Open vocabulary spoken document retrieval by subword sequence obtained from speech recognizer

We present a method for open vocabulary retrieval based on a spoken document retrieval (SDR) system using subword models. The present paper proposes a new approach to open vocabulary SDR system using subword models which do not require subword recognition. Instead, subword sequences are obtained from the phone sequence outputted containing an out of vocabulary (OOV) word, a speech recognizer outputs a word sequence whose phone sequence is considered to be similar to the OOV word. When OOV words are provided in a query, the proposed system is able to retrieve the target section by comparing the phone sequences of the query and the word sequence generated by the speech recognizer.