I have speakers in my backpack, powered by 3 AAA batteries, that I plug into my iPod. I have about 20 minutes of police/military-style radio chatter with distortion that I play in a continual loop on low volume - sounds just like a police scanner. It's from a sci-fi video-game (can't remember which one) and there's even one part where the C.O. can be heard on the radio saying "Move along, move along." The chatter also mentions shuttles, weapons, "clearing out" residential blocks, hard-points, officer down, lots of radio "10" codes, etc.
If anybody wants the MP3 files, just PM me, and I'll email them to you. They're about 20MB, so I'm not sure where/if I could post them online for download, but I'll be happy to email them to you.