The free application MP3Gain can be used to increase the volume of your audio files. You don't need to do anything else to get the best results: simply install the application, select the file you want to increase the volume of and start using it.

How can I use MP3Gain?

There are two ways to use MP3Gain:

The first way is to install the application and start using it. You will see a small icon in the notification center of your phone. If you click on this icon, you will see a new menu on the side of your screen. There are two options in this menu: "Increase volume" and "Use as ringtone". If you choose the first option, you will see a small icon in the notification center of your phone.