Spira is a radically new musical keyboard that supports multitouch. It looks difficult to play at first sight, but actually it is very intuitive and easy. In the main screen, you can see a spiral line and twelve radial lines. You can get different tones from the cross points where spiral and radial lines meet. The best way to understand the concept of Spira is just to touch it and have fun!

On Spira's keyboard, tones are aligned in chromatic order along the spiral line, and in octave order along the radial lines. If you touch along the spiral line, you will get the chromatic scale. If you touch from the origin and move to a specific direction along a radial line, you will get a tone, then double tone of it, then double tone of that, and so on.

There are many benefits with this alignment. For example, you can always get a specific note on a specific angular direction. As a result, changing the chord's voicing has become easier than ever. In addition, you can learn the musical structure efficiently because Spira treats every semitones as equal.

Although Spira is tuned as equally-tempered scale, you can also play every tuning in "Fretless" mode. Swipe the control panel at the top of the screen, and you can see the "Fretless" button. Tap it to start fretless mode. In fretless mode, you can get any tones between the semitones. It means that you can easily do the vibrato. Besides, you can also access a wide range of frequencies by using the transpose buttons next to the "Fretless" button.

If you want to change sounds, double tap the sound button. Spira supports simple FM sound source. FM stands for frequency modulation. It has two pure sine wave generators. One is called carrier and the other is called modulator. Modulator modulates carrier's phase by its own value. In math equation, it looks like this.