Thanks for the quick response! Definitely helpful links! Basically, my idea is pretty simple: I just want to add 3 new sound FX when hull reaches 75%, 50%, and 25%, just to alert me to my damage as it is not entirely apparent right away in the heat of a firefight. Having 3 new sounds going off would be a great audio cue for me as to my current ship status.
That should be very easy to implement. Basically, you could do it as an $On Frame hook, which runs every frame, keeps track of the player's ship's hull integrity in some variable, compares the current integrity to what it was last frame, and plays the appropriate sound if it's dropped below the given threshold.
You should find plenty of examples of $On Frame hooks which do things based on the player ship's attributes. The Velocity Indicator in the examples page would be one. Usually the trickiest part ends up being making sure that a script doesn't barf any error messages when the player is dying, at mission start, restart, quick restart on death, and that sort of situations when the player ship handle can be in unexpected states.