1. A computer-implemented method comprising: receiving a plurality of audio frame vectors that each model an audio waveform during a different period of time; generating an output feature vector for each of the audio frame vectors, wherein each output feature vector includes a set of scores that characterize an acoustic match between the corresponding audio frame vector and a set of expected event vectors, each of the expected event vectors corresponding to one of the scores and defining acoustic properties of at least a portion of a keyword; and providing each of the output feature vectors to a posterior handling module.