Theater-quality sound draws the viewer into the action. Advancements in movie sound systems make the audio in a movie seem real. Smashing glass as cars crash, the jarring boom of an explosion, or even a musical accompaniment during a touching scene sets the mood. There are five sound systems used to transfer the sounds from the movie to the audience. Understanding how they work helps viewers choose the right movie sound system or simply become informed about the technology.
Analog Sound Systems
When someone talks or something makes a noise, those sounds are really just a series of vibrations traveling through the air. Analog recordings capture those vibrations with a microphone and convert them to an electrical signal. That signal is transferred onto a vinyl surface, such as a film or tape reel or the surface of an LP record. When played back, the stylus or tape deck head follows the movement, replicating the vibrations to create the sound for the listener.
Analog does pick up ambient noises and is sensitive to dust and particles on the vinyl surface, which is why there is often a low-pitched hiss or clicks and pops.
Thomas Edison, inventor of the phonograph, first recorded sound in 1877. That simple invention opened the doors to audio recording. In 1926, Warner Bros. became the first movie studio to release a movie, Don Juan , with a music soundtrack and the sounds of swords clashing. The Jazz Singer, released in 1927, was the first movie with actual dialogue.
Digital Sound Systems
Over time, analog formats wear out from repeated use. To prevent the loss of sound quality, digital formats became popular. With digital sound, the audio is converted to binary code for a computer to read. Each of those numbers, known as a BIT, tells the computer what noise to make. There is still some ambient noise, but the computer editing software can polish it to create flawless recordings.
In the 1980s, after CDs came out, there was a new form of audio available to production companies. Kodak and Optical Radiation Corporation came out with Cinema Digital Sound in 1990 with their movie Dick Tracy . With digital sound quality, the movie soundtrack no longer had the pops or hisses that analog recordings were known for. This made it easier for viewers to hear the actors without distracting noises.
Digital Theater Systems (DTS)
Digital Theater Systems (DTS) launched in 1990. Universal Studios and Steven Spielberg worked with a scientist to come up with digital sound that ran on multiple channels at one time.
The number of channels depended on the surround sound format. For instance, 5.1, their original format, had five for normal sounds and one for low frequencies, such as deep bass tones. There was also 6.1, established in 2000, that added one channel for normal sounds.
The first movie to use DTS was Jurassic Park . The audio CD was separate and required a CD player and movie projector in the projection room. DTS sound eventually became a key component in video games, the Sony PlayStation 2 was the first video game system to use DTS. It also expanded into the cars people drove when, in 2004, Nissan added DTS to their Acura.
Dolby Labs started in the 1960s. They were the first company to work to reduce the background noise in analog recordings. They came out with Dolby Surround in 1982. They also developed a digital coding system in 1984 known as AC-1, but AC-3, aka Dolby Digital, wouldn’t be invented until 1991.
Dolby Digital 5.1 digital audio is used in movie theaters, homes, and Internet websites. The technology is available on audio music, Blu-ray (high-definition DVDs), and DVDs. The 5.1 format has speakers in the front, left, and right to showcase. Two additional channels put viewers in the center of the action with sound effects coming from extra speakers on the left and right.
Dolby Digital movies and audio are combined on one track. The soundtrack to the movie is embedded on the edge of the film reel. Unlike DTS, movie theaters only need one piece of equipment to play Dolby Digital movies. This makes it easier for the projectionist in the booth.
Sony Dynamic Digital Sound (SDDS)
Sony Dynamic Digital Sound (SDDS) takes theater sound to a new level. To bring viewers into the action with 1993’s Arnold Schwarzenegger blockbuster, Last Action Hero , an 8.1 digital sound system was created. With eight channels, the layers of sound are incredible. In the movie’s projection room, an SDDS reader is attached to the film projector. As the film reel run, the reader picks up the sounds and sends them to a decoder that translates the computer code into dialogue, music, and sound effects.
Speakers are set up throughout the movie theater. There is one in the center, two each on the left and right, and one subwoofer speaker near the screen. The right and left walls have an additional row of speakers, and the back wall has left and right speaker sets. Sound comes at the viewer from all angles.
Sound Quality is a Personal Preference
Movie enthusiasts all have their preference when it comes to movie audio. Some prefer the dimension that comes with analog, but others prefer the long-lasting quality of digital sound. What’s important is to pick the equipment that suits a user’s price range and tastes.