convert MP3 creted to au files

I converted a lot of my old cassattee tapes into mp3 audio files using Audacity old previous version 1.2.6(? the one before v2.0) but I did not remove background noises generated by runing recording on cassatte tapes before converting. I do not want to run cassattee tapes again to convert them to mp3 after removing noises using audacity v2.0. I want to convert mp3 into temporary “au” files so that I could convert them to mp3 after removing noises under Audacity v2.0.

I could not find any software to convert mp3 to au files, similar created by audacity v2.0, which generate sound pictures on the computer screen for me to remove noise. Is any way I could convert mp3 files to au files which generate sound pictures for me to play removing noises?

Never do production in MP3. MP3 creates distortion every time you make a new one, so when you clean up in audacity and make a new MP3, the MP3 may have more distortion than the original.

You should not worry about the AU files. Those are internal Audacity housekeeping files and not all of them are sound. When you get one show ready to save, File > Save As and pick a project name for the work. Audacity will create an AUP file and a _DATA folder with the same name. That’s one Project. never separate them.

Or you can File > Export as > WAV Microsoft 16-bit PCM. That is a very high quality digital audio file and it does not have any of the problems MP3 does. But is very much larger. Many of use that as the archive format. Some people use FLAC which has similar sound quality but smaller files. FLAC files will not open everywhere.

You can make all three.

Then, at the end of all that when you want to listen on your Portable Music Player, that’s when you make an MP3. But keep the WAV files around as an archive.