Friday, 8 May 2009

Stay a while and listen

One of the ways that valve tells a story in their games is by scattering little ‘micro stories’ around the game world, often in slightly out of the way places. If you’ve played any of their games you’ll know what I’m talking about – graffiti on the walls in Left 4 Dead that hint at survivors who have gone before are a great example. In Half-Life 2 there is a small corner in the level “Water Hazard” that I wish to highlight as an excellent example of using sound in a particularly videogame way.

This place, which has no name as far as I know, appears at first glance to have once been another outpost on the Underground Railroad and occurs a few hours into the game. Looking so much like an overnight camp, there are a few scattered supply boxes, a mattress, resistance graffiti and a clutter of other detritus; obvious evidence of human habitation. There is no-one there when you encounter it, but a curious feature remains, giving the location a very unique feel.

When I encountered it the other day, I greedily lapped up the atmosphere. I actually sat and listened for a number of minutes, becoming utterly absorbed in the sound of the place – and more than that, in the sense of place that the unique sonic signature gave to this tiny corner of City 17.

There are a few things I want to note about the sound in this scene, and most obviously anyone who comes across this place in the game will probably be struck first by the ‘wind chimes’. They stand out from the sound of the rest of the game because of their volume in the mix and their distinct timbre. The sound contains a variety of both pitched and unpitched sounds that work to blur the line between musical elements and sound effects. Obviously, a sound doesn’t have to be pitched to be ‘musical’ or to have beauty – the timbre of a sound plays as much a part in our response to sounds as does the fundamental frequency of the sound.

Another feature that adds beauty and a unique sonic signature to this place is the background sound of a constant strong wind. What we call the sound of the wind doesn’t really have a fundamental note that we can identify as a pitch as it is really a complex combination of sounds. Perhaps most importantly, wind doesn’t even have a sound until it blows past an object, and so what we associate with a “wind” sound is actually a series of sounds that will often change and fluctuate in unison in accordance with the wind speed. However, even this ‘sound’ of the wind blowing has a musicality to it – that is, it has musical properties that I find incredibly attractive. In this corner of Half-Life 2, it fluctuates seemingly as if at random, increasing and decreasing in volume and pitch as the speed of the wind changes. There is, of course, no real wind in the game, but the sound is so convincing a recording that I half-expect to feel the breeze on my face while I stood listening to it.

The ‘aural scene’ of the location is reinforced by the visual, that is, the sounds make sense with the visual. The windmill above the player reinforces the notion that there is a strong wind blowing. The audible and the visual combine to reinforce a single impression and it’s all the more powerful and impacting for it.

While the wind chimes themselves arguably become the aural focus in the place because of their prominence in the mix (i.e. they are quite loud comparative to other sounds), they actually have no visible propagating source. Which is an important point to note, as sounds don’t have to have a visible source and leaving their location hidden or up to player interpretation is a completely valid artistic technique. Cinema has used this trick for years, and will often use a sound to tell the viewer about something happening off-screen. With games, however, a developer can rarely ever tell where a player is looking, that is, what is “off screen” at any one time is up to the player, making it difficult to use “off screen sound” in a deliberately artistic way.

What often happens is that the game will spawn an object behind the player or in a location above and out of view of the player and attach a sound to it to attract the player’s attention. For example, in Half-Life 2 there are many occasions in the area around this location where soldiers spawn on bridges above the player.

You might argue that the sound of a gun cocking behind you in a game happens “off screen”, which is true, but strictly speaking, from the point of view of the game engine that place in game exists whether the player is looking at it or not. I’m not entirely sure about this analogy, but to me the equivalent of actual “off screen” in a game would be a sound coming from a place that doesn’t even exist in engine. That is kind of what is happening here, with the sound of the wind chimes and the wind coming from an invisible, virtual location.

The end result of all of the above points is that while technically being sound effects, the wind chimes, and the wind, take on a similar role to what music would – giving the location a very real and specific atmosphere. This blurring of the lines between more pure sound and music is something that I am very interested in, and was a core finding of my research thesis last year. It seems to me to be an somewhat unexplored area ripe with potential.

I hope you’ve enjoyed taking a moment to listen to the sound in the one corner of Half-Life 2 as much as I have.


Simon Ferrari said...

Good shit Ben. First thing I thought of while watching/listening was that it was kind of a sound design counterargument to this:

The opening scene from Once Upon a Time in the West. Note the big difference in how prominent the sound of the physically identical windmill is between the two? One way the film builds tension is in explicitly keeping the sound effects as frequently off-screen, just like how you can't visibly see the wind chimes in HL2.

Jonathan said...

Nice observation Ben, it's definately these little details that make Valves games stand out among the crowd.

I remember that area, remember the desolote abandoned outpost but don't specifically remember the sound of the place, which obviously plays such a huge part in conveying that desolation and peacefullness. So I'm sure I must have "felt" it subconsciously even if I can't remember it. :P

It's probably also worth noting that that section is right after you had been zipping through large canals at high speed, with enemies spawning all around you, rockets hailing down on you and helicopters chasing you and you generally being under alot of adrenaline fueled pressure. So it had that much more of an effect where you could stop for a second and relax. :)

Camilo said...

The atmosphere changes you encounter on Half-Life 2 are unique.

I enjoyed this place in particular much more than any other in the HL saga. The sound-art is really nice, relaxed and calming.

I'm glad I was not the only one who felt there was something special about this small spot.

Jorge Albor said...

I was just playing this part of the game and sped right past this little nook. I actually found the sound and location to be creepy and unsettling.

Great post, I had never thought about off-screen sound before, but its not surprising Valve's non-essentials are superb. I'm particularly drawn into their lighting choices in L4D.

Alan Jack said...

The use of audio is probably the most underutilised area in games next to game design itself, and things like this prove it. A brilliant little moment that proves the power sound can have on the human psyche.