different between pinging vs knocking

English

pinging

pinging (plural pingings)

The sound of a ping.
- 1870, Sir John William Kaye, A History of the Sepoy War in India, 1857-1858 (volume 2, page 320)
  […] walking across the open in stern composure, with the pingings of the hostile bullets, and the imploring cries of his comrades to save himself, sounding in his ears.
- 2011, Ramona DeFelice Long, Fish Tales: The Guppy Anthology (page 202)
  When she entered, her eyes and ears were assaulted by neon lights in bright colors, the hypnotic, musical pingings of electronic slot and poker machines, and the clinking of coins dropping into payout trays.
The act of sending a ping, as by a submarine or over a computer network.

knocking

knocking (plural knockings)

Send