I often use a software program called Audacity to fix problems in audio files. There are lots of other programs you could use, for example, Sound Forge, Sound Edit , Cubase VST or ProTools .

Audacity is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity to:

• Record live audio.
• Convert tapes and records into digital recordings or CDs.
• Edit Ogg Vorbis, MP3, and WAV sound files.
• Cut, copy, splice, and mix sounds together.
• Change the speed or pitch of a recording.
• See the complete list of features .

Audacity Interface. Click on the Image for
a closer view