4. The method of claim 1 , comprising: receiving metadata that corresponds to the speech, wherein classifying the speech into the at least one voice cluster based on the identified acoustic features of the speech comprises classifying the speech into the at least one voice cluster based on the identified acoustic features of the speech and the metadata that corresponds to the speech.
4. The method of claim 1 , comprising: receiving metadata that corresponds to the speech, wherein classifying the speech into the at least one voice cluster based on the identified acoustic features of the speech comprises classifying the speech into the at least one voice cluster based on the identified acoustic features of the speech and the metadata that corresponds to the speech. 8. The method of claim 4 , wherein the metadata comprises a location of a mobile device that captured the speech, wherein the location of the mobile device comprises a location of a moving vehicle.