From iApp Universe:
"Volume Up - sound booster" provides a linear volume control to let you control the volume of your iPod music in a more subtle way. Linear volume control offers more than 16 increments defaulted so you can adjust the volume level to a degree your ears are more comfortable with. Slide the slider up and down to adjust the volume. Add songs and control your music play right in the app. You can also user the recorder to record any sound and play it back with the volume control.