9. A non-transitory computer storage medium storing instructions that, when executed by data processing apparatus, cause the one or more computers to perform operations comprising: receiving, by an automated speech recognizer (ASR) system that includes (i) a context selector, (ii) a language model biaser, (iii) an ASR, (iv) a particular language model, and (v) a previously biased language model, audio data corresponding to an utterance of a user; determining, by the context selector of the ASR system, that the user is likely no longer within a particular context that is associated the previously biased language model; in response to determining that the user is likely no longer within a particular context that is associated with the previously biased language model, selecting, by the language model biaser of the ASR system, the particular language model for use in transcribing utterances; after selecting the baseline language model, generating, by the ASR of the ASR system, a transcription of the utterance using the particular language model; and providing a representation of the transcription for output.
9. A non-transitory computer storage medium storing instructions that, when executed by data processing apparatus, cause the one or more computers to perform operations comprising: receiving, by an automated speech recognizer (ASR) system that includes (i) a context selector, (ii) a language model biaser, (iii) an ASR, (iv) a particular language model, and (v) a previously biased language model, audio data corresponding to an utterance of a user; determining, by the context selector of the ASR system, that the user is likely no longer within a particular context that is associated the previously biased language model; in response to determining that the user is likely no longer within a particular context that is associated with the previously biased language model, selecting, by the language model biaser of the ASR system, the particular language model for use in transcribing utterances; after selecting the baseline language model, generating, by the ASR of the ASR system, a transcription of the utterance using the particular language model; and providing a representation of the transcription for output. 12. The medium of claim 9 , wherein determining that the user is likely no longer within the particular context comprises determining that the user is likely in a different context.