how to remove audio noise from mp4 ?

White noise, sometimes known as "background noise," can be especially frustrating to the person who is making a Podcast or other MP3 recording. Unless you're recording in a studio, it's likely that you are going to have to deal with some degree of white noise, but you can remove white noise from an MP4 file using the open-source, multi-platform software, Audacity.

http://www.ehow.com/how_2273767_remove-white-noise-from-mp3.html, it gives you a tutorial on this!

You can remove white noise from Audio Recordings using the open-source, multi-platform software, Audacity.

http://www.fanhow.com/knowhow:Remove_White_Noise_from_Audio_Recording_19268236

Whether you're dealing with hiss, hum, computer fan noise, or any other constant background sound, Sound Forge 9 software can often reduce it and sometimes, eliminate it

you can use noise reduction tools. for more details, you can go to http://www.sonycreativesoftware.com/news/article.asp?articleid=66