I use a thumb pick for guitar and as much as anything, it gives me a clue to keep the wandering voice in tune. On the occasional unaccompanied song, I usually begin "in ear" as it were and my hand drifts upwards occasionally to see if I still am....

That said, just like sandals with socks, beards and asking if this beer is real ale, sticking your finger in your ear is living the dream........