9. The system of claim 8 , wherein identifying the concepts from audio features of the audio stream comprises: separating the audio stream into a first substream that comprises the user speech data and a second substream that comprises background audio; and using a combination of at least the first substream and the second substream to recognize the concepts.
9. The system of claim 8 , wherein identifying the concepts from audio features of the audio stream comprises: separating the audio stream into a first substream that comprises the user speech data and a second substream that comprises background audio; and using a combination of at least the first substream and the second substream to recognize the concepts. 10. The system of claim 9 , wherein identifying the concepts from audio features of the audio stream comprises: comparing audio features of the second substream to audio features of known audio segments; determining that the audio features of the second substream correspond to audio features of a particular known audio segment; and identifying one or more concepts that are identified as being related to the particular known audio segment.