ToneBoard is a $.99 iphone app, inspired by the Yamaha Tenori On, that features a 10 x 16 tone matrix.
The horizontal line is the time axis while the vertical line is the tone axis. 16 different tones are distributed along the tone axis. Press each square to activate the tone and press again to deactivate it.
Note that version 1 of ToneBoard has a bug that causes it to crash on some iPhones. An update has been submitted to the app store.
If you’ve used ToneBoard, leave a comment with your thoughts.