Any audio recording software will do. Recording the dialog for the animatic is very simple so no special audio program is needed.
You can use Audacity (Linux, Windows or Macintosh) which is free.
You can use Sound Forge on Windows.
You can use GarageBand or iMovie on the Macintosh.
etc.
Professional audio software
Later when doing ADR and live recording of musicians in sync with your movie, you will need special recording software which will play a movie clip at the same time it is recording audio. But for now, iMovie is good enough since it plays a movie while your record your music.
The cheapest alternative - Audacity - FREE
If you do not have a professional audio program, you can download Audacity which is free. It will work on most computers. Click here to learn more about Audacity.
The Next Page
Continue this lesson on the computer hardware needed for recording the dialog for the animatic.