iMovie no audio importing AVI

I have imported 2 AVI files into an iMovie project and they appear to have lost the audio.
I am an intermediate at video editing but not with iMovie as I have just moved over to Macs from PC and this is the only software available to me right now.

Do I neeed to convert my AVI files into some other format so iMovie will retain the audio? If so what would be a good program to use?

Thanks in advance.

After reading various other threads similiar to this issue I believe it can be solved a number of ways.

Convert the AVI file to MOV (Quicktime) file. I happen to use software from AVS4YOU ~ AVSConvertor for PC.

Other solutions point to the video and audio file being mixed down to a single track so you could try and demux it.