Seeburg DDS-1 speakers.
DDS for Discotheque Dance Speaker.
They were introduced in about 1964 or 1965 for use with Seeburg's Discotheque jukeboxes.
Seeburg marketing came up with entire Disco packages for dance spots, including jukeboxes, speakers, wall banners, advertising material, coasters, and pre-fab dancefloors.
-kevin