IT Question Concerning Voice Over PPTs.

[X Ring]

My nursing school is using voiceover PowerPoints as a pre lecture teaching tool.  Since I have an hour and 15 minute drive each way, I like to listen to the the audio portion and to the lectures I recorded while traveling.  Trying to maximize my drive time.  One of my classmates taught me how to separate the audio files when the computer instructors said it was impossible.  Unfortunately, one of my instructors had her recording volume down low and even with the volume turned all the way up, you can barely hear her.  Is there anyway to adjust this?

TIA,
Marty