LISTEN OR DIE
Audio is so integral to Alien: Isolation’s suspenseful gameplay, it demands the player keeps their ear cocked for survival.
Story: John Broomhall
Extreme unease, spine-chilling suspense, oppressive fear, sudden terror — all in a day’s work for Byron Bullock, James Magee, Haydn Payne and the rest of their audio team who, over the last two years, have had the gratifying vocation of peddling audio anxiety for a living.
The critically lauded, yet terror-inducing fruit of their labour is Creative Assembly’s horror title Alien: Isolation. It’s a videogame incarnation of a world set in a time just after Ridley Scott’s Alien. The movie was famed for harnessing the power of sound to frighten the living daylights out of moviegoers, but hearing an alien walk the same Sevastapol space station corridors knowing it’s hunting you, that invokes a new level of fear. It’s so scary, players recording YouTube walkthroughs of Alien: Isolation, who know they’re not actually in the game themselves, spend hours in a virtual crouch position peering out of doorways and over in-game furniture listening for the sound of their tormentor.
Byron Bullock: I’ve never played another game that encourages you to think about audio so extensively. The alien uses sound as a primary hunting sense, so you always need to be thinking about how much noise you’re making. We even track your real-world sound using the Microsoft Kinect and Playstation camera hardware, so if you scream on your sofa you’ll give away your position in-game!
You’re constantly questioning if it’s safe to run. Are you going to attract the alien if you use a weapon? Plus sound can work to your advantage as a distraction — say deploying an IED or just hitting things with your claw axe. Imagine your way is blocked by a group of hostile humans. Make some noise, then hide whilst the alien comes and rips that group apart for you! Of course, now you have to safely evade the alien yourself.
We encourage players to listen carefully; sound is one of your greatest weapons and best lines of defence. It can tell you how far away the alien is, if it’s in the vents or on the same level as you. Its vocals can communicate its awareness and the motion tracker reveals any movement around you with a familiar and disconcerting blip.
AT: Did you define an overall ‘audio style guide’?
Bullock: The art direction was tagged LoFi SciFi, a term used to describe the analogue, push-button world of Alien. The game is set just after the events of Ridley Scott’s 1979 movie, one of the first to portray space in this used-up, industrial ‘truckers in space’ way. It’s a time of CRT monitors; no holograms or flat screens. This obviously dictated the audio direction, everything needed to have that tactile feel and lo-fi vibe. Some of the most iconic sounds in the film are things like the mechanical ticks and beeps of the ship’s AI.
AT: How does the audio in a game like Alien: Isolation actually operate?
Bullock: We can play around 100 voices at any one time. A voice is one sound, a footstep for example, a door close or a dialogue line. This may sound like a lot but a gunshot might be made up of multiple voices; the main shot sound, mechanics like the trigger, a 5.1 reverb and reflection tail, bullet drops, low frequency sweeteners, projectile flight, impact sounds, the character’s clothes, a vocal reaction and any other effects like ear whine. It adds up!
We can place sound in the game-world in real-time, attach sounds to objects that move, and mix all those voices live at run-time using various real-time DSP like EQ, compression, limiters, etc. We can script logic to determine how and when sounds play and deliver mono through to 7.1.
“We even track your real-world sound, so if you scream on your sofa you’ll give away your position in-game!”
Game sound is very non-linear, highly interactive and dynamic compared with film. In film you know exactly what’s about to happen; you can set up moments, and sculpt the sound-scape around them. That’s very hard to do in a game. Mostly you don’t know if and/or when an event will trigger; so you have to create systems, rules and logic that work dynamically.
This is especially true in a game as interactive as Alien: Isolation. We aimed to sculpt audio the same way you would in a film to create the high tension and suspense so crucial to horror — but we had an unpredictable, cleverly adaptive alien AI using its senses to hunt the player down. It could hear the player, see the player and any light emitting from their torch. This was a problem for the sound department. We needed to know when the alien would attack and preempt that moment in order to build suspense and tension.
WWISE CAGE MATCH
James Magee: We have several audio systems at work, designed to enable an immersive, reactive and dynamic sound experience, responsive to this emergent gameplay.
We used Audiokinetic’s Wwise sound engine and developed bespoke tools to interface with it. Scripting was done through a powerful in-house game editor developed for the project called CAGE. This gave our sound designers the same tools as the level designers, enabling complex visual scripting and access to real-time data to drive the sound.
One of our most significant audio systems was based around the concept of sound networks, a way of intelligently and automatically sub-dividing the world into different acoustic spaces. Sound networks were primarily a means of ‘cheaply’ calculating high-quality Obstruction/Occlusion, but also allowed us to attach parameters to run other environmental systems such as reverb and ambience.
Our AI systems also made use of sound networks to affect logical sound representations, meaning they ‘heard’ sound in the same way as the player. We made use of this through Stealth and Threat parameters calculated from the AI’s awareness level. For example, as the player makes noises the alien can hear it based upon the surrounding environment.
This real-time data was incredibly useful in driving many RTPCs (real-time parameter controls) within Wwise to emphasise mix elements, eg. bringing the sounds of the main character Amanda and the alien to the fore while ducking or filtering ambient sound to create focus and anticipation in certain moments.
AT: How do you integrate music soundtrack in a world where environmental sounds are so important to the gameplay?
Bullock: We constantly assessed how each sound would make the player feel. That often meant sounds would take on tonal and sometimes musical characteristics.
Early on, we made a conscious decision not to have wall-to-wall music. That’s not to say we didn’t like the music — our composers did a fantastic job! — but we wanted the soundtrack to have contrast and dynamics. You don’t get used to music playing, so it has impact when it does.
Some of the best audio moments are quiet ones without music — you walk into a dark corridor, it’s all quiet except for something moving in the dark. All you can hear is yourself, the walls creaking and some unexplained movement, it’s really tense.
Also, sound can add a sense of realism which can shock people. The sound of the alien ripping apart someone as they scream loudly from the other end of a dark corridor will instantly put you on edge. That moment doesn’t need music — it would feel less real.
Magee: Using parameters such as Stealth and Threat, plus ‘Obstructed_Distance_To_Alien’ gave us tools for a highly dynamic music system. We wrote a custom Wwise plug-in that allowed us to pack three stereo tracks into a six-channel file, which can be mixed at runtime. These tracks were composed ‘vertically’, so when a threat draws closer or becomes aware of the player, the music layering system can dial up the suspense.
Haydn Payne: During encounters with the alien we usually play one of our pieces of suspense music — mostly orchestral but with some synthesised/sound design elements. We fade each of three group layers up and down in real-time according to game events. For instance, if the player is hiding in a locker, the music will sound almost ambient with the alien in the distance, but as it approaches, the intensity of the music rises and the high strings will become loudest as the alien walks right past you.
If the music always responded directly to the alien’s proximity it could harm the game-play by giving away his position too easily, so throughout the game we change how we control the parameter that fades the levels up and down.
One of the alternatives is the music reflecting the degree to which the player is being stealthy by using code to calculate how close unaware hostile enemies are, increasing the tension level as the player sneaks close to them.
We can also script the music to change in different ways when the player sees particular objects or characters — say playing a sting when the alien walks round a corner into view, and subtly increasing the volume of the music as the player approaches a particular part of the environment.
A lot of this is controlled by the enemies’ AI state. As the alien charges to attack we usually trigger a short music riser which builds up to the point when the alien reaches the player. We also use the AI state of the hostile humans to control action music, which has three levels of intensity we switch between based on how aware the hostiles are and how much danger the player is in.
Bullock: We’re constantly asking ourselves, what should the player feel and how can we achieve that? For instance, layering subliminal non-literal sounds underneath real-world sounds to give them an emotional connection; like adding alien hisses into steam blasts and doors closing, or alien screeches into fire bursts and metal corridor groans. We did that sort of thing a lot. It helps to keep the player on edge. The player thinks they heard the alien — or did they?
Sound can be a great tool for misleading the player and at the same time it’s great for doing the opposite, leading the player. Sound can direct the player to a certain area or tell you what’s happening behind a door, like someone screaming in the next room. All these off-screen sounds can tell a story in their own little way and ultimately contribute to the greater narrative.
RAIDERS OF THE LOST ARCHIVE
Bullock: We tried our hardest to get as much original material from the film as possible but you have to remember Alien was made a long time ago on analogue reel-to-reel machines. Fox was very helpful and sent someone down to their archives deep beneath the LA Fox lot to dig up a box marked Alien, which contained an 8-track analogue tape reel. No one knew what was on it. We arranged for it to be digitised and sent over electronically — super exciting!
Opening the tracks in Pro Tools, to our surprise and delight we found some of the original sound effects used to underpin the film score. It was a gold mine! One of my favourites was what we eventually dubbed the ‘Space Whale’ — a low moaning-type sound you hear over Alien’s opening logo.
I love that we’re able to introduce this original content that’s sat there for 35-odd years to a new audience. It really gives the game an authentic feel.
KNOWING THE SCORE
AT: What’s the division of labour amongst the composing team ?
Alexis Smith: Christian Henson initially concentrated on the orchestral elements, while Joe Henson and I focused on the more electronic side. Although there was a lot of cross-fertilisation. We worked on it for about a year and a half and composed about 200 minutes of music in total, but most of it is in a kind of interactive kit form, as the game-play can be 7-20 hours, depending on the player.
Joe Henson: We’re all massive fans of the original film; one of the few we still watch a couple of times a year. It was a great honour to be able to use some of Jerry Goldsmith’s themes, as it never really works when you pastiche something as familiar as Alien. Alexis Smith: Creative Assembly licensed about 10 minutes of the original score that contained the most recognisable themes, which we then re-arranged and re-recorded in various ways.
AT: How did the interactive nature of the music score affect your approach?
Joe Henson: We always start off by writing a piece that can stand up by itself. After that we can work with the interactive engine. It is a bit of a puzzle, but one that is really rewarding when it works well!
We recorded a lot of it in our own studios. We have a large collection of analogue synths and weird home-made instruments and try and play as much as we can ourselves. The orchestral recordings were done with Jake Jackson at Air Lyndhurst with the Chamber Orchestra Of London. We were lucky enough to have some of the players from the original score, who were very informative on some of the techniques used.
MAKING MOVES: RECORDING FOLEY
Alien: Isolation’s foley was recorded at Shepperton Studios by Head of Digital Recording & Editorial for the Pinewood Studios Group, Glen Gathard. You’ll have heard his work in movie blockbuster franchises like Batman, Bond and Harry Potter.
Glen Gathard: It’s all about organically recreating the sounds needed to bring a scene or game to life, ‘performing’ the sounds as if you are the person onscreen. Foley can add to the emotion of the person you’re performing — Alien: Isolation is a perfect example. The footsteps across all surfaces were thought about from different emotional states — if you’re scared, the feet will be light, stealth-like with random imperfection — plus additive layers like scuffs and squeaks.
The cloth and equipment layers work similarly — when hiding you want to keep noise to a minimum; having cloth and item detail heightens the silence — if all you can hear is your clothing, a little dog-tag rattle and light scuffs underfoot, everything feels quieter and it builds suspense — it’s more claustrophobic; and then the big scare moments with the alien feel much, much bigger.
Shepperton’s foley theatre is one of the very best in the world. There’s nothing we can’t do, from high heels on wood, flooding the surfaces with water to dripping molten fire plastics from a step ladder. It’s a massive playground full of people that truly love the art of foley and sound design.
I’m also a massive gamer lucky to cross the world of film and games quite frequently. Since working on games I’ve learnt so much, and hold videogame sound designers in high regard. To create sound for a project that will be played over and over again — and to keep it feeling cool, fresh and dramatic is such a talent.
James Magee: Our foley system was an attempt to push the boundaries of what could be achieved with real-time information. The in-game stealth mechanics mean you’re aiming to make as little sound as possible while trying to survive, and dynamic foley really helped this feel credible.
Real-time player input completely drives Amanda’s foley system through a combination of Movement_Speed and Acceleration RTPCs, rather than the traditional approach of tagging her animations with event metadata. For example, as the player moves Amanda around, we apply the Movement_Speed parameter to a blend container which crossfades between slow walking and running foley one-shot samples. Each time a footstep is triggered by code, we also trigger a foley sound event which activates the blend container, resulting in the right foley sound playing back.
We detect the acceleration of the first-person camera movement so when the player quickly turns Amanda around to see some unseen horror behind her, the Acceleration RTPC triggers a foley sound through a Wwise switch to simulate clothing movement. It’s a subtle audio system but adds a lot to connect the player’s input to the character — especially effective for a first-person survival horror.
TIPS & TRICKS: CAPTURING SOUNDS
Haydn Payne: Some of our computer sounds were made by creating a software synth that generatively plays sequences of beeps of random pitch, duration, waveform, and delay settings. We made long recordings of the synth’s output as it ran continuously and edited together any bits that happened to sound good. The resulting audio was too clean compared to the lo-fi analogue quality of the computer sounds from the film so we fed them through various tiny damaged speakers taken from broken toys and recorded the results.
Payne: When the alien charges at you, the audio system detects its speed is above a certain threshold and triggers running samples for its movement. If the threshold is not reached it plays separate walk samples which are dynamically mixed quieter and with more low-pass filter relative to the movement speed decreasing. Each walk footstep sound is made from two parts — the claws hitting the floor and the weightier foot impact. When the walking speed is fast the two parts are played in quick succession but as the alien slows down, the delay between the two parts gradually increases — there’s a noticeable gap between them at the slowest movement speeds.
Payne: The vocal sound the alien makes when it has heard something suspicious is different from when it’s seen a target, or has lost track of its target and so on. The alien’s language in its different states can be learnt by the player to understand more about its behaviour. The sound design for this drew from a variety of source material including the sounds of big cats, reptiles, pigs, bears, birds, and the human voice.
Bullock: We used a coil pickup microphone which captures changes in electromagnetic signals and turns them into audible information to record all sorts of computer and static sounds. However, my favourite came from my fiancé’s heated rollers. She has a machine that heats the rollers instantly using induction technology. I put the microphone inside this contraption and got the most insane electrical blast sound which we used in several places, most noticeably in the reactor levels as part of Sevastapol’s energy core.
DRY ICE INTERFACES
Bullock: We used contact microphones and a hydrophone to capture dry ice and metal vibrations for Sevastapol’s metal interior and did some circuit bending to generate interesting electronic sounds for interfaces.
CONDOMS & INTERNAL ORGANS
Bullock: We submerged a trusty SM57 (inside a condom) into a bucket of slime (lots of different food and drink mixed together) and got some great internal organ sounds for the alien.