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Parametric speech synthesis has received increased attention in recent years following the development of statistical HMM-based speech synthesis. However, the speech produced using this method still does not sound as natural as human speech and there is limited parametric flexibility to replicate voice quality aspects, such as breathiness. The hypothesis of this thesis is that speech naturalness and voice quality can be more accurately replicated by a HMM-based speech synthesiser using an acoustic glottal source model, the Liljencrants-Fant (LF) model, to represent the source component of speech instead of the traditional impulse train. Two different analysis-synthesis methods were developed during this thesis, in order to integrate the LF-model into a baseline HMM-based speech synthesiser, which is based on the popular HTS system and uses the STRAIGHT vocoder. The first method, which is called Glottal Post-Filtering (GPF), consists of passing a chosen LF-model signal through a glottal post-filter to obtain the source signal and then generating speech, by passing this source signal through the spectral envelope filter. The system which uses the GPF method (HTS-GPF system) is similar to the baseline system, but it uses a different source signal instead of the impulse train used by STRAIGHT. The second method, called Glottal Spectral Separation (GSS), generates speech by passing the LF-model signal through the vocal tract filter. The major advantage of the synthesiser which incorporates the GSS method, named HTS-LF, is that the acoustic properties of the LF-model parameters are automatically learnt by the HMMs. In this thesis, an initial perceptual experiment was conducted to compare the LFmodel to the impulse train. The results showed that the LF-model was significantly better, both in terms of speech naturalness and replication of two basic voice qualities (breathy and tense). In a second perceptual evaluation, the HTS-LF system was better than the baseline system, although the difference between the two had been expected to be more significant. A third experiment was conducted to evaluate the HTS-GPF system and an improved HTS-LF system, in terms of speech naturalness, voice similarity and intelligibility. The results showed that the HTS-GPF system performed similarly to the baseline. However, the HTS-LF system was significantly outperformed by the baseline. Finally, acoustic measurements were performed on the synthetic speech to investigate the speech distortion in the HTS-LF system. The results indicated that a problem in replicating the rapid variations of the vocal tract filter parameters at transitions between voiced and unvoiced sounds is the most significant cause of speech distortion. This problem encourages future work to further improve the system.

Producing an accurate model of the human voice has been the goal of researchers for a very long time, but is extremely challenging due to the complexity surrounding the way in which the voice functions. One of the more complicated aspects of modelling the voice is the fluid dynamics of the airflow, by which the process of self-oscillation of the vocal folds is sustained. This airflow also provides the only means by which the ventricular bands (two vocal fold-like structures located a short distance above the vocal folds) are driven into self-oscillation. These have been found to play a significant role in various singing styles and in voice pathologies. This study considers the airflow and flow-structure interaction in an artificial up-scaled model of the human larynx, including self-oscillating vocal folds and fixed ventricular bands. As the majority of any significant fluid-structure interaction takes place between structures found within the larynx, this thesis is limited only to examining this component of the voice organ. Particle Image Velocimetry (PIV) has been used to produce full field measurements of the flow velocity for the jet emerging from the oscillating vocal folds. An important advance in this study is the ability to observe the glottal jet from the point at which it emerges from the vocal folds, thus permitting a more complete view of the overall jet geometry within the laryngeal ventricle than in previous work. Ensemble-averaged PIV results are presented for the experimental model at different phase steps, both with and without ventricular bands, to examine their impact on the dynamics of the human larynx and the glottal jet. Finally, the three-dimensional nature of the glottal jet is considered in order to further understand and test currently held assumptions about this aspect of the jet dynamics. This was achieved by undertaking PIV in a plane perpendicular to that already considered. It is shown that the ventricular bands have an impact on the flow separation point of the glottal jet and on the deflection of the jet centreline. Furthermore, the dynamics of the vocal folds alters when ventricular bands are present, but the glottal jet is found to exhibit similar three-dimensional behaviour whether or not ventricular bands are present.

abstract: Glottal fry is a vocal register characterized by low frequency and increased signal perturbation, and is perceptually identified by its popping, creaky quality. Recently, the use of the glottal fry vocal register has received growing awareness and attention in popular culture and media in the United States. The creaky quality that was originally associated with vocal pathologies is indeed becoming “trendy,” particularly among young women across the United States. But while existing studies have defined, quantified, and attempted to explain the use of glottal fry in conversational speech, there is currently no explanation for the increasing prevalence of the use of glottal fry amongst American women. This thesis, however, proposes that conversational entrainment—a communication phenomenon which describes the propensity to modify one’s behavior to align more closely with one’s communication partner—may provide a theoretical framework to explain the growing trend in the use of glottal fry amongst college-aged women in the United States. Female participants (n = 30) between the ages of 18 and 29 years (M = 20.6, SD = 2.95) had conversations with two conversation partners, one who used quantifiably more glottal fry than the other. The study utilized perceptual and quantifiable acoustic information to address the following key question: Does the amount of habitual glottal fry in a conversational partner influence one’s use of glottal fry in their own speech? Results yielded the following two findings: (1) according to perceptual annotations, the participants used a greater amount of glottal fry when speaking with the Fry conversation partner than with the Non Fry partner, (2) statistically significant differences were found in the acoustics of the participants’ vocal qualities based on conversation partner. While the current study demonstrates that young women are indeed speaking in glottal fry in everyday conversations, and that its use can be attributed in part to conversational entrainment, we still lack a clear explanation of the deeper motivations for women to speak in a lower vocal register. The current study opens avenues for continued analysis of the sociolinguistic functions of the glottal fry register. / Dissertation/Thesis / Masters Thesis Speech and Hearing Science 2015

The work is about the estimation of vocal pulses from the speech record. Contains a description of the process of speech production, description of the instruments for the measurement of vocal pulses, an overview of software tools for estimating vocal pulses from the speech signal. Description of IAIF and Sahoo method for estimating vocal pulses. The Graphic User Interface in MATLAB is created for easier control of mentioned methods.

Objective: The purpose of this study was to identify employers’ perceptions of young women using glottal fry and the impact on hirability. Methods: A survey was created using the online survey tool, REDCapÒ, and sent to employers across the southern United States. The survey contained three voice samples consisting of a non-glottal fry voice, a glottal fry at the end of sentences voice, and a continuous glottal fry voice, fourteen semantic differential scales derived from hiring constructs, and open-ended questions on hirability. Results: Employers perceived individuals using glottal fry as more negative than the individual who used no glottal fry. Employers indicated they were less likely to hire individuals who use glottal fry compared to individuals who do not use glottal fry. Conclusion: The presence of glottal fry negatively impacts employers’ perceptions of young women and her perceived hirability. The results of this study demonstrate the relationship between vocal quality and listener perceptions.

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Tato disertační práce je zaměřena na analýzu řečového signálu za učelem detekce nemocí ovlivňujících strukturu hlasových orgánů, obzvláště těch, které mění strukturální character hlasivek. Poskytnut je přehled současných technik. Dále jsou popsány zdroje použitých nahrávek pro zdravé a nemocné mlučí. Hlavním učelem této disertační práce je popsat vypočetní postup k odhadu parametrů modelu hlasového zdroje, které umožní následnou detekci a klasifikaci nemocí hlasivek. Poskytujeme detailní popis analýzy řečových signálů, které mohou být odvozeny z parametrických modelů hlasivek.

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The purpose of this study was to investigate laryngeal movements in selected performance situations on alto saxophone. The specific research problems were to describe glottal activity in three selected musicians as they performed musical tasks with (1) various pitch ranges and registers, (2) fortissimo and pianissimo dynamic levels, (3) crescendo and decrescendo, (4) long tones with vibrato, and (5) legato and staccato styles of articulation. A fiberoptic laryngoscope was employed to gather the visual images, which were recorded on a sound synchronized video tape. A rating system was devised to provide graphic representation of the data. Results of the data indicated that the glottis was used as an airflow constrictor in certain performance situations, especially in pianissimo performance. Other conclusions were drawn, and suggestions for further research were discussed.