1. A method comprising: sending voice input data received by a media device to a speech-to-text service; receiving, by the media device from the speech-to-text service, a textual representation of at least a portion of the voice input data; generating a signature based on at least a portion of the textual representation, wherein the signature is a hash value; locating a particular data entry among a set of data entries by searching the set of data entries for a data entry matching the signature generated based on the at least a portion of the textual representation, each data entry of the set of data entries specifying a mapping between a given signature and one or more media device actions; updating the set of data entries by storing the mapping between the signature and the at least a portion of the textual representation; in response to locating a particular data entry among the set of data entries based on the generated signature, performing one or more particular media device actions associated with the particular data entry, the one or more particular media device actions including sending a media content query to a media search service; receiving, by the media device, one or more content item listings based on the media content query; and generating for display at least a portion of the one or more content item listings.