7. The computer-implemented method of claim 6 , further comprising: processing a plurality of training audio data samples to determine a plurality of feature vectors, wherein each feature vector includes a value for each of a second plurality of feature dimensions and wherein the first plurality of feature dimensions is a subset of the second plurality of feature dimensions and the second plurality of feature dimensions includes the first feature dimension; determining a threshold utility; determining the first utility metric is above the threshold utility; and including the first feature dimension in the first plurality of feature dimensions.
6. The computer-implemented method of claim 5 , further comprising: determining a first value of a first feature dimension, the first value associated with first audio data including a first keyword; determining a second value of the first feature dimension, the second value associated with second audio data not including a keyword; and determining a first utility metric for the first feature dimension using the first value and the second value.