Advances in computer processing power and emerging algorithms are allowing new ways of envisioning human-computer interaction. Although the benefit of audio-visual fusion is expected for affect recognition from the psychological and engineering perspectives, most of existing approaches to automatic human affect analysis are unimodal: information processed by computer system is limited to either face images or the speech signals. This paper focuses on the development of a computing algorithm that uses both audio and visual sensors to detect and track a user's affective state to aid computer decision making. Using our multistream fused hidden Markov model (MFHMM), we analyzed coupled audio and visual streams to detect four cognitive states (interest, boredom, frustration and puzzlement) and seven prototypical emotions (neural, happiness, sadness, anger, disgust, fear and surprise). The MFHMM allows the building of an optimal connection among multiple streams according to the maximum entropy principle and the maximum mutual information criterion. Person-independent experimental results from 20 subjects in 660 sequences show that the MFHMM approach outperforms face-only HMM, pitch-only HMM, energy-only HMM, and independent HMM fusion, under clean and varying audio channel noise condition.

The ability of a computer to detect and appropriately respond to changes in a user's affective state has significant implications to human-computer interaction (HCI). In this paper, we present our efforts toward audio-visual affect recognition on 11 affective states customized for HCI application (four cognitive/motivational and seven basic affective states) of 20 nonactor subjects. A smoothing method is proposed to reduce the detrimental influence of speech on facial expression recognition. The feature selection analysis shows that subjects are prone to use brow movement in face, pitch and energy in prosody to express their affects while speaking. For person-dependent recognition, we apply the voting method to combine the frame-based classification results from both audio and visual channels. The result shows 7.5% improvement over the best unimodal performance. For person-independent test, we apply multistream HMM to combine the information from multiple component streams. This test shows 6.1% improvement over the best component performance

Advances in computer processing power and emerging algorithms are allowing new ways of envisioning human computer interaction. This paper focuses on the development of a computing algorithm that uses audio and visual sensors to detect and track a user's affective state to aid computer decision making. Using our multi-stream fused hidden Markov model (MFHMM), we analyzed coupled audio and visual streams to detect 11 cognitive/emotive states. The MFHMM allows the building of an optimal connection among multiple streams according to the maximum entropy principle and the maximum mutual information criterion. Person-independent experimental results from 20 subjects in 660 sequences show that the MFHMM approach performs with an accuracy of 80.61% which outperforms face-only HMM, pitch-only HMM, energy-only HMM, and independent HMM fusion.

The ability of a computer to detect and appropriately respond to changes in a user's affective state has significant implications to human-computer interaction (HCI). To more accurately simulate the human ability to assess affects through multi-sensory data, automatic affect recognition should also make use of multimodal data. In this paper, we present our efforts toward audio-visual affect recognition. Based on psychological research, we have chosen affect categories based on an activation-evaluation space which is robust in capturing significant aspects of emotion. We apply the Fisher boosting learning algorithm which can build a strong classifier by combining a small set of weak classification functions. Our experimental results show with 30 Fisher features, the testing error rates of our bimodal affect recognition is about 16% on the evaluation axis and 13% on the activation axis.