripts, testing in-game, and restoring the plugin to original, until you find the exact script that makes the thing happen. When you do, take note of the script name, restore the plugin to original once more, and open the plugin as the "active" file in NV GECK.
Find the script by its name, look the contents and try to figure out how to remove the sound, if that is what you want to do. If the script compiles successfully after your change, save the mod plugin and test in-game.
Try this process and see how it goes, I can give some further info/help if you need.
BTW, you can probably use this procedure to troubleshoot most mods, so long you know their base structure and working process (since not everything is script related, and some stuff needs a clean save to test).