Variations depending on tone:
The success of paved the way for the digital formats used today. The "Stereo" branding eventually evolved into Dolby Digital and the modern gold standard, Dolby Atmos . Key Feature Dolby Stereo 1975–1990s 4-channel matrixed sound (L, C, R, Surround) Dolby Digital 1992–Present
There is nothing quite like the distinct, warm audio of . Before the era of digital surround, this was the industry standard that revolutionized how we heard movies.
Before the mid-1970s, most films used a single "mono" audio track. changed this by using a 4-channel matrix—Left, Center, Right, and Surround—encoded onto two optical tracks on standard 35mm film.