If you were there and you were old enough, you remember.
It took me this long to realize that WABC would broadcast using a heavy audio delay/echo.
What you're hearing (it sounds like the speaker is at the the bottom of an empty trash can) isn't an effect that was added for this upload.
It was, instead, a gimmick that WABC used so you would know you found the right spot on a crowded AM radio dial. WABC was also a "boomer" station and you could easily tune it in if you lived near Scranton/Wilkes Barre at night up in the Pocono's of Penna.
Unwrap some Hostess Twinkies and open a warm bottle of Yoo-hoo. This is the NYC experience.