Editing Stereophonic sound (section)

===Lateral and vertical recording===
[[Thomas Edison]] had been recording in a hill-and-dale (vertically modulated) format on his cylinders and discs since 1877, and [[Berliner Gramophone|Berliner]] had been recording in a side-to-side (lateral) format since shortly thereafter. Each format developed on its own trajectory until the late 1920s when electric recording on disc, utilizing a microphone, surpassed acoustic recording which required a loud performance into what amounted to a megaphone in reverse.

At that time, [[AM radio]] had been around for roughly a decade, and broadcasters were looking for better materials from which to make phonograph records as well as a better format in which to record them to play over the narrow and thus inherently noisy radio channel. As radio had been playing the same shellac discs available to the public, it was found that, even though the playback system was now electric rather than acoustic, the [[surface noise]] on the disc would mask the music after just a few plays.

The development of acetate, bakelite, and vinyl, and the production of radio broadcast transcriptions helped to solve this. Once these considerably quieter compounds were developed, it was discovered that the rubber-idler-wheel-driven turntables of the period had a great deal of low-frequency rumble{{snd}} but only in the lateral plane. So, even though with all other factors being equal, the vertical plane of recording on disc had the higher fidelity, it was decided to record vertically to produce higher-fidelity recordings on these new materials, for two reasons, the increase in fidelity by avoiding the lateral rumble and to create incompatibility with home phonographs which, with their lateral-only playback systems, would only produce silence from a vertically modulated disc.

After {{frac|33|1|3}} RPM recording had been perfected for the movies in 1927, the speed of radio program transcriptions was reduced to match, once again to inhibit playback of the discs on normal home consumer equipment. Even though the stylus size remained the same as consumer records at either {{convert|3|mil|μm}} or {{convert|2.7|mil|μm}}, the disc size was increased from {{convert|12|inch|cm}}  to the same {{convert|16|inch|cm}} as those used in early talking pictures in order to create further incompatibility. Now, not only could the records not be played on home equipment due to incompatible recording format and speed, they would not even fit on the player, which suited the copyright holders.