16. The search system as claimed in claim 14 , wherein the merging of the lists uses a Threshold Algorithm to scan results from different indices for a same document to aggregate document scores for the same document.
14. A search system for spoken document retrieval using multiple search transcription indices, the system comprising: a processor; a memory containing instructions that, when executed by the processor, adapt the search system to: receive a search query formed of one or more query terms, determine a first type and a second type of query term by reference to a speech recognition vocabulary, wherein the first type includes a term in a speech recognition vocabulary and the second type includes a term not in the speech recognition vocabulary, identify multiple search transcription indices for searching a first query term based on the type of the first query term, wherein the multiple indices include a first phonetic index and a second index that is different from the first index, rank results from the second index based on temporal proximity of phones, wherein the ranking computes a score in accordance with the following expression: score ⁡ ( k , t 0 k , D ) = 1 - ∑ i = 1 l ⁢ 5 ⁢ ( t i k - ( t i - 1 k + d i - 1 k ) ) l where k denotes a keyword having phonemes that may occur in a document transcript D at times t i k and having durations d i k ; receive lists of documents from searching the multiple search transcription indices, for the first query term and for a first document, merge the received lists by evaluating timestamps of words and subwords in the first document to determine whether the words and subwords are in a correct order and a difference in time between adjacent words and subwords is within a threshold value, wherein the words and subwords in the first document correspond to the input phrase, and output search results to a user based in part on the merge of the received lists by evaluating timestamps of words and subwords in the first document.