Challenge #4 is intended to be a fun one: get the Roomba to play a tune. Four suggestions are given.
There are many sources of information about this problem on the Internet. Apple Mac users may have a slightly easier time, however ultimately you need to send a sequence of notes to the Roomba for it to play automatically. This can be done from MAC, Windows or Linux.
It may indeed be possible to write a direct interface (i.e. a program) that takes a MIDI file and "pipes" it directly to the Roomba. For example: [http://www.midisite.co.uk/midi_search/star_wars_imperial_march.html] has about 20 versions of the Star Wars Imperial March. The Roomba's MIDI palette is more limited than a musical keyboard, hence you may need to remove or truncate notes outside of the Roomba's audio range.
More info at: