A sruti box or shruti box is a bellows driven harmonium-like instrument that provides a drone, used in Indian music and spiritual practices.
Henry Lowengard’s Sruti Box iPhone application simulates a sruti box with 12 reeds, which can be tuned in various ways, and you pump the bellows by waving the phone. There is a parameter that can be set so you don’t have to do this, but I find it adds to the authenticity in a subtle way.
SrutiBox provides sets of intervals, timbres and voicing controls to build drones for music, meditation, tuning, and educational purposes.
For example, you can use a variety of tuning tables, including Just, Harmonic, equal tempered & Sruti.
Here’s a demo of the Sruti Box in action:
I like that Lowengard is doing something a little left-field with Sruti Box. I downloaded this earlier – not sure exactly what I’m going to do with it, but it’s three bucks in the App Store (App Store link), so it’s cheap to check out.