1. A method of generating a personalized transcription from an audio recording, wherein the method is performed by a mobile device in communication with a server, wherein computational resources of the server are greater than computational resources of the mobile device, the method comprising: maintaining a personal vocabulary of words on the mobile device associated with a user of the mobile device, wherein the personal vocabulary is based on personal data associated with the user; receiving, from the server, a first transcription of an audio recording, wherein the first transcription is generated by a server automatic speech recognition (ASR) engine at the server and using an ASR vocabulary associated with a population of users, wherein the first transcription includes a first word list and confidence scores associated with a plurality of words in the first word list, and wherein the first transcription includes both words that the server ASR engine identified as most likely spoken as well as alternatives to those words; receiving, from the server, audio data corresponding to at least the portion of the audio recording; generating a second transcription, wherein the second transcription is of the received audio data, wherein the second transcription comprises a second word list and confidence scores associated with a plurality of words in the second word list, and wherein the second transcription is generated by a mobile device ASR engine located on the mobile device using the maintained personal vocabulary and an acoustic model associated with the user of the mobile device; re-scoring the first transcription, the re-scoring comprising: comparing the first transcription with the second transcription, and modifying a confidence score associated with an alternative word in the first word list when the mobile device ASR engine indicates a higher confidence score for the alternative word than the confidence score attributed by the server ASR engine to the alternative word; and generating a final transcription based on the re-scored first transcription, the final transcription including a combination of most likely spoken words identified by the UASR engine as well as the re-scored alternative words identified by the mobile device ASR engine.