What is Out-of-Vocabulary

This chapter addresses a number of advances in formulating spoken document retrieval for the National Gallery of the Spoken Word (NGSW) and the U.S.-based Collaborative Digitization Program (CDP). After presenting an overview of the audio stream content of the NGSW and CDP audio corpus, an overall system diagram is presented with a discussion of critical tasks associated with effective audio information retrieval that include advanced audio segmentation, speech recognition model adaptation for acoustic background noise and speaker variability, and information retrieval using natural language processing for text query requests that include document and query expansion. Our experimental online system entitled “SpeechFind” is presented which allows for audio retrieval from the NGSW and CDP corpus. Finally, a number of research challenges as well as new directions are discussed in order to address the overall task of robust phrase searching in unrestricted audio corpora.