The aspect ratio 4:3 was used for 35 mm films in the silent era. It is also very close to the 1.375:1 Academy ratio, defined by the Academy of Motion Picture Arts and Sciences as a standard after the advent of optical sound-on-film.
During the early days of cinema, the 4:3 format was widely used for 35 mm films. This aspect ratio is remarkably similar to the 1.375:1 Academy ratio, which became the industry standard following the advent of optical sound recording.