This clip, recorded from the inside of an acoustic guitar captures the instrument’s strings wildly oscillating in a way that’s different from what you would see if you were watching the videographer strum his six-string live — instead of a subtle vibrating, the strings move in exaggerated waves, like lines on a heart monitor.

The oscillation is not an enhancement added in post-production. It’s a result of the iPhone’s “Rolling Shutter” effect, which films by scanning the frame as opposed to taking a series of snapshots.

Check out the video below, which is really cool no matter how it was done: