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Recent advancements in spontaneous text-to-speech (TTS) have enabled the realistic synthesis of creaky voice, a voice quality known for its diverse pragmatic and paralinguistic functions. In this study, we used synthesized creaky voice in perceptual tests, to explore how listeners without formal training perceive two distinct types of creaky voice. We annotated a spontaneous speech corpus using creaky voice detection tools and modified a neural TTS engine with a creaky phonation embedding to control the presence of creaky phonation in the synthesized speech. We performed an objective analysis using a creak detection tool which revealed significant differences in creaky phonation levels between the two creaky voice types and modal voice. Two subjective listening experiments were performed to investigate the effect of creaky voice on perceived certainty, valence, sarcasm, and turn finality. Participants rated non-positional creak as less certain, less positive, and more indicative of turn finality, while positional creak was rated significantly more turn final compared to modal phonation., QC 20240701Part of ISBN 978-249381410-4

Neural HMMs are a type of neural transducer recently proposed for sequence-to-sequence modelling in text-to-speech. They combine the best features of classic statistical speech synthesis and modern neural TTS, requiring less data and fewer training updates, and are less prone to gibberish output caused by neural attention failures. In this paper, we combine neural HMM TTS with normalising flows for describing the highly non-Gaussian distribution of speech acoustics. The result is a powerful, fully probabilistic model of durations and acoustics that can be trained using exact maximum likelihood. Experiments show that a system based on our proposal needs fewer updates than comparable methods to produce accurate pronunciations and a subjective speech quality close to natural speech., QC 20231107

With recent advances in generative modelling, conversational systems are becoming more lifelike and capable of long, nuanced interactions. Text-to-Speech (TTS) is being tested in territories requiring natural-sounding speech that can mimic the complexities of human conversation. Hyper-realistic speech generation has been achieved, but a gap remains between the verbal behavior required for upscaled conversation, such as paralinguistic information and pragmatic functions, and comprehension of the acoustic prosodic correlates underlying these. Without this knowledge, reproducing these functions in speech has little value. We use prosodic correlates including spectral peaks, spectral tilt, and creak percentage for speech synthesis with the pragmatic functions of small talk, self-directed speech, advice, and instructions. We perform a MOS evaluation, and a suitability experiment in which our system outperforms a read-speech and conversational baseline., QC 20231009

Connected (VR-2019-05003), STANCE (VR- 2020-02396), Prosodic functions of voice quality dynamics (VR-2019-02932), CAPTivating (P20-0298)

As part of the PSST challenge, we explore how data augmentations, data sources, and model size affect phoneme transcription accuracy on speech produced by individuals with aphasia. We evaluate model performance in terms of feature error rate (FER) and phoneme error rate (PER). We find that data augmentations techniques, such as pitch shift, improve model performance. Additionally, increasing the size of the model decreases FER and PER. Our experiments also show that adding manually-transcribed speech from non-aphasic speakers (TIMIT) improves performance when Room Impulse Response is used to augment the data. The best performing model combines aphasic and non-aphasic data and has a 21.0% PER and a 9.2% FER, a relative improvement of 9.8% compared to the baseline model on the primary outcome measurement. We show that data augmentation, larger model size, and additional non-aphasic data sources can be helpful in improving automatic phoneme recognition models for people with aphasia., QC 20220815

Spontaneous speech synthesis is a complex enterprise, as the data has large variation, as well as speech disfluencies nor-mally omitted from read speech. These disfluencies perturb the attention mechanism present in most Text to Speech (TTS) sys-tems. Explicit modelling of prosodic features has enabled intu-itive prosody modification of synthesized speech. Most pros-ody-controlled TTS, however, has been trained on read-speech data that is not representative of spontaneous conversational prosody. The diversity in prosody in spontaneous speech data allows for more wide-ranging data-driven modelling of pro-sodic features. Additionally, prosody-controlled TTS requires extensive training data and GPU time which limits accessibil-ity. We use neural HMM TTS as it reduces the parameter size and can achieve fast convergence with stable alignments for spontaneous speech data. We modify neural HMM TTS to ena-ble prosodic control of the speech rate and fundamental fre-quency. We perform subjective evaluation of the generated speech of English and Swedish TTS models and objective eval-uation for English TTS. Subjective evaluation showed a signif-icant improvement in naturalness for Swedish for the mean prosody compared to a baseline with no prosody modification, and the objective evaluation showed greater variety in the mean of the per-utterance prosodic features., QC 20220726

Much of the research investigating the perception of speaker certainty has relied on either attempting to elicit prosodic features in read speech, or artificial manipulation of recorded audio. Our novel method of controlling prosody in synthesized spontaneous speech provides a powerful tool for studying speech perception and can provide better insight into the interacting effects of prosodic features on perception while also paving the way for conversational systems which are more effectively able to engage in and respond to social behaviors. Here we have used this method to examine the combined impact of filled pause location, speech rate and f0 on the perception of speaker confidence. We found an additive effect of all three features. The most confident-sounding utterances had no filler, low f0 and high speech rate, while the least confident-sounding utterances had a medial filled pause, high f0 and low speech rate. Insertion of filled pauses had the strongest influence, but pitch and speaking rate could be used to more finely control the uncertainty cues in spontaneous speech synthesis., QC 20230322