16. A method for defining a subset of a library used for processing voice inputs, comprising: at an electronic device with one or more processors and memory storing one or more programs for execution by the one or more processors: providing a library of words from which to process voice inputs; identifying user interest information by identifying words or phrases from previously received voice inputs that were determined to be properly identified; extracting, from the user interest information, words that the user is likely to use to provide a voice input; and defining a subset of the library, wherein the subset comprises at least the words of the library matching the extracted words.
23. The method of claim 16 , wherein the subset of library words includes words associated with an application that is used by the user more than a threshold amount.