There are a number of ear training apps available for the iPhone, but InTune has actual science to back it up [PDF Abstract].
Produced by Wittenberg University, InTune makes a game out of picking out intonation, complete with Game Center integration for leader board scores. Professor Dan Kazez sent me a promo-code and a limerick to get me to try it out and I'm glad he did! The game starts off by playing a tone, followed by a second tone. You have to pick whether the new tone is a higher or lower pitch than the first. This starts off as easy as it sounds, but as you progress the gap between these two tones continues to diminish. You gain and lose score based on how accurate you are, but screw it up 3 times and it is game over.
The idea here is that as you try to "win" at the game you're training your ear and brain to listen to these slight variations in tone. I mean really slight. This isn't a difference of full notes, but rather percents of a step. On my first play through my brain was baffled by the time I got to about 30% of a half-step, playing on the hardest difficulty setting; Change Mode. I saw immediate gains though, and on my 5th play-through I didn't get that brain-ear disconnect until about 10%. It's hard to explain, but there was a real feeling behind this discontinuity. I knew when I hit that wall at 30%, and then I knew I was soaring past it by my 5th game. These results may not be typical, I am a synthesist and spend a lot of time listening to slight tonal shifts. The abstract suggests everyone should see improvement over the course of a week and progressively better from there.
InTune iTunes Description:
It’s easy to find apps to help musicians play in tune, but not to improve a musician’s ears. Now that changes, with InTune, the app that helps musicians play in tune by improving their ability to hear. Use one of four game modes (starting on different pitches). Compete with your friends via Game Center. And you can share your score via email, Twitter, or Facebook.
InTune is an outgrowth of twenty-five years of research and testing in the field of intonation by cellist and professor of music Daniel Kazez. The concept began as a simple game to test the ability to hear two pitches that are very close together. But then in a university research study, Kazez discovered that students’ hearing improved the more often they played — at triple the rate of those who did not.
With InTune, you’ll hear two pitches and determine whether the second is higher or lower than the first. It starts easy and then gets more difficult, until you reach the closest pair of pitches that you can distinguish. Play InTune again to improve your score — and your ear! Share your score with others and find out who has the best ear.