Open Access

Dynamic Bayesian Networks for Audio-Visual Speech Recognition

  • Ara V. Nefian1Email author,
  • Luhong Liang2,
  • Xiaobo Pi2,
  • Xiaoxing Liu2 and
  • Kevin Murphy3
EURASIP Journal on Advances in Signal Processing20022002:783042

Received: 30 November 2001

Published: 28 November 2002


The use of visual features in audio-visual speech recognition (AVSR) is justified by both the speech generation mechanism, which is essentially bimodal in audio and visual representation, and by the need for features that are invariant to acoustic noise perturbation. As a result, current AVSR systems demonstrate significant accuracy improvements in environments affected by acoustic noise. In this paper, we describe the use of two statistical models for audio-visual integration, the coupled HMM (CHMM) and the factorial HMM (FHMM), and compare the performance of these models with the existing models used in speaker dependent audio-visual isolated word recognition. The statistical properties of both the CHMM and FHMM allow to model the state asynchrony of the audio and visual observation sequences while preserving their natural correlation over time. In our experiments, the CHMM performs best overall, outperforming all the existing models and the FHMM.


audio-visual speech recognitionhidden Markov modelscoupled hidden Markov modelsfactorial hidden Markov modelsdynamic Bayesian networks

Authors’ Affiliations

Intel Corporation, Microprocessor Research Labs, Santa Clara, USA
Intel Corporation, Microcomputer Research Labs, Chaoyang District, China
Computer Science Division, University of California, Berkeley, Berkeley, USA


© Nefian et al. 2002