1. A method comprising: determining, at a server, estimated popularity scores for programs identified in an electronic program guide for a time interval, wherein the programs identified in the electronic program guide for the time interval include programs being aired, and wherein one or more of the estimated popularity scores are based at least in part on viewing trends of the programs being aired; and determining, at the server, a voice search vocabulary based on the estimated popularity scores, wherein the voice search vocabulary includes one or more keywords for a keyword search of the electronic program guide during the time interval based on a received voice search request.