Fluke T100 LED for Single Pole Phase Test Query

[markrutter]

Apologies if this seems silly but can anyone enlighten me as to the meaning of this function? Does it simply light and buzz when one of the cables you are testing has a link to >100v (even though the circuit being tested is dead)? I find this buzzing when I'm attempting to establish continuity even when I'm not (knowingly) pressing the associated electrode on the body of the tester.

Any advice would be appreciated as I'm sure this function would be useful if I only knew what it was.