The next time you watch an old movie, close your eyes for a few minutes and just listen. Without the visuals, the movie will likely feel flat—and you may even have a hard time understanding the dialogue.

Film soundtracks from the 1960s were “little more than audible subtitles,” Ioan Allen, Senior Vice President at Dolby Laboratories, said recently, and most moviegoers at the time didn’t realize how poor the sound quality was: “It’s in color. You can see the lips move. And the brain will do all kinds of compensation to understand the words.”

Ioan AllenAllen, who was hired in 1969 to work with the music industry, was instrumental in the company’s innovations in cinema sound beginning in 1971. He recently spoke with a group of Dolby employees about the history of the company’s film program. Playing movie clips from 1934 to the present, Allen took his audience from the introduction of Dolby Stereo®, which expanded movie sound from mono to three speakers (left, center, and right) behind the screen, to Dolby Atmos®, which lets the filmmaker precisely place sounds all around the theatre.

(For a visual look at the development of movie sound, check out our cinema sound history infographic.)

Into the world of cinema sound

Dolby Model 360 A-type noise reduction unit

Dolby Model 360 A-type noise reduction unit. Dolby noise reduction dramatically reduced the amount of hiss in multitrack recording for music and film.

By the end of 1971, Dolby® noise reduction equipment dominated the music recording industry, and the company needed another challenge to conquer.

Film was clearly the next frontier. Where music recordings included only a few tracks of sound, movies contained hundreds dialogue, music, and sound effects. “The more tracks, the more hiss,” Allen noted.

“We did a bunch of mono films with Dolby noise reduction,” said Allen, “but to be successful, we had to introduce stereo.” Stereo would produce a richer sound and attract more moviegoers. Working with Eastman Kodak, Dolby engineers developed Dolby Stereo in 1974.

The technology’s commercial breakthrough was Star Wars (1977). “Every print of Star Wars was a Dolby Stereo print,” he said, and audiences came to screenings in droves.

Successful movies of that time ran for six or even nine months, Allen pointed out. With ticket sales booming, a cinema owner who bought new equipment to run Star Wars in Dolby Stereo could recoup the cost in one week. In San Francisco, the 1,350-seat Coronet theatre was one of about 40 in the United States that began showing a 70 mm Dolby Stereo magnetic print of the movie in late May 1977. By early November, the Coronet had sold more than $2 million in tickets.

1977_StarWarsEp.IV_-300More hit movies in Dolby Stereo followed, including Close Encounters of the Third Kind (1977) and Superman (1978). For Allen, another breakthrough was Terence Malick’s Days of Heaven (1978), which he characterized as “the first quiet, subtle movie” to show the power of Dolby Stereo.

“By 1985, every film—without exception—was a Dolby Stereo movie,” said Allen.

Analog sound gives way to digital sound

By 1986, the music industry wanted more noise reduction. Company founder Ray Dolby spent much of his time developing Dolby spectral recording, known as Dolby SR, which provided 25 decibels of noise reduction and extremely low distortion. “I would not hesitate to say that [Dolby] SR is still probably the best recording quality you can get,” Allen noted.

Dolby SR was used in analog music recording and became ubiquitous in films, starting with Robocop and Inner Space in 1986. But by 1992, Allen said, “the world was digital crazy.”

Working with digital audio compression technologies to “squash more things into a smaller pipe,” Dolby engineers in 1992 developed Dolby Digital, which delivered 5.1 channels of cinema sound: left, center, right, left surround, right surround, and subwoofer (that’s the “.1”). Digital audio data on 35 mm film is stored just left of the analog soundtrack, between the sprocket holes, where film receives the least wear over time.

Analog-digital-tracks-on-filmAsked for a rear surround channel on 35 mm film, Dolby engineers created Dolby Surround EX™, which encodes three surround channels into two surround tracks. And with the introduction of digital cinema, Dolby Surround 7.1 split the rear surround speakers into left and right channels.

Dolby Atmos

It’s conceivable that companies could “carry on piling up channels,” as Allen put it, and some have. But there’s a drawback. “If you have a pan of sound going from the screen to a side wall, that texture change, that transition from a single lefthand front loudspeaker to the lefthand [speaker] array will never sound smooth. The texture will always change.”

That led Dolby engineers to develop Dolby Atmos. The new format gives filmmakers the flexibility to place a sound anywhere in the theatre, even overhead, then precisely move that sound to reflect the action on the screen. The effect is to transport you into the story in a way no other cinema sound can.

Filmmakers have praised the new audio format. Academy Award® winning director Alfonso Cuarón used Dolby Atmos in Gravity, which won seven Oscars, including the awards for sound editing and sound mixing. Cuarón said, “I was always asking for possibilities in the mixing room that were not achievable, and now finally with this system—that is, Dolby Atmos—you know, [it’s] this dream come true … You really can explore the possibilities of depth and separation as never before.”

More than 100 film titles have been released in Dolby Atmos. At last count, more than 450 Dolby Atmos equipped screens have been installed worldwide, with another 150 planned.

Although proud of what’s been done so far, Allen, who won an Oscar® in 1989 for his many technological contributions to the film industry, will consider the format a true success when filmmakers begin using Dolby Atmos to make movies that plumb its subtle power: “I’d like to find the Days of Heaven of this day and age in order to show how Dolby Atmos can be used for a quiet movie.”

Enter your email address. We'll notify you about new Dolby Lab Notes posts.