An onomatopoeic sound for a short, sharp ping; also used in manga or colloquial speech to indicate a sudden idea or a notification ding.
スマホの通知音がピーンと鳴って、新しいメールが届いた。
The phone gave a 'ping' and a new email arrived.
問題を見て、彼の頭にピコーンと答えが浮かんだ。
He looked at the problem and a solution popped into his head with a 'pikon' sound.
ゴムがはじかれてピューンと音がした。
The rubber snapped and made a 'pyoong' sound.