Reduce background noise from seminar recording

Hello... I have four .wma files which are recordings of a seminar. All 4 files are 40 minutes long. There is a "hum" in the background - like the recorder was too far away from the speaker. I would like someone to "clean up" these recordings so that they are easier to hear. I have uploaded one of the files to a server so that you can easily download it to hear it for yourself. It is found at... [login to view URL] PLEASE do not bid till you have downloaded the first file and verified that it is a problem you can fix. After the project is awarded I will send you the remaining 3 files. Thank You, Mark