All About Surround Sound

All About Surround Sound

by Dave Donovan

There’s nothing like sitting in your easy chair, watching your favorite movie totally encompassed by the sound. So much time and effort is placed on the soundtracks for today’s movies that it’s almost a crime not to hear them as they were intended. For most movies, that means bullets coming from the left, monsters breathing down your neck or a spaceship flying overhead.

Without a doubt, the best way to experience a movie outside of the theater is through a quality digital surround sound system in your living room. And since the invention of DVDs, the movies have never looked or sounded better. While the soundtracks on all DVDs are considered “digital,” not all digital audio is the same.

For example, a DVD of “Funny Farm,” the 1988 movie starring Chevy Chase, features a regular surround sound soundtrack. Newer DVD releases, like “Spiderman 3” are normally released with at least digital 5.1 surround sound. Meanwhile, you may notice other DVDs to have additional audio options, like DTS or DTS-ES. What does all this mean? Let’s get it clarified.

When you look on the back of a DVD case, you can usually find the audio options in the lower left corner, as well as a picture icon of the speaker configuration. Here are a few of the more common audio options.

Digital Stereo – This configuration shows only two speakers, as that is all that is used for the soundtrack. The left and right speakers are the only ones which will have the audio playing. If your receiver has a “virtual surround” option, then you can imitate a surround sound track through this option using the receiver.

Surround Sound – The diagram will have three small squares on the top of the larger square and one in the center of the bottom part of the square. This means that the dialogue will come through the center speaker, the left and right audio channels will be separated with the front two speakers, and the rear speakers will get a single, identical audio feed, without left/right dispersion.

Digital 5.1 Sound – This diagram will show the same three front speakers plus two independent rear speakers. With this audio option, each of the five main speakers (center, left front, right front, left rear and right rear) get independent audio signals. The .1 (of the 5.1 signal) is the individual audio feed to the subwoofer, which handles the low frequencies in the soundtrack. The subwoofer signal is called LFE (low frequency effect). With this audio option, if a helicopter flies in a circular motion on the video, the audio will follow the action.

Digital 6.1 and 7.1 Sound – These audio options are similar to digital 5.1 but with an additional middle rear (6.1) or side (7.1) speakers. Often, these audio formats will be labeled as DTS-ES. These audio options are only compatible with a receiver capable of decoding the audio signals. A receiver pumping out 7.1 digital audio totally encompasses the viewer with audio from the front, the sides and from behind.

DTS – Similar to digital 5.1 audio, DTS stands for Digital Theater System. Audiophiles understand that DTS is superior to 5.1 because it is encoded at the highest legal bitrate of 1,500 kbit/s whereas digital 5.1 (or AC-3) is encoded at 640 kbit/s. However, in blind tests, it is virtually impossible to tell the difference. Even so, you won’t find one person who has a DTS receiver not using the audio format if the DVD offers the option.

THX – THX is a certification for quality assurance, not an audio option. While a DVD may have the THX logo on it, all it means is that the soundtrack for the film is THX certified to sound as near to the intentions of the mixing engineer as possible. THX was created by Lucasfilms for the theatrical release of “Return of the Jedi.” It stands for Tomlinson Holman’s eXperiment after the name of the technician who developed it.

With the continuing development of DVDs including HD-DVD and Blu-Ray discs, audio options continue to grow as well. HD-DVDs and Blu-Ray discs alike feature mind-blowing audio clarity with DTS-HD High Resolution Audio. Regardless of what type of audio you feel is superior, one thing we can all expect is that video and audio technology is constantly improving. Before we know it, we may really end up in the middle of the action!

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