It can be unsafe listening to music while you walk or ride through the city, but the ‘Awareness! The Headphone App’ begins to solve this problem by acting as your urban ears while you’re hooked up to your iPod.
Using the internal microphone on your Apple MP3 player, the ‘Awareness! The Headphone App’ has an integrated meter to judge innocuous sounds from notable noise. Background noise levels are calibrated by the user and the app alerts you if it hears trouble approaching.