Slate wants to know why American auctioneers use that odd machine-gun cadence:

They talk like that to hypnotize the bidders. Auctioneers don’t just talk fast—they chant in a rhythmic monotone so as to lull onlookers into a conditioned pattern of call and response, as if they were playing a game of “Simon says.” The speed is also intended to give the buyers a sense of urgency: Bid now or lose out. […] The auctioneer’s cadence must be learned and practiced. Start by chanting pairs of numbers in ascending order (1, 1, 2, 2, 3, 3, etc.), then do them backward. When you can work in conversational banter without breaking your rhythm or losing track of the count, you’ve got it down. Take brief, shallow breaths at regular periods in between the bid calls. Avoid difficult sounds that strain your throat, like K or a hard G. The pros keep their vocal chords loose by chanting in the shower or in the car on the way to a show. Tongue-twisters are a great way to stay in shape. […] A professional must also learn how to squeeze out every last dollar from a sale. If two people are bidding each other up, for example, a good auctioneer will start talking directly to them, cocking his head back and forth and gesturing to them as he urges them on. The sense of competition is thought to move people past their predetermined price limits.

Why Do Auctioneers Talk Like That? (Slate)