Slot machine payout sounds come from physical casino machines, where bells, chimes and the clatter of coins into a metal tray were designed to celebrate a win and draw attention from other players nearby. As machines went electronic, those coin noises were sampled and kept because players associated them with winning. The medium payout version became a staple stock effect for games, adverts and videos, used whenever a moderate prize, bonus or cash reward needs to sound exciting but not like a life-changing jackpot.