Multi-stream parameterization for structural speech recognition

Recently, a novel and structural representation of speech was proposed [1, 2], where the inevitable acoustic variations caused by nonlinguistic factors are effectively removed from speech. This structural representation captures only microphone- and speaker-invariant speech contrasts or dynamics and uses no absolute or static acoustic properties directly such as spectrums. In our previous study, the new representation was applied to recognizing a sequence of isolated vowels [3]. The structural models trained with a single speaker outperformed the conventional HMMs trained with more than four thousand speakers even in the case of noisy speech. We also applied the new models to recognizing utterances of connected vowels [4]. In the current paper, a multiple stream structuralization method is proposed to improve the performance of the structural recognition framework. The proposed method only with 8 training speakers shows the very comparable performance to that of the conventional 4,130-speaker triphone-based HMMs.