6. A computer-implemented method, comprising: under control of one or more computing devices configured with specific computer-executable instructions, receiving an identification of a desired training utterance having a first portion and a second portion, wherein the desired training utterance is not included in a corpus; selecting, from the corpus, a first utterance comprising at least a first portion of the desired training utterance; extracting, from the first utterance, a portion of the first utterance comprising the first portion of the desired training utterance, wherein the first portion of the desired training utterance and at least the portion of the first utterance are associated with a first desired characteristic; selecting, from the corpus, a second utterance comprising at least a second portion of the desired training utterance; extracting, from the second utterance, a portion of the second utterance comprising the second portion of the desired training utterance, wherein the second portion of the desired training utterance and at least the portion of the second utterance are associated with a second desired characteristic; concatenating at least the portion of the first utterance and the portion of the second utterance to generate the desired training utterance; and training an acoustic model using the desired training utterance that is generated.
6. A computer-implemented method, comprising: under control of one or more computing devices configured with specific computer-executable instructions, receiving an identification of a desired training utterance having a first portion and a second portion, wherein the desired training utterance is not included in a corpus; selecting, from the corpus, a first utterance comprising at least a first portion of the desired training utterance; extracting, from the first utterance, a portion of the first utterance comprising the first portion of the desired training utterance, wherein the first portion of the desired training utterance and at least the portion of the first utterance are associated with a first desired characteristic; selecting, from the corpus, a second utterance comprising at least a second portion of the desired training utterance; extracting, from the second utterance, a portion of the second utterance comprising the second portion of the desired training utterance, wherein the second portion of the desired training utterance and at least the portion of the second utterance are associated with a second desired characteristic; concatenating at least the portion of the first utterance and the portion of the second utterance to generate the desired training utterance; and training an acoustic model using the desired training utterance that is generated. 9. The computer-implemented method of claim 6 , wherein training the acoustic model using the desired training utterance that is generated comprises creating a new acoustic model or adapting an existing acoustic model.