This paper presents a two-stage approach to story segmentation and topic classification of broadcast news. The two-stage paradigm adopts a decision tree and a maximum entropy model to identify the potential story boundaries in the broadcast news within a sliding window. The problem for story segmentation is thus transformed to the determination of a boundary position sequence from the potential boundary regions. A genetic algorithm is then applied to determine the chromosome, which corresponds to the final boundary position sequence. A topic-based segmental model is proposed to define the fitness function applied in the genetic algorithm. The syllable- and word-based story segmentation schemes are adopted to evaluate the proposed approach. Experimental results indicate that a miss probability of 0.1587 and a false alarm probability of 0.0859 are achieved for story segmentation on the collected broadcast news corpus. On the TDT-3 Mandarin audio corpus, a miss probability of 0.1232 and a false alarm probability of 0.1298 are achieved. Moreover, an outside classification accuracy of 74.55% is obtained for topic classification on the collected broadcast news, while an inside classification accuracy of 88.82% is achieved on the TDT-2 Mandarin audio corpus.

This study presents a novel approach to unsupervised pronunciation grammar growing for non-native speech recognition. Unsupervised pronunciation grammar growing includes pronunciation variation graph construction and non-native grammar generation. Knowledge-based and data-driven approaches are considered for variation graph construction. The measurement of confidence and support is used for grammar selection. Experiments show that unsupervised pronunciation grammar growing is suitable for the improvement of non-native speech recognition.

This correspondence presents a speech sentence compression scheme. A compressed word sequence is first extracted. Speech segments, in the spoken document, corresponding to the extracted words are selected for concatenation. Evaluation of the proposed approach shows the compressed speech sentence retains important and meaningful information and naturalness

This study presents an approach for segmenting and classifying an audio stream based on audio type. First, a silence deletion procedure is employed to remove silence segments in the audio stream. A minimum description length (MDL)-based Gaussian model is then proposed to statistically characterize the audio features. Audio segmentation segments the audio stream into a sequence of homogeneous subsegments using the MDL-based Gaussian model. A hierarchical threshold-based classifier is then used to classify each subsegment into different audio types. Finally, a heuristic method is adopted to smooth the subsegment sequence and provide the final segmentation and classification results. Experimental results indicate that for TDT-3 news broadcast, a missed detection rate (MDR) of 0.1 and a false alarm rate (FAR) of 0.14 were achieved for audio segmentation. Given the same MDR and FAR values, segment-based audio classification achieved a better classification accuracy of 88% compared to a clip-based approach.

This paper presents a spoken document summarization scheme using acoustic, prosodic, and semantic information. First, speech recognition confidence is estimated to choose reliable words from the speech transcription. Prosodic information, including pitch and energy, is used for stressed word selection. Latent semantic indexing (LSI) is adopted to identify significant words. Finally, word trigram and semantic dependency is measured to include the syntactic and semantic information for speech summarization. The dynamic programming (DP) algorithm is used to find the best summarization result according to the summarization score estimated from the above five measures. Finally, the summarized result is presented by the concatenation of the summarized speech words. Experimental results indicate that the proposed approach effectively extracts important words and gives a promising speech summary.