Orthophonic sound is not some alternative to monophonic, duophonic, stereophonic and quadraphonic sound. Orthophonic means that the recording was designed for playback on a light tracking (relatively speaking) and with electric not acoustic amplification. In short, Orthophonic is the brand RCA used. Electrical recording was developed at Western Electric. It was the manufacturing arm of big Ma' bell. This was a really productive engineering group. They produced the Vitaphone system, Westrex optical sound, single-groove stereophonic sound, indestructible home phones, productivity studies, and half-a century of other innovations.Western Electric saw the same problem in acoustic reproduction that everyone else did. The signal to noise ratio sucked. The signal was low and the noise was high. The noise came in two forms, inferior recording technology, and playback based on energy produced by friction. Western Electric solved this at each end of the equation. they and other companies were improving recording technology. Electrical recording was a series of steps, but playback was all them. There are some great phonograph manual scans here. Of course they were met with resistance when they showed it off to the record companies. Much like stereo did in the 1960s, thsi change threatened to make their entire existing catalogs obsolete. But the rapidly improving quality of radio gave them competition in terms of fidelity. this was not an innovation they could afford to shelve. Both Victor and Columbia experimenting with electrical recordings in 1924. Radio had raised the bar even at this early stage, and the two media platforms saw each other as competition.
In the 1950s, RCA Victor re-used the brand to introduce new innovations in LP fidelity with the name "New Orthophonic." It's about as original as "New England" and "New York." But it worked. RCA saw the brad as one that succeeded, one that kept them alive through the golden age of radio.