Why are my encodings soundless?? (L4D Video Sample Included)

The Problem: I'm encoding videos in Adobe Media Encoder, and the video looks great, but the audio sounds horrible, even though on the source file, the audio is perfect. What do I do?? I acquired the source footage with Fraps. In the uncompressed Fraps version, the sound is perfect. Every time I try to encode it, I get the horrid noise you hear in the video, and then silence.

My hypothesis: I'm guessing it has something to do with the source file, as I've encoded other videos with the same audio settings as this, and the audio turned out ok. But what could the difference by?

Here is the video: http://www.youtube.com/watch?v=BoINbhLCdrU

and here are the settings I used in Adobe Media Encoder:

Video Settings:
1280 720 ntsc
Fieldorder: lower
Pixel aspect ratio: square pixels
Profile: high
Level 3.1
Vbr 2 pass
Target bitrate: 5
Max bitrate: 7
Framerate 29.97
Mainconcept h.264 codec

Audio Settings:
Audio Codec AAC
Stereo
Frequency 48khz
Bitrate 192kbps

What's going on!!??