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Figure 1: A deep learning approach is used to generate upper-face gestures and is trained using facial gestures, audio features, and speech text extracted from TED talks.

We propose a multimodal speech driven approach to generate 2D upper-body gestures for virtual agents, in the communicative style of different speakers, seen or unseen by our model during training. Upper-body gestures of a source speaker are generated based on the content of his/her multimodal data -speech acoustics and text semantics. The synthesized source speaker's gestures are conditioned on the multimodal style representation of the target speaker. Our approach is zero-shot, and can generalize the style transfer to new unseen speakers, without any additional training. An objective evaluation is conducted to validate our approach.

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Modeling virtual agents with behavior style is one factor for personalizing human-agent interaction. We propose an efficient yet effective machine learning approach to synthesize gestures driven by prosodic features and text in the style of different speakers including those unseen during training. Our model performs zero-shot multimodal style transfer driven by multimodal data from the PATS database containing videos of various speakers. We view style as being pervasive; while speaking, it colors the communicative behaviors expressivity while speech content is carried by multimodal signals and text. This disentanglement scheme of content and style allows us to directly infer the style embedding even of a speaker whose data are not part of the training phase, without requiring any further training or fine-tuning. The first goal of our model is to generate the gestures of a source speaker based on the content of two input modalities–Mel spectrogram and text semantics. The second goal is to condition the source speaker's predicted gestures on the multimodal behavior style embedding of a target speaker. The third goal is to allow zero-shot style transfer of speakers unseen during training without re-training the model. Our system consists of two main components: (1) a speaker style encoder network that learns to generate a fixed-dimensional speaker embedding style from a target speaker multimodal data (mel-spectrogram, pose, and text) and (2) a sequence-to-sequence synthesis network that synthesizes gestures based on the content of the input modalities—text and mel-spectrogram—of a source speaker and conditioned on the speaker style embedding. We evaluate that our model is able to synthesize gestures of a source speaker given the two input modalities and transfer the knowledge of target speaker style variability learned by the speaker style encoder to the gesture generation task in a zero-shot setup, indicating that the model has learned a high-quality speaker representation. We conduct objective and subjective evaluations to validate our approach and compare it with baselines.