If you enjoy moving your hands as if you're conducting a piece of music that you like, then SoundTracer may be right up your alley. The experimental new iOS app allows you to find a song within a digital library, by "drawing" that music in the air with your phone.
SoundTracer was developed at The University of Oslo, by researcher Olivier Lartillot.
To use it, you simply move your iPhone or iPad vertically in the air, in a manner that replicates the rise and fall of the pitch of the introduction to the piece of music in question. The app uses the device's accelerometer and gyroscope to track these gestures, providing ascending and descending audio feedback tones as it does so.
What results is an onscreen graph displaying the range of movement. That graph is compared to others for the intros to known pieces of music within the user's library. If a match is found, that piece is brought up for the user.
In its present form, SoundTracer only works with a collection of about 50 Norwegian folk songs, the graphs of which Lartillot has manually programmed into the app. He has developed automation algorithms, however, which should let future versions of the app generate their own graphs for every piece of music in the user's library.
The technology is demonstrated in the following video.
Source: The University of Oslo