+1 for MP3Gain and +1 for backup your files first.

Mp3Gain is not a normalizer but does exactly what you are looking for. It will batch process an entire folder or individual files.

By default, it levels all files to 89dB but that figure is user adjustable. It also has an "analyze" mode that shows the status of the files before processing.

Last edited by Don Gaynor; 07/10/12 07:32 AM.