1. A computer-implemented method for performing speech recognition, comprising: selecting, via at least one computer processor configured to execute specific instructions, a first set of word candidates from a plurality of word tokens, wherein the plurality of word tokens are associated with a language model and a word network of a hierarchy of networks; selecting, via the at least one computer processor, a first set of speech unit candidates from a plurality of speech unit tokens, wherein the plurality of speech unit tokens are associated with a speech unit model and a speech unit network of the hierarchy of networks, wherein a word token of the plurality of word tokens corresponds to one or more speech tokens of the plurality of speech tokens; receiving, via the at least one computer processor, audio input, wherein the audio input was captured via a microphone; selecting, via the at least one computer processor, a second set of speech unit candidates from the plurality of speech unit tokens using the audio input and the first set of speech unit candidates; recognizing, via the at least one computer processor, a word candidate in the first set of word candidates based at least partly on a correspondence of the word candidate to one or more speech unit candidates of the second set of speech unit candidates; and selecting, via the at least one computer processor, a second set of word candidates from the plurality of word tokens based at least partly on recognition of the word candidate.