Help! Sound quality issues

Yesterday I edited my file, I exported to Mp3 within audacity and all was well. I listened to it several times over and the sound quality was great. Today, I open the file again and the sounds is awful. The background is fine, but when the speaker speaks it sounds strange. It’s hard to describe but the closest I can come to describing it is if two people were speaking. It sounds like there are two of him and one is just a bit off so the clear crisp voice quality is now messed up. Does this sound at all familiar? Is there anything that can be done?

Yes I know that well - but more commonly when mixing tracks. Working intensively on the same thing for long periods it is easy to become too involved and loose objective awareness. If it’s late at night, back up everything, go to bed, and come back to it tomorrow.

You also exported a WAV version of the file?

Open the WAV version and Export it again as an MP3, but use higher quality settings. 128kbps is the minimum that you should be using for high quality music. (Standard quality VBR is better). 64kbps should be fine for a mono recording of speech.