Hi @Lisa Welcome here, If you mean that one audio file is to loud and the other to soft (say less in DB) There is a similar topic here: Getting mp3s to be the same volume
If the audio is bad in sound, crackling background noise and so on, maybe the explanation from me in this topic can help you out: Remove noise old record
I hope this will help you to solve your problem, otherwise please upload , as Mike also said, your files