We describe an audio-visual automatic continuous speech recognition system, which significantly improves speech recognition performance over a wide range of acoustic noise levels, as well as under clean audio conditions. The system utilizes facial animation parameters (FAPs) supported by the MPEG-4 standard for the visual representation of speech. We also describe a robust and automatic algorithm we have developed to extract FAPs from visual data, which does not require hand labeling or extensive training procedures. The principal component analysis (PCA) was performed on the FAPs in order to decrease the dimensionality of the visual feature vectors, and the derived projection weights were used as visual features in the audio-visual automatic speech recognition (ASR) experiments. Both single-stream and multistream hidden Markov models (HMMs) were used to model the ASR system, integrate audio and visual information, and perform a relatively large vocabulary (approximately 1000 words) speech recognition experiments. The experiments performed use clean audio data and audio data corrupted by stationary white Gaussian noise at various SNRs. The proposed system reduces the word error rate (WER) by 20% to 23% relatively to audio-only speech recognition WERs, at various SNRs (0–30 dB) with additive white Gaussian noise, and by 19% relatively to audio-only speech recognition WER under clean audio conditions.
This article is part of the series Joint Audio-Visual Speech Processing.
Audio-Visual Speech Recognition Using MPEG-4 Compliant Visual Features
Department of Electrical and Computer Engineering, Northwestern University, 2145 North Sheridan Road, Evanston, IL 60208-3118, USA
EURASIP Journal on Advances in Signal Processing 2002, 2002:150948 doi:10.1155/S1110865702206162
The electronic version of this article is the complete one and can be found online at: http://asp.eurasipjournals.com/content/2002/11/150948
Received: | 3 December 2001 |
Revisions received: | 19 May 2002 |
Published: | 28 November 2002 |
© 2002 Aleksic et al.
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