3. A computer-implemented method comprising: under control of one or more computing devices configured with specific computer-executable instructions, generating first speech recognition results using a first portion of a plurality of sequential portions of audio data, wherein the audio data represents a user utterance, and wherein the first speech recognition results are generated without using any sequential portion, of the plurality of sequential portions of audio data, following the first portion; generating a first semantic representation of the user utterance using the first speech recognition results and without using speech recognition results representing a second portion, of the plurality of sequential portions of audio data, following the first portion; determining a first score indicating a degree of confidence in the first semantic representation; determining that the first score satisfies a first threshold; in response to determining that the first score satisfies the first threshold: identifying a content item being requested by the user utterance; and loading a data file representing the content item; generating second speech recognition results using the first portion and the second portion of the plurality of sequential portions of audio data; generating a second semantic representation of the user utterance using the second speech recognition results; determining a second score indicating a degree to which the second semantic representation is the same as the first semantic representation; determining that the second score satisfies a second threshold; and in response to determining that the second score satisfies the second threshold, initiating presentation of the content item using the data file.
3. A computer-implemented method comprising: under control of one or more computing devices configured with specific computer-executable instructions, generating first speech recognition results using a first portion of a plurality of sequential portions of audio data, wherein the audio data represents a user utterance, and wherein the first speech recognition results are generated without using any sequential portion, of the plurality of sequential portions of audio data, following the first portion; generating a first semantic representation of the user utterance using the first speech recognition results and without using speech recognition results representing a second portion, of the plurality of sequential portions of audio data, following the first portion; determining a first score indicating a degree of confidence in the first semantic representation; determining that the first score satisfies a first threshold; in response to determining that the first score satisfies the first threshold: identifying a content item being requested by the user utterance; and loading a data file representing the content item; generating second speech recognition results using the first portion and the second portion of the plurality of sequential portions of audio data; generating a second semantic representation of the user utterance using the second speech recognition results; determining a second score indicating a degree to which the second semantic representation is the same as the first semantic representation; determining that the second score satisfies a second threshold; and in response to determining that the second score satisfies the second threshold, initiating presentation of the content item using the data file. 7. The computer-implemented method of claim 3 , wherein generating the first semantic representation comprises determining a user intent.