problem with distortion when reducing tempo

Hello! Im using Windows 7. Im new to Audacity, so please forgive me if this is question is somewhat basic.

Im using Audacity to edit some voice recordings, and I used the "Change Tempo" effect to slow down some parts that were spoken too fast. Then I exported the project as an MP3, but when I played back the MP3, it was sounding very bizarre, the voice all distorted and slowed down much more than it had been when I had originally played it back in the program. I am not even sure if the problem is the "change tempo" effect, as the distortion seems to me to be affecting some other parts to which I don't remember applying the effect, but that's the only idea I have for what the problem I could be. Other than that pretty much the only editing I did was cutting out some parts where there were mistakes. Id be most grateful indeed for any suggestions about how to fix this and how to avoid it happening! Have a nice day :smiley:

Was the original an MP3? You can’t easily edit and do production in MP3. MP3 works by damaging the sound and then cleverly hiding the damage so nobody notices it. If you edit an MP3 and make another one, you make it a great deal harder to hide the damage. If you then apply an effect which is trying to play the same digital tricks, you could easily make trash.

There is no recovery. MP3 damage is one-way and permanent. We recommend you do all production in WAV (Microsoft) 16-bit and then only make an MP3 at the end if you have to.