METHOD AND APPARATUS FOR RETRIEVING AUDIO INFORMATION USING PRIMARY AND SUPPLEMENTAL INDEXES

An audio retrieval system and method are provided for augmenting the transcription of an audio file with one or more alternate word or phrase choices, such as next-best guesses for each word or phrase, in addition to the best word sequence identified by the transcription process. The audio retrieval system can utilize a primary index file containing the best identified words and/or phrases for each portion of the input audio stream and a supplemental index file containing alternative choices for each word or phrase in the transcript. The present invention allows words that are incorrectly transcribed during speech recognition to be identified in response to a textual query by searching the supplemental index files. During an indexing process, the list of alternative word or phrase choices provided by the speech recognition system are collected to produce a set of supplemental index files. During a retrieval process, the user-specified textual query is matched against the primary and supplemental indexes derived from the transcribed audio to identify relevant documents. An objective ranking function scales matches found in the supplemental index file(s) using a predefined scaling factor, or a value reflecting the confidence value of the corresponding alternative choice as identified by the speech recognition system.