Audio Conversion from RAC .VOC to MP3 for itunes

I have 7 audio files that were made on a RAC digital recorder. They are saved in a .voc format. I need to convert them to mp3 for itunes. I've tried all sorts of converters including audacity but they keep compressing the files from 5 minutes to just a few seconds. I'm sure this is an easy job for someone with the right software. You just need to make sure the files can be played back and that they sound correct. Some of the files are very short but a few are more than 5 minutes.