What converter did you use? A few people have had trouble with sound when using Videora. If you did use Videora, these are the settings I've used (I think they're default settings) & had no trouble with sound. Don't forget, you might have to use the wheel of your iPod to turn up the volume!

Bitrate 128kbps
Channels Stereo
Sample Rate Input(default)
Volume 100%

If you're still stuck, use the forum search to look for video to iPod. You'll find other threads to read & also info about other iPod video converters