Ljud Tips: Om du har 5.1/7.1 stäng av fake Susround sound

This setting determines the dynamic range of your audio, i.e. how loud the loud and quiet sounds need to be. It is completely independent of the number of speakers you have.

Hi-Fi assumes average-quality desktop speakers or headphones. Nothing special, nothing horrible. "Hi-Fi", psychologically, just sounds nicer than "default".
Home Theater assumes high-quality speakers or headphones with great signal reproduction. Lows and highs do not need to be boosted for your speakers to render them.

Small Speakers is intended for cheap-o speakers - dollar-store 2.0 setups, earbuds less than $25, and so on, which generally have poor reproduction of low and high frequencies. If you have good speakers, this setting should lower the quality of your sound. On the other hand, if your speakers are small and cheap, it will make the low/high frequencies audible.

Headphones is intended for, well, headphones I suppose. I don't notice any real difference between this and Hi-Fi, but I've only ever enabled it once.

War Tapes applies virtual compression to the audio, mimicing the way a human ear drum/canal would react to it. Without getting too deep into technicalities which I don't actually understand, it's basically "HDR audio". Quiet environments cause quiet sounds e.g. footsteps to be boosted to high volume, while a sudden explosion will both drown out the footsteps and, afterwards, leave you with a second or two of "shellshock" where quiet sounds continue to be muffled.

[Note:] Switching to War Tapes from another setting generally makes the audio seem much louder.
[Another note:] If you have tinnitus, War Tapes is invaluable for getting quiet sounds to out-compete the ringing in your ears.

ENHANCED STEREO
This setting determines whether BF3 "fakes" surround sound for your 2.0 or 2.1 setup, be it speakers or headphones.
Some newer sound cards, like the SB Audigy series, let you enable driver-level virtual surround. This, in my experience, produces higher-quality spatial positioning and waveform mixing than BF3's Enhanced Stereo (though it may lead to increased CPU usage). If you plan on using this, do not use Enhanced Stereo, as it will crush the audio to 2 channels before your soundcard is able to do its surround sound mixing.

Consider the following signal flow:
Game -> Windows -> Sound Card -> Speakers

1. Figure out what kind of speaker setup you have. Headsets that do "virtual surround" are generally equivalent to 2.0, while headsets that simply do "surround" are 4.0 or 5.1. However, some "virtual surround" is advertised as "surround" and vice-versa. Please refer to the manual to be sure.

2. Set Windows to use up to this many speakers, if your soundcard allows that many, i.e. don't set it to 5.1 if all you have is 2.0 headphones. Rightclick taskbar volume icon, Playback Devices, speakers, Configure.

3. If Windows didn't let you enable enough speakers, either reinstall your sound card, or match your number of speakers to the Windows settings (and make sure they're properly connected!)

4. If you are using virtual surround, enable it in your various drivers and control panels (if necessary).

5. Check your sound card's settings/control panel (if it has one) to ensure that Windows configured it with your new settings.

6. Start BF3 and select the relevant Enhanced Stereo setting.

And you're done! Your surround sound should now work properly for all games, so long as they have the right in-game settings too.