Similarities and differences between surround sound and stereo

[sionelliott]

Hi, I have an important interview for a university next week and one of the questions is...

"What are the similarities and differences between surround sound and stereo?"
Any Help is appreciated.

*** BTW - this is in regard to music technology ***

Thanks!!!!!

 

[markw]

Similarities are that both have a front right and left speakers.

Differences are that surround sound generally adds a center and at least two surround speakers.

 

[gmichael]

Surround sound also includes a subwoofer for the bass. Stereo can include a sub, but it often does not.
Having a good sub let's you cut the low frequencies from going to your main speakers. These frequencies are generally the hardest to reproduce and require a lot of power from your amp. With the sub handling these, your receiver/amp does not have to work as hard. This gives you more headroom.
Also, surround sound is more than just having extra speakers around the room. Each speaker is getting it's own discrete signal. So you can hear one instrument coming from in front of you while others may be behind you. The effect of which makes you feel like you are in the band instead of just watching them. This is especially useful while watching movies. You can see a jet fly past you and also hear it move from one side of the room to the other. Bullets shot at you can be heard hitting the wall behind you. If watching a ghost story you could hear a door creek open from behind you.
Explosions can be felt as well as heard with powerful sub. It makes the movie come alive.

The drawback for surround sound is that most music is recorded in 2 channel stereo. Although there are techniques to convert 2 channel to surround sound, it is not the same as playing something back in the same form as it was recorded in. There is always a little something lost.

 

[son-yah-tive]

In Stereo, there are no sound effects. In Surround Sound you have a variety of sounds. Concert Hall, Jazz Club, Stadium and many other settings that mimmic real venues that stereo can't reproduce.

 

[TLS Guy]

Actually for most things not much.

A good stereo two channel system can be accurate or not. But good accurate ones, have excellent fidelity balance and front to back perspective. The perspective is important and something few speaker systems of any stripe posses.

Whether the sub is external or not, is not an overriding issue. The last octave should be a luxury to a good system in any event. All things being equal I personally prefer a good system with integrated full range speakers rather than the sub approach. The bass frequencies are not the hardest to reproduce. It is the mid range that is most critical and the frequency range that to a large extent determines whether a speaker system is any good, and most are severely wanting. The problem with the last octave, is that speakers really do need to be large. Small subs lead to inevitable compromise, especially in terms of efficiency and requirement for brute force amp power. Large enclosures properly designed need actually very little power to reproduce the last octave.

At the current time we are like the first 10 to 20 years of stereo, where there were good speakers, and one good speaker ended up getting exchanged for two poor ones. Now we have gone to if not exchanging two good ones for five to eight poor ones, then are least adding three or five poorer ones as often as not.

The object, at least for music, is to provide a sense of the whole space to the reproduction and provide accurate antiphonal effects when required. This occurs to a varying extent depending on the skill of the recording engineer. Surround microphone techniques are still very much in evolution, but I would say improving over time.

Movies are a slightly different issue as there are more moving targets in different directions. However my sense is that compared to some of my SACDs, I think the power put to the surrounds is limited as the balance engineers assume correctly that the surround channels are sub par. I have some SACDs that demand as much from the rear speakers as the fronts.

I think for best surround results, the room needs to be purpose built and not a general use room and the speakers all need to be accurate and capable of similar spl. Most non purpose domestic rooms would probably be better off with good stereo rather than surround systems and that includes for movies. There are an awful lot of domestic spaces where surround is far less than an ideal solution in my view.

Two channel systems can be very good indeed, and really most people would be better off putting a good two channel system together and then adding high quality surrounds as funds and the suitability of the space permit. But that just is not sound sexy, or what ever you want to call it.

 

[XEagleDriver]

"What are the similarities and differences between surround sound and stereo?" - this is in regard to music technology ***

Approaching the subject from a slightly theoretical perspective, the following comes to mind.

Similarities:
1) Both work to create the same intended effect, i.e. create a 3-dimensional sound stage for the listener.
2) Both use the same basic technological architecture, i.e. a source component (AM/FM, CD, DVD, etc.), a pre-amp to decode and adjust the signal, a power amp to amplify the signal, plus multiple speakers to convert the electrical signal into sound.
3) Both are affected by the listening environment (room) in similar ways, i.e. wall/floor/window material, room size and shape, any applied acoustic treatments, speaker placement and spacing.

Differences:
1) SS uses a more complex multi-channel signal.
2) SS uses more speakers and is more costly to achieve similar quality.
3) SS is not as available in the source media as stereo is. In contrast, stereo media is almost universally available (only a relatively limited number of mono recordings in production anymore)
4) SS may use digital signal processing to artifically transform a 2-channel stereo signal into a multi-channel signal (although many folks don't care for the result!)
5) Stereo PCM is a more established standard then the many SS varients (multi-channel PCM, Dolby, DolbyTrueHD, DTS, DTS-HD MA, etc.)


Hope that helps and good luck,
XEagleDriver