Multimodal concept and word learning using phoneme sequences with errors

In this study, we propose a method for concept formation and word acquisition for robots. The proposed method is based on multimodal latent Dirichlet allocation (MLDA) and the nested Pitman-Yor language model (NPYLM). A robot obtains haptic, visual, and auditory information by grasping, observing, and shaking an object. At the same time, a user teaches object features to the robot through speech, which is recognized using only acoustic models and transformed into phoneme sequences. As the robot is supposed to have no language model in advance, the recognized phoneme sequences include many phoneme recognition errors. Moreover, the recognized phoneme sequences with errors are segmented into words in an unsupervised manner; however, not all words are necessarily segmented correctly. The words including these errors have a negative effect on the learning of word meanings. To overcome this problem, we propose a method to improve unsupervised word segmentation and to reduce phoneme recognition errors by using multimodal object concepts. In the proposed method, object concepts are used to enhance the accuracy of word segmentation, reduce phoneme recognition errors, and correct words so as to improve the categorization accuracy. We experimentally demonstrate that the proposed method can improve the accuracy of word segmentation and reduce the phoneme recognition error and that the obtained words enhance the categorization accuracy.