Play It Down App for iOS
"Play It Down is like three fun music and audio apps in one!
Auto-Old My Music
Pick a song from your library, use the Auto-Old slider to “age” your ears, and hear what your music sounds like to someone 5, 10, 20, even 30 years older than you!
The Ear Knob
Are your ears older than you are? Put your ears to The Ear Knob age test, and compare with friends to see who can hear the highest frequencies.
The Volume Zone
What’s louder, a live rock concert or an album on your iPod? Use this simple decibel meter to measure sound volume anywhere, anytime. Even measure the volume of your earbuds."
This is a free app.