Methods and systems are provided for finding a target document in spoken language processing. One of the methods includes calculating a score of each document in a document set, in response to a receipt of first n words of output of an automatic speech recognition (ASR) system, n being equal or greater than zero. The method further includes reading a prior distribution of each document in the document set from a memory device, and updating, for each document in the document set, the score, using the prior distribution, and a weight for interpolation, the weight for interpolation being set based on a confidence score of output of the ASR system. The method additionally includes finding a target document among the document set, based on the updated score of each document.