1. A method for building a language model, adapted to an electronic apparatus, the method comprising: obtaining a text corpus through training with a plurality of speech signals based on different languages, dialects or different pronunciation habits; receiving a plurality of candidate sentences; and obtaining a plurality of phonetic spellings matching each of words in each of the candidate sentences and a plurality of word probabilities by training with the text corpus, so as to obtain a candidate sentence table corresponding to the candidate sentences, wherein the step of obtaining the text corpus through training with the speech signals based on different languages, dialects or different pronunciation habits comprises: receiving the phonetic spellings matching pronunciations of each of the words according to the corresponding words in the speech signals; and obtaining the word probabilities of each of the words corresponding to each of the phonetic spellings in the text corpus by training according to each of the words and the phonetic spellings.