Wouldn't it be a good idea to make an app which writes music for you. You press a button and hum a tune then it works out what musical notes you are making and how long you are holding them for and then it writes music for you and it can play the music back for you on piano or guitar or whatever musical instrument you want. Then if you want to add chords you can select the musical note you want to add a chord to and hum the chord. The app name 'Hum Music?' 'Humusic?'