1. A system comprising: a computer-readable memory storing executable instructions; and one or more processors in communication with the computer-readable memory, wherein the one or more processors are programmed by the executable instructions to at least: obtain a sequence of feature vectors, wherein the sequence of feature vectors represents at least a portion of a stream of audio data; generate a keyword score based at least partly on a likelihood that a particular feature vector of the sequence of feature vectors represents audio data corresponding to a keyword; generate a background score based at least partly on a likelihood that the particular feature vector represents audio data corresponding to background audio; determine that a difference between the keyword score and the background score is greater than differences associated with feature vectors preceding the particular feature vector in a subset of the sequence of feature vectors, wherein the particular feature vector is in a center of the subset; determine that the difference is greater than differences associated with feature vectors subsequent to the particular feature vector in the subset; and generate data indicating the particular feature vector corresponds to an end of the keyword.
2. The system of claim 1 , wherein the one or more processors are further programmed by the executable instructions to determine that the particular feature vector corresponds to the end of the keyword based at least partly on the difference being greater than a threshold.