Developer Batuhan Bozkurt has released Circuli – an ambient sound generator for iOS.

Features:

• Circles grow at a constant rate.
• No two circle can overlap.
• Bigger circle pushes and shrinks smaller circle when in contact.
• A circle ?pops? and makes a sound when its boundary intersects with the center of another circle.
• The pitch of the sound is determined by the position of the circle on the background. Bigger the hole, higher the pitch.
• The envelope of the produced sound is determined by a number of parameters including final circle size and time of interaction between two involved circles.

Circuli is $.99 in the App Store.