If you studied Western music theory at some point, you’re probably familiar with the circle of fifths. Without getting too far into it, the circle of fifths is a way of organizing pitches to show their relationship with each other. Comprehending it helps with playing scales and chords, remembering the number of sharps and flats in various keys, and so on. Circle Theory for iOS, a straightforward iPhone app, brings the circle of fifths to the iPhone, offering musicians a much-needed handy reference. Circle Theory’s interface is boringly straightforward. This is as it should be, because too much clutter would confuse the whole point of the circle of fifths: to include almost all the relevant information to Western harmony in one simple chart. Tapping keys on the chart displays different information about that key. Users can view key signatures in major and minor scales on multiple clefs and pitches for all the major modes; build triads; and, with transposition assistant, use select a new starting key on the inner ring. All of these features are easy to use, whether or not you’ve seen them in chart form before, and deliver information with which all serious musicians should be familiar. The circle of fifths (which also works in reverse, as the circle of fourths) is the Rosetta Stone for decoding Western music theory, and has been used by educators for years to simplify the understanding of keys, chord and scale relationships. This app packages the chart in a simple straightforward tool, which composers and musicians who make use of music theory can use every day. Features Interactive circle of fifths chart Selectable Clef, Sharps/Flats, Scale, Mode, Triad, and Transposition You can use it on an iPad with VGA cable to project the chart as a classroom aid. Compatible with iPhone, iPod Touch, and iPad (iOS 4.2 or later), Circle of Fifths is available in the iTunes app store for $5. -Connor McKnight

Circle Theory is a Circle Of Fifths (sometimes known as a Circle Of Fourths). The Circle Of Fifths is a tool for musicians to assist them in seeing the relationship between notes, provide key signatures for both major and minor scales, assists in transposing between keys, and it also has a helpful guide to figure out note intervals per musical mode. An iPad VGA adapter can be used to view the circle on an external screen or projector. Shortcuts: • Tap or drag on the outer ring to change the tonic note / key signature • Double-tap the outer ring to cycle through the inner ring displays • Double-tap the center of the circle to cycle through the clefs • When the inner ring is displaying a musical mode, drag the inner ring to select a new mode • When the inner ring is displaying the transposition assistant, drag the inner ring to select a new starting key / note"