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