1. A method for speech recognition, the method comprising: extracting, by one or more data processors, audio characteristics from acquired voice signals; identifying, by the one or more data processors, a syllable confusion network based on at least information associated with the audio characteristics; generating, by the one or more data processors, a word lattice based on at least information associated with the syllable confusion network and a predetermined phonetic dictionary; and calculating, by the one or more data processors, an optimal character sequence in the word lattice as a speech recognition result of the acquired voice signals; wherein the syllable confusion network includes one or more sorted slices, wherein each of the one or more sorted slices includes a set of syllables, and wherein each syllable in the set of syllables is associated with a score; and wherein the generating a word lattice based on at least information associated with the syllable confusion network and a predetermined phonetic dictionary includes: traversing candidate characters in the predetermined phonetic dictionary corresponding to the slices in the syllable confusion network; in response to a first candidate character corresponding to a first syllable in a current slice and a second candidate character corresponding to a second syllable in a next slice forming a word, generating a first lattice node based on at least information associated with the word; and determining a first node score for the first lattice node based on a first score corresponding to the first syllable in the current slice and a second score corresponding to the second syllable in the next slice; in response to the first candidate character corresponding to the first syllable in the current slice and the second candidate character corresponding to the second syllable in the next slice not forming a word, generating a second lattice node based on at least information associated with the first candidate character; and determining a second node score for the second lattice node based on the first score.