Wednesday, November 22, 2006

Virtual Surround Sound

It is popular belief that the best Home Cinema Sound Systems are the ones with the most speakers. Indeed the move from Mono to Stereo and Stereo to Tweeters/Subwoofers has indeed increased sound quality and this has all been very beneficial to consumers. I personally believe the advent of the Subwoofer is directly responsible for a radical change in rock music as many classic rock tracks including heavy metal from the 80's is mostly without base. Where as modern rock is mostly about thumping base and many genres like Trance wouldn't exist without the mighty base sound of a good sub. Surround sound has benefited films for many years now and as a result there is this thing called 3D or Virtual Surround Sound that has reared it's head that says you can get the same Surround Sound experience through two standard speakers as you can through five or six.

The idea of invisible speakers has intrigued me for a few years now. Our brains only receive sound in stereo, so it should be possible to have a surround sound cinema experience with just two speakers and there are systems out there that do this. Yet I have previously lacked anykind of 3D Speaker setup and haven't been able to play around with one. But have been eagerly awaiting the day when I could experience a Virtual Surround Sound Experience, until now.

So let me just step back a second and cover this a little. Most 3D Sound systems work by way of Head-Related Transfer Function which is a fancy way of saying that your Brain knows where some sounds are coming from because of the way the soundwaves hit your ear-drum. This is best heard for yourself and you can do that with This Dolby Flash Demo.

So anyway to explain this in english:
What the Virtual Surround systems are doing is taking a 5.1 surround output from a DVD player (or whatever device) and applying different sound altering algorithms to the different audio channels so that when all the speaker channels are played thought just two speakers the background sounds still sound like they are being playing behind the listener. The soundwave distortion effects that happen to the soundwaves as they travel from rear-speakers to the listener's ear-drum have been applied by the Virtual 3D Sound System's sound altering algorithms. So no the sound doesn't come from an invisible rear speaker, but it sounds like it does.

So that brings me to today and to cut a long story short yesterday I got a copy of PowerDVD7 that supports several types of Virtual 3D Surround Sound. I have played with it, and this now allows me to conclude some finding.

Virtual Surround Systems supported by PowerDVD7:
  • TruSurroundXT with TruSurround, Digital Clarity Enhancement and TruBass
  • Dolby Virtual Speaker
  • CyberLink Virtual Speaker
To test this out I used the opening sequences from Lost In Space (talking followed by lots of deep explosions and general space ship dogfighting), Akira (musical sequence with bike racing) and I watched the entire Animatrix (just to check my findings). I tested with my 2.1 Creative set of speakers and a set of old Earbuds.

All SRS Labs does is virtual sound technology and was the first company setup to specifically do this stuff so I was expecting this system to be the best. But it butchers the audio to an unacceptable extent. If I just talk about the individual features for a second. TruBass applies base to stuff that shouldn't have it, DCE which is supposed to make voices easier to hear dampens some background sounds and TruSurround's Base doesn't stand on it's own because it relies on TruBass. TruSurroundXT makes for a much better cinematic experience through the crappy Earbuds, but I would rather have the system turned off and listen to the standard Stereo audio than have the films audio track bastardised like it is with TruSurroundXT.

Dolby Virtual Speaker
The best system, I get that 'more sound' feeling when contrasting it with standard Stereo and the sound envelops me like when I am listening to a true 5.1 system.

CyberLink Virtual Speaker
Very good, similar to the Dolby, but some frontal sounds have more base applied to them than what is necessary.

Virtual Speakers aren't yet as good as having a true 5.1 surround system, the sweet spot from a 2 speaker setup is much smaller and somepeople will hear 3D sounds from strange places as everybody's ear channels are different with the 3D Sound Systems only mimicking the most common shaped ear canals and there are a few other things that the brain uses to locate where sounds is coming from that we don't understand yet. So all that is probably why DVD Stereo tracks don't come with 3D sound pre-applied. But for me I am going to leave my settings firmly on Dolby Virtual Speaker as I don't have the space required or the money for a 5.1 Surround setup. Also when I am watching a film at night I can now get a surround sound feeling, with just my earbuds!!!