6. A system comprising: one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: receiving, by a speech processing system that includes (i) an automated speech recognizer, (ii) a sensitive information identifier that is associated with a plurality of classifiers that are each associated with a different type of sensitive data, (iii) an acoustic model training engine, (iv) a sensitive information manager, and (v) a logger, audio data corresponding to an utterance that was spoken by a user of a client device and that is to be transcribed by the automated speech recognizer; determining, by the sensitive information identifier of the speech processing system, that at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer is likely a particular type of sensitive data, wherein sensitive data is data that is otherwise to be deleted by the sensitive information manager of the speech processing system without being stored by the logger of the speech processing system in a log of audio data that is received from client devices, or that is otherwise to be deleted from the log of audio data within a predetermined period of time of receipt by the speech processing system, comprising providing the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer to the plurality of classifiers that are associated with the sensitive information manager and that are each associated with a different type of sensitive data, and receiving an indication from a particular classifier associated with the particular type of sensitive data that the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer is indicated as associated with the particular type of sensitive data, above a confidence threshold; before the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer and that is determined to likely be the particular type of sensitive data that is otherwise to be deleted is deleted by the sensitive information manager, providing, by the sensitive information identifier of the speech processing system, the at least a portion of the received audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer and that is determined to likely be the particular type of sensitive data to the acoustic model training engine that trains acoustic models for the automated speech recognizer instead of first deleting the at least the portion of the received audio data; after the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer and that is determined to likely be the particular type of sensitive data is provided to the acoustic model training engine, deleting, by the sensitive information manager of the speech processing system, the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer from a log of audio data, or preventing, by the speech processing system, the at least a portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer from the log of audio data from being stored by the logger of the speech processing system in the log of audio data; receiving, by the automated speech recognizer of the speech processing system and from the acoustic model training engine of the speech processing system, an updated acoustic model that has been trained using the at least the portion of the audio data corresponding to the utterance that is to be transcribed by the automated speech recognizer and that was deleted from, or prevented from being stored in, the log of audio data; and using, by the automated speech recognizer of the speech processing system, the updated acoustic model to recognize subsequently received audio data.
10. The system of claim 6 , wherein sensitive data comprises one or more of contact information, background audio data, personally identifying information, predetermined transcription keywords, and geographic coordinates.