It also says that Karaoke in Japan is predated by sing-a-long programs in the US. https://en.wikipedia.org/wiki/Karaoke?wprov=sfti1

Besides that I assume any patent from the 70s is now expired.

"The world's first karaoke machine, the Juke-8, was built by Japanese inventor and musician Daisuke Inoue in 1971. But it is Filipino inventor Roberto del Rosario who holds the machine's patent. He developed the Karaoke Sing-Along System in 1975."