also pitter-pat, 1520s; imitative. As a noun from 1580s.
Rain was falling, pit-a-pat, and he was without cover on a wet patch of grass.
Do you hear that, then—that pit-a-pat, like sheep going by on the street?
He had prepared them pit-a-pat the night before, and gone over them with Thoms in the morning.
There it was again, pit-a-pat, pit-a-pat, very soft and coming nearer.
His heart palpitates, and, with a pit-a-pat motion, comes mounting up to his mouth.
Tink hears her voice—and hearing that, Trots nearer with a pit-a-pat!
He held his breath and listened, while his heart went pit-a-pat, pit-a-pat.
At last one day, when Dash had lost all hope, he heard the pit-a-pat of four small feet in the yard.
Its feet went pit-a-pat, pit-a-pat, with a horrible clanking noise like chains.
My hand trembles, and my heart goes "pit-a-pat" as I think of being present at the trial.