Barker

wiktionary

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From Middle English berkere; equivalent to bark(“dog noise”) +‎ -er.

From Middle English barker; equivalent to bark(“surface of tree”) +‎ -er.

etymonline

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barker (n.)

late 14c., "a dog;" late 15c., "noisy fellow;" agent noun from bark (v.). Specific sense of "loud assistant in an auction, store, or show" is from 1690s.