Would this also work with a loud whistler right behind me?
For that, you want to use Hard Limiter. Highlight the whistling section only, and then Effect > Hard Limiter. What I've found works well for this is setting the Residue Level to 0.7, and then experiment with the limiting level. Try -12, then undo/redo until it's limiting the offending noise to around the level of the music but not so much that you're reducing the level of the music itself.
BTW, the Residue Level setting is to avoid simply chopping/clipping the waveform, which is what you'd get if left at default. There's more details in the online manual if you're curious.