1. A method for improving voice recognition accuracy when a user submits a search query by voice to search a domain of items, the method comprising: prompting a user to submit a set of characters of a voice query for searching the domain of items, and receiving the set of characters from the user, wherein the voice query is an utterance by the user of a search query, and the set of characters defines a portion of the search query; in response to receiving the set of characters from the user, identifying a subset of items in the domain that correspond to the set of characters; generating a dynamic grammar based at least in part on the subset of items, said grammar specifying valid utterances for interpreting the voice query; prompting the user to submit the voice query, and receiving the voice query from the user; and interpreting the voice query using the dynamic grammar.