If the irritation seems to be brash or brassy, I agree with the 1.5k to 1.6k give or take 500 Hz. assessment. If the irritation is more shrill, I find more often than not that the offending frequency is around 3.1k. It could also be both regions.
You may want to start with a larger reduction like 6 db or greater just because it is easier to hear bigger changes and then add them back in as needed after you find the offending frequencies.