Intelligent Gadgets
What Key
What Key determines the key of a song in real time. Combining the spectrum analyzer from Pitch to Note with music theory algorithms, What Key matches the notes being played to major, minor, blues, and bebop (jazz) scales in all keys, picking the scale and key with the best match.

Click here for a demo showing the capabilities of an earlier version What Key? . The functionality of the current version (which performs significantly better than the previous one) is described below.


Two screens are provided: one shows the histogram of notes over an interval of time, with the best matching scale given (left), the other is a probability distribution, with the most probable key given (right). Touching the "Notes/Key" button (top right) switches between the two views. The period of time over which the analysis is performed is controlled by the bottom right button, which switches from a longer period of time for more slowly varying harmonic changes to a shorter period of time for quick changes and modulations. The middle button selects the pitch range, and the left button chooses from major/minor, blues, or jazz scales.

While many songs can be described well by minor/minor scales, others like blues and jazz often use altered tones. For example, the notes: C, D, E, Eb, G, and A form a blues scale in the key of C. Common bebop scales in C are the major (C, D, E, F, G, Ab, A, B) and dominant (C, D, E, F, G, A, Bb, B). Try switching between different scales for the best result (a well defined peak in the key display indicates a valid reading). Note the screenshots (left and right) are from different songs.

Contact us if you want additional scales to be included in future releases of the app.

For more information contact: intelligentGadgets@comcast.net