To expand a bit more on Robert's explanation, once you press the blue button and the sentence or phrase is spoken by Mauricio or Amy or whomever, a graph is created. When you speak the phrase a graph of your voice is created. You are supposed to be able to see how well you spoke the phrase by comparing the graphs. This is of dubious value to me, but if nothing else it is a reminder to repeat each phrase audibly. I think this is a very important part of learning the language, along with reading and hearing the phrases, and most importantly to me, writing each one down longhand while saying and thinking about each word.