Daisy-TTS: Simulating Wider Spectrum of Emotions via Prosody Embedding Decomposition

We often verbally express emotions in a multifaceted manner, they may vary in their intensities and may be expressed not just as a single but as a mixture of emotions. This wide spectrum of emotions is well-studied in the structural model of emotions, which represents variety of emotions as derivative products of primary emotions with varying degrees of intensity. In this paper, we propose an emotional text-to-speech design to simulate a wider spectrum of emotions grounded on the structural model. Our proposed design, Daisy-TTS, incorporates a prosody encoder to learn emotionally-separable prosody embedding as a proxy for emotion. This emotion representation allows the model to simulate: (1) Primary emotions, as learned from the training samples, (2) Secondary emotions, as a mixture of primary emotions, (3) Intensity-level, by scaling the emotion embedding, and (4) Emotions polarity, by negating the emotion embedding. Through a series of perceptual evaluations, Daisy-TTS demonstrated overall higher emotional speech naturalness and emotion perceiveability compared to the baseline.

Nix-TTS: An Incredibly Lightweight End-to-End Text-to-Speech Model via Non End-to-End Distillation

We propose Nix-TTS, a lightweight neural TTS (Text-to-Speech) model achieved by applying knowledge distillation to a powerful yet large-sized generative TTS teacher model. Distilling a TTS model might sound unintuitive due to the generative and disjointed nature of TTS architectures, but pre-trained TTS models can be simplified into encoder and decoder structures, where the former encodes text into some latent representation and the latter decodes the latent into speech data. We devise a framework to distill each component in a non end-to-end fashion. Nix-TTS is end-to-end (vocoder-free) with only 5.23M parameters or up to 82\% reduction of the teacher model, it achieves over 3.26$\times$ and 8.36$\times$ inference speedup on Intel-i7 CPU and Raspberry Pi respectively, and still retains a fair voice naturalness and intelligibility compared to the teacher model. We publicly release Nix-TTS pretrained models and audio samples in English (https://github.com/rendchevi/nix-tts).

Which Student is Best? A Comprehensive Knowledge Distillation Exam for Task-Specific BERT Models

We perform knowledge distillation (KD) benchmark from task-specific BERT-base teacher models to various student models: BiLSTM, CNN, BERT-Tiny, BERT-Mini, and BERT-Small. Our experiment involves 12 datasets grouped in two tasks: text classification and sequence labeling in the Indonesian language. We also compare various aspects of distillations including the usage of word embeddings and unlabeled data augmentation. Our experiments show that, despite the rising popularity of Transformer-based models, using BiLSTM and CNN student models provide the best trade-off between performance and computational resource (CPU, RAM, and storage) compared to pruned BERT models. We further propose some quick wins on performing KD to produce small NLP models via efficient KD training mechanisms involving simple choices of loss functions, word embeddings, and unlabeled data preparation.