Sheppard, who is believed to be in his late 90s but refuses to divulge his exact age, has a bronchial infection that will force him to snap a string of 121 consecutive postseason games announced at Yankee Stadium, dating back to 1951.
Sheppard had also missed the final seven games of the regular season while longtime backup Jim Hall, who closely resembles Sheppard's concise and correct style, filled in.
"Doctors are monitoring my progress," Sheppard said in a statement. "And I am hoping to get back to Yankee Stadium to watch -- and announce -- Yankees playoff games long into October."
Sheppard is in his 57th season as public address announcer at Yankee Stadium. His postseason streak began on Oct. 4, 1951, in Game 1 of the World Series vs. the New York Giants. The lineups that day included Joe DiMaggio, Phil Rizzuto, Yogi Berra and rookies Mickey Mantle and Willie Mays.
"I'll miss him," said Reggie Jackson, a Yankees special advisor who famously dubbed Sheppard, "The Voice of God."
"There is a guy [Hall] who sounds very close to him, and it doesn't come to you immediately if you're just listening. But the old guard will miss him greatly. He's a great person, a great part of our history, and a great part of my life -- he helped me write my Monument Park speech and my Hall of Fame induction speech."
With that, Jackson paused, smiled, and looked skyward.
"Much ... too ... wordy," Jackson said, drawing Sheppard's tone and cadence.
Sheppard's first game as Yankees public address announcer was on Opening Day, April 17, 1951, as the Yankees defeated the Red Sox, 5-0.
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.