Recording for AM broadcast

Hello, I record Talking Houses for a local Realtor using the latest stable version of Audacity for Windows Vista. Along with my vocal presentation, I mix in some royalty free music in the background. Due to limitations of the Talking House unit, I must export my project to MP3 format, transfer to my ipod and transfer the project to the unit. Transferring from my PC produces a loud electronic hum. So the project sounds great on my PC and through the internal speaker on the Talking House Unit but when I tune into the AM station on a radio and listen my voice sounds very distorted while the music sounds ok. The music is broken into two tracks from a single stereo track and my voice is recorded in mono. I’ll admit I’m not an expert on audio recording, so I’m asking this forum to help me figure out what I need to tweak in order to get this project to sound clear over AM broadcast. Is there some tweaking needed on the voice track? It doesn’t seem to be a volume issue although I have tried tweaking the volume levels on all 3 tracks. I know the unit is working because when I transfer over a few seconds of a TWiT podcast it sounds great. So my problem is in my recording…the question is what is it?

Thanks in advance for your suggestions.

PS If you want to download the project I have it at http://www.allofjoshua.com/talkinghouse/take1.mp3

In general you are processing to be played on equipment with little Bass and no high treble, so you can filter these out of the recording, and then compress what is left. Maybe remove most of what is below 200Hz and about 5kHz from the recording, then compress at 3:1 ratio from a low threshold to get the level up without clipping the recording.