Why do I have staticy sound?

Because you seem to be having a unique experience with this, I think the following things are worth looking at, just as a bit of a check list.

1. Is anyone else having the same problem?
2. If you use other Headphones/speakers does the problem persist.
3. Does dropping the total volume help? (In game and in Windows Sound Manager)

The above three will help you identify where in the chain the static is coming from.

Question 1:

• Yes? Problem with the game
• No? Problem with your hardware/software

Question 2:

• Yes? Headphones/speakers are damaged.
• No? not your headphones/speakers.

Question 3:

• Yes? The Sound card has a maximum amplitude that it can output, you are surpassing that, and as such your sound card (or other sound output device) is not powerful enough to drive your speakers/headphones at the volume you are trying to achieve. (Fix and then test Question 2 again, your light headphones, will behave differently from your heavy speakers)
• No? Something between the software and your hardware is not playing fair. If the problem is unique to this game, blame the game! If it's happening for more that just this game (try running some others at full volume (max it out)) then blame the drivers/hardware

If you're using a built in sound device (can still do if you don't mind replacing your existing PCI card): Find a local tech person and ask them if they have a spare sound card (These are practically junk PIC cards that most people never need/use so they just pile up.) Give him a $20 and ask him to throw it in your PC. (PS: Woot upgrade :) ) See if that fixes the issue, if it does, blame the original card for having limited scope, bandwidth, power, or just wearing out. If this does not fix the issue, (New Hardware, New Drivers, Different Headphones) Then the only options left are 'Your game' and 'Your Operating System' If it's windows, blame windows. Else blame the game.

Side notes: "win+r" -> "dxdiag" has a sound section that can give you some details about your sound device.

My question to you:

Is this custom audio files that you placed in the game folder? And if so, did you have to convert the audio files to .ogg?

If your answer is "yes", then I know a possible solution:

Yesterday, I had been having trouble with audio files in-game (Not Mount and Blade, but the premise is still the same). What had happened is that after audio conversion, and after launching the game, the custom audio files that had been converted to .ogg file format began having a loud staticy sound, so much audio interference that I couldn't make out what audio file was actually playing.

But I later realized that the problem didn't lie in my hardware or drivers, but rather in the conversion process itself. During the final and additional options directly before the conversion process, I had not seen that you had the option to choose the "sound rate" at which the audio files were converted. But I tested this theory, and converted another single audio file, and the sound rate (Hz) that I selected the file to be after conversion was "44100 Hz". Because this is the default audio sound rate for default audio files on the majority of modern PC's and other hardware. I launched my game, and tested the newly converted audio file, and the audio file played perfectly and clearly with 0% static or any other type of interference.

So, in simple terms, the steps to be taken in this situation are as follows:

1. Convert audio file(s).

2. At the last step before the conversion process starts, select the sound rate "44100 Hz" for all audio file(s) that are to be converted.

3. Place audio file(s) in their designated folder, unless you have already chosen the designated folder as the audio file(s) output directory.

4. Launch your game and test the audio file(s), if the audio plays clearly and without interference then you have solved your problem. If not then there is another reason for your audio having static interference, and is more than likely a hardware or driver issue as stated by TolMera above.