What is Surround Sound?
Surround sound is aptly named for surrounding the listener with an acoustic environment that goes beyond the two-channel stereo experience of yesteryear. Today’s home theater systems place the viewer or listener inside a virtual landscape of sound.
In real life, we experience sound in the context of ambient noises. If someone is talking to us, we might also hear the faint drone of a jet far above, a schoolyard full of children nearby, birds in the trees, and a television blaring from the next room. These sounds are spread throughout the audible landscape. Surround sound faithfully recreates an entire landscape by sending the right sounds to the right places to simulate an experience closer to real life.
The first incarnation of surround sound was surround sound 5-1, which included five speakers and one subwoofer for delivering bass sounds. This is also referred to as Dolby Digital and Digital Theater Systems (DTS) sound.
Next came DTS Extended Sound (DTS-ES) or THX as surround sound 6-1. This surround sound system uses six speakers plus a subwoofer. The sixth speaker takes the position of center rear to create a more complete three-dimensional soundscape. Surround sound 7-1 adds yet another speaker to the mix. It takes the rear center channel and divides it in two, flanking speaker positions for an encircled rear.
While a stereo recording will play through a surround sound system, the receiver will simply send the left channel to half of the speakers and the right channel to the other half. To get the full effect of surround sound, the original recording must be encoded for it. When this is the case, the receiver in the home theater system is able to send specific sounds to specific speakers, creating “placed sounds” to build an acoustic atmosphere.
For example, imagine watching a movie in which the main character is standing on the sidewalk when he hears his friend call his name just behind him. He turns to his left and sees his friend. Watching this movie in surround sound, the friend’s voice will come from the rear left speaker, placing you inside the sound track.
The greater number of speakers a surround system has, the greater its ability to place sounds where they belong. The difference becomes clear when, for example, watching a war scene with munitions exploding all around. Surround sound will have you ducking bullets whistling by and jumping at bombs exploding behind your back. Compare this to the entire sound track playing through two front speakers in a stereo system. Surround sound adds authenticity because it puts you inside the action of the picture, or in the case of music, on stage with the band encircling you.
Surround sound systems have minimum requirements for amperage generated by the receiver. If the receiver is not powerful enough, it won’t be able to push the sounds through the speakers with sufficient gusto. If the receiver has far more power than the speakers require, it will be very easy to blow the speakers out by accidentally leaving the volume up when powering up the system. Also, be sure that the receiver supports the type of surround sound desired. A receiver that only supports 5-1 surround sound will not be able to support 6-1 or 7-1 speaker systems.
Written by R. Kayne
