An Overview of Affective Speech Synthesis and Conversion in the Deep Learning Era (original) (raw)

A Methodology for Controlling the Emotional Expressiveness in Synthetic Speech -a Deep Learning approach

In this project, we aim to build a Text-to-Speech system able to produce speech with a controllable emotional expressiveness. We propose a methodology for solving this problem in three main steps. The first is the collection of emotional speech data. We discuss the various formats of existing datasets and their usability in speech generation. The second step is the development of a system to automatically annotate data with emotion/expressiveness features. We compare several techniques using transfer learning to extract such a representation through other tasks and propose a method to visualize and interpret the correlation between vocal and emotional features. The third step is the development of a deep learning-based system taking text and emotion/expressiveness as input and producing speech as output. We study the impact of fine tuning from a neutral TTS towards an emotional TTS in terms of intelligibility and perception of the emotion.

Emotional speech synthesis: Applications, history and possible future

Proc. ESSV, 2009

Emotional speech synthesis is an important part of the puzzle on the long way to human-like artificial human-machine interaction. During the way, lots of stations like emotional audio messages or believable characters in gaming will be reached. This paper discusses technical aspects of emotional speech synthesis, shows practical applications based on a higher level framework and highlights new developments concerning the realization of affective speech with non-uniform unit selection based synthesis and voice transformation techniques.

Synthesis of Speech with Emotions

Proc. International Conference on Communication, Computers and Devices

This paper describes the methodology proposed by us for synthesizing speech with emotion. Our work starts with the pitch synchronous analysis of single phoneme utterances with natural emotion to obtain the linear prediction (LP) parameters. For synthesizing speech with emotion, we modify the pitch contour of a normal utterance of a single phoneme. We subsequently filter this signal using the LP parameters. The proposed technique can be used to improve the naturalness of voice in a text-to-speech system.

Improving TTS synthesis for emotional expressivity by a prosodic parameterization of affect based on linguistic analysis

Affective Speech Synthesis is quite important for various applications like storytelling, speech based user interfaces, computer games, etc. However, some studies revealed that Text-To-Speech (TTS) systems have tendency for not conveying a suitable emotional expressivity in their outputs. Due to the recent convergence of several analytical studies pertaining to affect and human speech, this problem can now be tackled by a new angle that has at its core an appropriate prosodic parameterization based on an intelligent detection of the affective clues of the input text. This, allied with recent findings on affective speech analysis, allows a suitable assignment of pitch accents, other prosodic parameters and signal properties that adhere to F0 and match the optimal parameterization for the emotion detected in the input text. Such approach allows the input text to be enriched with metainformation that assists efficiently the TTS system. Furthermore, the output of the TTS system is also postprocessed in order to enhance its affective content. Several preliminary tests confirm the validity of our approach and encourage us to continue its exploration.

Exemplar-Based Emotive Speech Synthesis

IEEE/ACM Transactions on Audio, Speech, and Language Processing

Expressive text-to-speech (E-TTS) synthesis is important for enhancing user experience in communication with machines using the speech modality. However, one of the challenges in E-TTS is the lack of a precise description of emotions. Previous categorical specifications may be insufficient for describing complex emotions. The dimensional specifications face the difficulty of ambiguity in annotation. This work advocates a new approach of describing emotive speech acoustics using spoken exemplars. We investigate methods to extract emotion descriptions from the input exemplar of emotive speech. The measures are combined to form two descriptors, based on capsule network (CapNet) and residual error network (RENet). The first is designed to consider the spatial information in the input exemplary spectrogram, and the latter is to capture the contrastive information between emotive acoustic expressions. Two different approaches are applied for conversion from the variable-length feature sequence to fixed-size description vector: (1) dynamic routing groups similar capsules to the output description; and (2) recurrent neural network's hidden states store the temporal information for the description. The two descriptors are integrated to a state-of-the-art sequence-to-sequence architecture to obtain an end-to-end architecture that is optimized as a whole towards the same goal of generating correct emotive speech. Experimental results on a public audiobook dataset demonstrate that the two exemplar-based approaches achieve significant performance improvement over the baseline system in both emotion similarity and speech quality.

Voice quality interpolation for emotional text-to-speech synthesis

2005

Synthesizing desired emotions using concatenative algorithms relies on collection of large databases. This paper focuses on the development and assessment of a simple algorithm to interpolate the intended vocal effort in existing databases in order to create new databases with intermediate levels of vocal effort. Three diphone databases in German with soft, modal, and loud voice qualities are processed with a spectral interpolation algorithm. A listening test is performed to evaluate the intended vocal effort in the original databases as well as the interpolated ones. The results show that the interpolation algorithm can create the intended intermediate levels of vocal effort given the original databases independent of the language background of the subjects.

Can we Generate Emotional Pronunciations for Expressive Speech Synthesis?

IEEE Transactions on Affective Computing

In the field of expressive speech synthesis, a lot of work has been conducted on suprasegmental prosodic features while few has been done on pronunciation variants. However, prosody is highly related to the sequence of phonemes to be expressed. This article raises two issues in the generation of emotional pronunciations for TTS systems. The first issue consists in designing an automatic pronunciation generation method from text, while the second issue addresses the very existence of emotional pronunciations through experiments conducted on emotional speech. To do so, an innovative pronunciation adaptation method which automatically adapts canonical phonemes first to those labeled in the corpus used to create a synthetic voice, then to those labeled in an expressive corpus, is presented. This method consists in training conditional random fields pronunciation models with prosodic, linguistic, phonological and articulatory features. The analysis of emotional pronunciations reveals strong dependencies between prosody and phoneme assimilation or elisions. According to perceptual tests, the double adaptation allows to synthesize expressive speech samples of good quality, but emotion-specific pronunciations are too subtle to be perceived by testers.

Empathic Machines: Using Intermediate Features as Levers to Emulate Emotions in Text-To-Speech Systems

Proceedings of the 2022 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies

We present a method to control the emotional prosody of Text to Speech (TTS) systems by using phoneme-level intermediate features (pitch, energy, and duration) as levers. As a key idea, we propose Differential Scaling (DS) to disentangle features relating to affective prosody from those arising due to acoustics conditions and speaker identity. With thorough experimental studies, we show that the proposed method improves over the prior art in accurately emulating the desired emotions while retaining the naturalness of speech. We extend the traditional evaluation of using individual sentences for a more complete evaluation of HCI systems. We present a novel experimental setup by replacing an actor with a TTS system in offline and live conversations. The emotion to be rendered is either predicted or manually assigned. The results show that the proposed method is strongly preferred over the state-of-the-art TTS system and adds the much-coveted "human touch" in machine dialogue. Audio samples for our experiments and the code are available at: https: //emtts.github.io/tts-demo/

Generative Emotional AI for Speech Emotion Recognition: The Case for Synthetic Emotional Speech Augmentation

arXiv (Cornell University), 2023

Despite advances in deep learning, current state-of-the-art speech emotion recognition (SER) systems still have poor performance due to a lack of speech emotion datasets. This paper proposes augmenting SER systems with synthetic emotional speech generated by an end-to-end text-to-speech (TTS) system based on an extended Tacotron architecture. The proposed TTS system includes encoders for speaker and emotion embeddings, a sequence-to-sequence text generator for creating Mel-spectrograms, and a WaveRNN to generate audio from the Mel-spectrograms. Extensive experiments show that the quality of the generated emotional speech can significantly improve SER performance on multiple datasets, as demonstrated by a higher mean opinion score (MOS) compared to the baseline. The generated samples were also effective at augmenting SER performance.