Enable 3D Surround Sound for Stereo Headphones

Learn how to upgrade your copy of OpenAL and enable HRTFs so that you can experience more immersive, accurate, 3D audio in Amnesia: The Dark Descent.

Introduction

Once you've followed the instructions in this guide, you'll be able to experience Amnesia: The Dark Descent with accurate, 3D surround sound using only your stereo headphones. Sounds coming from in-front and behind will be distinctly different and even sounds coming from above or below will be clearly discernible. It will feel more like listening to reality than a video game.

Amnesia: The Dark Descent uses OpenAL for rendering audio. The OpenAL driver that comes with the game is the same one that is distributed with a standard OpenAL installation, which happens to be a pretty shoddy implementation of OpenAL. We'll replace it with a better version called "OpenAL Soft" and configure it to enable HRTFs.

(If you're interested, there's information about what HRTFs are in the Further Reading section.)

How-To

• Download OpenAL Soft

  OpenAL Soft has a fairly modest-looking website, which you can find here[openal-soft.org]. For your convenience, here's a link straight to the download of the current version at the time of writing this guide:
  > Download OpenAL Soft 1.15.1[openal-soft.org]
  
  

• Unzip the archive

  
  

• Install OpenAL Soft into Amnesia

  You'll see a bunch of folders after unzipping the archive but we're only interested in the file called soft_oal.dll inside the Win32 folder.
  
  
  • Right-click on Amnesia: The Dark Descent in your Steam games library and click Properties.
    
  • Click the Local Files tab.
    
  • Hit the Browse Local Files... button. An Explorer window will appear showing the contents of the Amnesia game folder.
    
  • Copy soft_oal.dll from the Win32 folder into the Amnesia game folder.
  
  

• Enable HRTFs in OpenAL Soft

  We need to create a configuration file that will tell OpenAL Soft to use HRTFs.
  
  
  • Open Notepad
    
  • Type the following:
    

    hrtf = true

  • Click the File menu and Save As...
    
  • Type %APPDATA% and hit enter. It will automatically take you to the folder where we need to save this configuration file.
    
  • Change the Save as type drop-down list to say All files (*.*)
    
  • Type the File name as "alsoft.ini" and click Save.
  
  

• Set Amnesia to use OpenAL Soft

  Start the Amnesia Launcher and click on the Sound Options tab. There should now be a new Device available. It should be listed as "(Unsupported)" followed by the name of your default playback device. Select it.
  
  Don't worry that it says Unsupported. It just means that the developers haven't tested it. It will still work, though.
  
  

• Play Amnesia!

  At the beginning of the game, there is a perfect spot to test if HRTFs are working. When Daniel wakes up, there is a stream of water dripping down onto the floor next to him. Stand near the stream and look around. You should be able to hear the sound changing and it should 'feel' like the source of the sound is moving around your head. If you face the stream of water and look up and down, there should be distinct changes to the sound that wouldn't normally be present with the default OpenAL driver.
  
  Enjoy!

Further Reading

What does HRTF mean?

HRTF stands for Head-Related Transfer Function. In fairly layman's terms, it represents the changes that occur to a sound when it interacts with your ears and head before reaching your ear drum.

More on that here: Wikipedia: Head-related transfer function[en.wikipedia.org]

What about Dolby Headphone?

Products like Dolby Headphone, Razer Surround and Creative CMSS-3D provide a similar surround sound effect for headphones. The difference is that they use a pre-mixed 7.1 or 5.1 channel audio stream as their source input. This limits the accuracy of the sound localization to those 7 or 5 points in space. Additionally, they have no support for sounds coming from above or below because 7.1 and 5.1 systems do not have speakers above or below the listener.

OpenAL Soft is different. It doesn't receive a pre-mixed audio stream as its input because it is actually serving the function of the mixer itself. Therefore, all the precise coordinates of all the sounds in the game are available to OpenAL Soft.

CMSS-3D is an exception because it works with Creative's OpenAL driver and can have access to all the precise coordinates to provide fairly accurate sound localization. However, it does a terrible job of sounds coming from above and below, which is probably why they have a special option for turning the "Elevation Filter" on or off.

If you have a sound card or headphones that support Dolby Headphone or any other virtual surround sound system, you need to turn those features OFF when using OpenAL Soft.

What about Rapture3D?

Rapture3D is an excellent 3D audio system made by Blue Ripple Sound[www.blueripplesound.com] that also provides fantastic headphone surround sound (amongst many other cool things). I personally think that Rapture3D is the very best 3D audio system available but I decided to focus this guide on OpenAL Soft because Rapture3D is not free. It costs about the same as a full-priced game and I highly recommend it if you're into 3D audio.

Rapture3D can be used with games that use OpenAL in the same way that you use OpenAL Soft. However, it is recommended that you follow the instructions on their Compatible Games[blueripplesound.com] page instead. They're slightly more complicated but work better for Rapture3D specifically.

This sounds amazing!

I know, right? It's a pity that most games don't use OpenAL and don't provide any built in HRTFs for headphone users. Read my rant on this matter on my blog:

> I Want HRTFs In My Games![matthewkerswill.com]

What about 7.1 & 5.1 speakers?

The default OpenAL driver actually has very iffy support for surround sound speakers. Users of 7.1 and 5.1 speakers can also benefit from using OpenAL Soft instead of the default OpenAL driver. You won't need to enable HRTFs for speakers, though.

[pear]

Creative Alchemy can be used to force OpenAL when the game (or games) refuse to load the .dll

[Terepin]

I dunno man. It sounds good on paper, but every single virtual surround system distorts mono sounds and I hate it. This one is no exception.

[Ketesi]

Note to Linux users:
As far as I can tell, OpenAL Soft is the default.
Also, the device doesn't show as unsupported, presumably because of this.

As for the 'alsoft.ini' detail; if /etc/openal/alsoft.conf exists, that's the one it's reading.

An easy way to check if that's actually being used is to run the NO_STEAM version (included with the game) from a terminal after making sure that in the [general] section, frequency = 4000.
OpenAL Soft will output:
AL lib: (EE) alcOpenDevice: 4000hz request clamped to 8000hz minimum
Which means it absolutely definitely did read the file.

This said, I haven't done a comparison to tell if HRTFs are enabled or not.

[svfn]

@WildCat, thanks. yes i have tried the older OpenAL Soft previously. it only worked after i installed Creative x-fi mb3. so now it shows unsupported new device OpenAL soft like you mentioned in the guide, so i'm guessing it worked after all. i need to listen more closely to notice the difference. now i want to try other OpenAL / EAX games!

[WildCat]

@svfn - It's been a long time since I wrote this guide and I don't know if a change in either Amnesia or OpenAL Soft might have rendered these instructions out-of-date. The only things I can really suggest are:

1. Try 'installing' OpenAL Soft into Windows by following the instructions provided along with the download. It basically involves copying the DLL(s) into your Windows System32 and/or SysWOW64 directories. The latest versions of OpenAL Soft will also involve copying some files into a new directory called 'openal' in your %APPDATA% directory.

2. If you used the latest version of OpenAL Soft, try instead using OpenAL Soft 1.15.1 (the version linked in the guide) instead.