What would be the equivalent of "spam" if referring to face-to-face conversation?

If unsolicited bulk mail in your inbox is referred to as spam, what would be its equivalent for someone talking indiscriminately, but face-to-face without the intervention of technology.

Yack, Yack, Yack or Yacking

Yack -- Merriam Webster "to talk in a loud way often for a long time"

"Even though I was obviously trying to do the crossword, my seat-mate kept up a constant yack, yack, yack during the entire flight."

"Show the tiniest response, and she will go on yacking forever."

How about "loquaciousness?"

loquacious adj.

talking or tending to talk much or freely; talkative

(noun: loquaciousness)

Source: Dictionary.com

If you need something strong:

verbal diarrhea