The best alternatives to Rock the Note are Voloco App, Voix, and HillaryDonald Go. If these 3 options don't work for you, we've listed a few more alternatives below.
Voloco is a real-time voice-processing app that combines automatic tuning, harmony, and vocoding. Pick a track from your music collection or Voloco's free beat library to sing or rap over, and it will guess the key of the track and tune your voice to that key.
Voix is an app that transforms the sound of your voice using the same professional grade technology that real music producers use in the studio. Just choose one of dozens of "audio filters", hit record, and sing!
Guitar Notebook is an app for iPhone and iPad that helps keep all your notation, audio, and text together in one place, so you can save new song ideas, document DAW tracks, or review songs for rehearsal.