Lacking a microphone, Jewett practiced announcing on the radio by using a tin can tied to a stick. He joined the announcing staff at NBC in 1930 after passing their microphone exam. The exam required him to speak a tongue-twister without stammering or whistling: "The seething sea ceaseth and thus the seething sea sufficeth us." He also had to demonstrate fluency in a foreign language. (Jewett was fluent in Japanese from his childhood years.)
