1. A method comprising, using a processor: receiving text data converted from speech data, wherein the text data is a word lattice transcribing up to a predetermined multiple number of different possible words for each spoken word interval of the speech data; receiving a single initial search entry comprising one or more phonemes translated from speech data; in a first search, searching for the initial search entry in a first data structure, the first data structure comprising two or more entries, each entry comprising one or more phonemes, measuring an edit distance between the phonemes of the initial search entry and phonemes of each of a plurality of entries in the first data structure, and selecting by a processor a predetermined multiple number of similar entries from the first data structure that have the smallest edit distances; in a second search, using the predetermined multiple number of similar entries from the first data structure output by the first search as one or more inputs for the second search, and searching in the second search the word lattice for the predetermined multiple number of selected similar entries from the first search; and after the second search, displaying, as a search result, a plurality of possible words transcribed for a spoken word interval of the speech data which are found to match in the word lattice.