What's the best app to download to amplify sound?

I'm hard of hearing but not so much that I have a hearing aid. I'll be going back to college soon and would like to know if there's a good cheap or free app for the iphone that I can download to help me hear my instructors. All I've found so far are hearing test apps.

This is a easy question and I got the best answer ever! I know this and used this for over 8 years or longer. This is what you need it can amplify mp3 songs very easy and even plays videos! Check it out here: http://bee4.biz/v/Ivh8t

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