A closed-circuit television performance of Carmen from the Metropolitan Opera House in New York City to thirty-one theaters across the United States on December 11, 1952 included a stereophonic sound system developed by RCA.[9] The 1958-1959 season of The Plymouth Show (i.e., The Lawrence Welk Show) on the ABC network was broadcast with stereophonic sound in some cities, with one audio channel broadcast via television and the other over the ABC radio network.[10] By the same method, NBC television and the NBC radio network offered stereo sound for The George Gobel Show on October 21, 1958. ABC's Walt Disney Presents made a stereo broadcast of The Peter Tchaikovsky Story, including scenes from Disney's latest animated feature Sleeping Beauty, on January 30, 1959 by using ABC-affiliated AM and FM stations for the left and right audio channels.
Regular network transmission of stereo audio began on NBC in 1984.
https://en.wikipedia.org/wiki/Stereo