We’ve been impressed by the new breed of music-teaching apps that use the iPhone or iPad microphone to listen to what a user is playing, and thus provide feedback. Ovelin’s WildChords has been the highest-profile so far, but it faces competition from a new iPhone app called Strumify. Released on the App Store this morning, it supports guitar, ukulele and mandolin. “The powerful real-time listening engine, easy-to-read graphics, and multi-touch interface create a highly-interactive experience. Strumify makes practicing and learning to play fun,” claims its App Store listing. It teaches chords and progressions, with in-app purchases used to buy songs and exercises. Songs can also be imported using the PowerTab and chopro formats. It’s definitely one to watch.