Vocal Tract Model Research Articles

Aeroacoustic simulation of human phonation based on the flow-induced vocal fold vibrations including their contact

This paper deals with the numerical simulation of the flow induced sound as generated in the human phonation process including vocal folds (VF) contact. The hybrid approach is used allowing to separate the acoustic and the biomechanical description of the considered problem. The two-dimensional fluid–structure interaction (FSI) problem is modelled by a simplified linear elastic model coupled to the incompressible Navier–Stokes equations in the arbitrary Lagrangian–Eulerian form and special attention is paid to the treatment of the contact problem in the FSI context. Following approach of [Sváček and Horáček, 2021] the incompressible flow model is modified by an addition of fictitious porosity term and the penalization inlet boundary condition is used. Further, the Lighthill acoustic analogy is applied for calculation of sound sources and their propagation through a vocal tract model. All partial differential equations, describing the elastic body vibration, the fluid flow and the acoustics, are approximated by finite element method. Numerical results of one-sided vocal fold paralysis are presented.

Assessing accuracy of resonances obtained with reassigned spectrograms from the "ground truth" of physical vocal tract models.

The reassigned spectrogram (RS) has emerged as the most accurate way to infer vocal tract resonances from the acoustic signal [Shadle, Nam, and Whalen (2016). "Comparing measurement errors for formants in synthetic and natural vowels," J. Acoust. Soc. Am. 139(2), 713-727]. To date, validating its accuracy has depended on formant synthesis for ground truth values of these resonances. Synthesis is easily controlled, but it has many intrinsic assumptions that do not necessarily accurately realize the acoustics in the way that physical resonances would. Here, we show that physical models of the vocal tract with derivable resonance values allow a separate approach to the ground truth, with a different range of limitations. Our three-dimensional printed vocal tract models were excited by white noise, allowing an accurate determination of the resonance frequencies. Then, sources with a range of fundamental frequencies were implemented, allowing a direct assessment of whether RS avoided the systematic bias towards the nearest strong harmonic to which other analysis techniques are prone. RS was indeed accurate at fundamental frequencies up to 300 Hz; above that, accuracy was somewhat reduced. Future directions include testing mechanical models with the dimensions of children's vocal tracts and making RS more broadly useful by automating the detection of resonances.

Acoustics of Breath Noises in Human Speech: Descriptive and Three-Dimensional Modeling Approaches.

Breathing is ubiquitous in speech production, crucial for structuring speech, and a potential diagnostic indicator for respiratory diseases. However, the acoustic characteristics of speech breathing remain underresearched. This work aims to characterize the spectral properties of human inhalation noises in a large speaker sample and explore their potential similarities with speech sounds. Speech sounds are mostly realized with egressive airflow. To account for this, we investigated the effect of airflow direction (inhalation vs. exhalation) on acoustic properties of certain vocal tract (VT) configurations. To characterize human inhalation, we describe spectra of breath noises produced by human speakers from two data sets comprising 34 female and 100 male participants. To investigate the effect of airflow direction, three-dimensional-printed VT models of a male and a female speaker with static VT configurations of four vowels and four fricatives were used. An airstream was directed through these VT configurations in both directions, and their spectral consequences were analyzed. For human inhalations, we found spectra with a decreasing slope and several weak peaks below 3 kHz. These peaks show moderate (female) to strong (male) overlap with resonances found for participants inhaling with a VT configuration of a central vowel. Results for the VT models suggest that airflow direction is crucial for spectral properties of sibilants, /ç/, and /i:/, but not the other sounds we investigated. Inhalation noise is most similar to /ə/ where airflow direction does not play a role. Inhalation is realized on ingressive airflow, and inhalation noises have specific resonance properties that are most similar to /ə/ but occur without phonation. Airflow direction does not play a role in this specific VT configuration, but subglottal resonances may do. For future work, we suggest investigating the articulation of speech breathing and link it to current work on pause postures. https://doi.org/10.23641/asha.24520585.

The effects of vocal tract constrictions on aerodynamic measures in a synthetic vocal fold model.

According to nonlinear source-filter theory, as the strength of the coupling between the source and filter increases, typically by a decrease in the vocal tract cross-sectional area, the resultant increase in the inertance of the vocal tract yields an increase in the interactions between acoustic pressures within the vocal tract and the changing glottal airflow and/or the vibratory pattern of the vocal folds as noted in Titze [(2008). J. Acoust. Soc. Am. 123(4), 1902-1915]. The purpose of the current research was to examine the effects of parametric vocal tract constrictions mimicking epilaryngeal tube and lip narrowing on aerodynamic measures in a dynamic self-oscillating physical model of the vocal folds and vocal tract. Multilayered silicone vocal fold models were created based on Murray and Thomson [(2011). J. Visualized Exp. 58, e3498] and Murray and Thomson [(2012). J. Acoust. Soc. Am. 132(5), 3428-3438] and mounted to a simple synthetic trachea and supraglottal vocal tract model. Four constriction cross-sectional areas were examined at two locations (i.e., at the epilarynx and lip regions). Phonation threshold pressure and flow were measured at phonation onset and offset using four M5-CONV vocal fold models. Results indicated that both constriction magnitude and location are relevant factors in determining glottal aerodynamics. In general, a narrow epilarynx tube or lip constriction resulted in the lowest onset pressures and airflows while the no vocal tract condition resulted in the highest onset pressures and airflows.

The babble of articulatory learning networks

Articulatory learning models utilize traditional neural network approaches to model speech. However,they differ in their inclusion of an intermediary step in which the model is trained to produce sound utilizing a physical model of the human vocal tract. This style of training is theoretically able to represent the impact of the physical nature of the human vocal tract on language in a way that is more directly translatable to the physical world. This project seeks to create an articulatory learning model which is trained to recognize and repeat input sounds utilizing the University of Wisconsin’s X-Ray Microbeam Database. We attempt this utilizing an inverse model which seeks to predict the vocal tract configuration of a given speech signal, and a forward model which predicts the acoustic form produced by vocal tract configurations. Further, we analyze the performance of the model across various training lengths to investigate the comparison to child language learning that is commonly made when implementing models of this type. Should this analysis of articulatory learners be valid, we look to find commonalities in the phonetic patterning of articulatory learning neural networks and those observed in the phonetic acquisition stages of child language development.

MGlif: A software tool for manual glottal inverse filtering

Despite decades of advances in automated estimation of the voice source (glottal flow) from the speech signal, manual glottal inverse filtering remains the gold standard; yet, options are limited regarding available software tools. Here, a new software application for glottal-flow estimation is introduced, with a graphical user interface designed for manual specification and tuning of inverse-filter parameters while results are updated and displayed in real-time. The user can flexibly control the signal polarity and sampling rate, the analysis frame position and duration, and the type of window and preemphasis for vocal-tract modeling. The tunable inverse-filter parameters are the frequencies and bandwidths of vocal-tract poles and zeros, and the lip-radiation coefficient. A single window displays graphical information in several panels: the speech waveform (scrollable), the selected frame, its log-power spectrum before and after preemphasis, the model spectrum including vocal-tract and lip-radiation effects, the estimated glottal-flow waveform, its derivative, and their log-power spectra. All information pertaining to an analysis may be saved at any time, ready to be reloaded for review or analysis resumption. Key data may also be exported for further use outside the application. The software will be made freely available to the research community.

Real-Time Vocal Tract Model for Elongation of Segment Lengths in a Waveguide Model

A vocal tract model based on a digital waveguide is presented in which the vocal tract has been decomposed into uniform cylindrical segments of variable lengths. We present a model for the real-time numerical solution of the digital waveguide equations in a uniform tube with the temporally varying cross section. In the current work, the uniform cylindrical segments of the vocal tract may have their different lengths, the time taken by the sound wave to propagate through a cylindrical segment in an axial direction may not be an integer multiple of each other. In such a case, the delay in an axial direction is necessarily a fractional delay. For the approximation of fractional-delay filters, Lagrange interpolation is used in the current model. Variable length of the individual segment of the vocal tract enables the model to produce realistic results. These results are validated with accurate benchmark model. The proposed model has been devised to elongate or shorten any arbitrary cylindrical segment by a suitable scaling factor. This model has a single algorithm and there is no need to make section of segments for elongation or shortening of the intermediate segments. The proposed model is about 23% more efficient than the previous model.

An Acoustic Simulation Method of the Japanese Vowels /i/ and /u/ by Using the Boundary Element Method

This study aimed to establish and verify the validity of an acoustic simulation method during sustained phonation of the Japanese vowels /i/ and /u/. The study participants were six healthy adults. First, vocal tract models were constructed based on computed tomography (CT) data, such as the range from the frontal sinus to the glottis, during sustained phonation of /i/ and /u/. To imitate the trachea, after being virtually extended by 12 cm, cylindrical shapes were then added to the vocal tract models between the tracheal bifurcation and the lower part of the glottis. Next, the boundary element method and the Kirchhoff–Helmholtz integral equation were used for discretization and to represent the wave equation for sound propagation, respectively. As a result, the relative discrimination thresholds of the vowel formant frequencies for /i/ and /u/ against actual voice were 1.1–10.2% and 0.4–9.3% for the first formant and 3.9–7.5% and 5.0–12.5% for the second formant, respectively. In the vocal tract model with nasal coupling, a pole–zero pair was observed at around 500 Hz, and for both /i/ and /u/, a pole–zero pair was observed at around 1000 Hz regardless of the presence or absence of nasal coupling. Therefore, the boundary element method, which produces solutions by analysis of boundary problems rather than three-dimensional aspects, was thought to be effective for simulating the Japanese vowels /i/ and /u/ with high validity for the vocal tract models encompassing a wide range, from the frontal sinuses to the trachea, constructed from CT data obtained during sustained phonation.

Deep Reinforcement Learning for Articulatory Synthesis in a Vowel-to-Vowel Imitation Task

Articulatory synthesis is one of the approaches used for modeling human speech production. In this study, we propose a model-based algorithm for learning the policy to control the vocal tract of the articulatory synthesizer in a vowel-to-vowel imitation task. Our method does not require external training data, since the policy is learned through interactions with the vocal tract model. To improve the sample efficiency of the learning, we trained the model of speech production dynamics simultaneously with the policy. The policy was trained in a supervised way using predictions of the model of speech production dynamics. To stabilize the training, early stopping was incorporated into the algorithm. Additionally, we extracted acoustic features using an acoustic word embedding (AWE) model. This model was trained to discriminate between different words and to enable compact encoding of acoustics while preserving contextual information of the input. Our preliminary experiments showed that introducing this AWE model was crucial to guide the policy toward a near-optimal solution. The acoustic embeddings, obtained using the proposed approach, were revealed to be useful when applied as inputs to the policy and the model of speech production dynamics.

Morphological and acoustic modeling of the vocal tract

In speech production, the anatomical morphology forms the substrate on which the speakers build their articulatory strategy to reach specific articulatory-acoustic goals. The aim of this study is to characterize morphological inter-speaker variability by building a shape model of the full vocal tract including hard and soft structures. Static magnetic resonance imaging data from 41 speakers articulating altogether 1947 phonemes were considered, and the midsagittal articulator contours were manually outlined. A phoneme-independent average-articulation representative of morphology was calculated as the speaker mean articulation. A principal component analysis-driven shape model was derived from average-articulations, leading to five morphological components, which explained 87% of the variance. Almost three-quarters of the variance was related to independent variations of the horizontal oral and vertical pharyngeal lengths, the latter capturing male-female differences. The three additional components captured shape variations related to head tilt and palate shape. Plane wave propagation acoustic simulations were run to characterize morphological components. A lengthening of 1 cm of the vocal tract in the vertical or horizontal directions led to a decrease in formant values of 7%-8%. Further analyses are required to analyze three-dimensional variability and to understand the morphological-acoustic relationships per phoneme. Average-articulations and model code are publicly available (https://github.com/tonioser/VTMorphologicalModel).

Acoustics demonstration extravaganza

The Education in Acoustics and Physical Acoustics committees are pleased to present an Acoustics Demonstration Extravaganza - a showcase of demonstrations and apparatus to inspire and challenge your understanding of acoustics and vibration phenomena. In the spirit of the “Circus of Acoustics” demonstration show from the June 2002 ASA 143 Pittsburgh meeting [J. Acoust. Soc., Am., 111, 5, Pt2, p. 2451, (2002) session 4pPAb] this session will consist of several short demonstrations covering a wide variety of acoustics and vibration topics. Among the demonstrations intended to be shown are the following (there may be some last-minute additions or substitutions depending on equipment and presenter availability): Simple Sound Sources: Directory patterns and frequency spectrum characteristics of monopole, dipole, and quadrupole sources, the pressure doubling effect of a baffle, and a beam-forming array. Radiation of Sound from Plates: Demonstration of the radiated intensity from various vibrational modes of a simply supported thin plate. Strings of Pearls: Modes of vibration for a N-DOF mass-spring system and standing waves on a compound string comprised of a two string segments with different densities. Burning Wire of Death: Standing waves on a nichrome wire carrying a high current so it glows red at nodes. The Song of the Singing Rod: The singing rod demonstration is commonly used to describe longitudinal waves in a free-free rod. However, if the length of the rod is adjusted just right, a nonlinear pulsating effect is observed resulting from modal coupling of transverse bending modes and either subharmonic longitudinal modes or torsional modes. Nonlinear Oscillations in a Membrane: A membrane is driven with a large amplitude, so the vibration becomes nonlinear. As the frequency sweeps up and then down, the amplitude jumps and follows a hysteresis loop characteristic of a stiffening nonlinear spring. Demonstration apparatus of the Cochlea (designed by Robert Keolian): A mechanical hydrodynamic analog model of the basilar membrane in the cochlea illustrating von Békésy's classical passive tonotopic traveling wave as an explanation of how the ear responds to different frequencies. Acoustic Resonator Rockets: A pair of lightweight Helmholtz Resonators, balanced on a pivot, will rotate when exposed to a loud amplitude sound at their resonance frequency. Acoustic Filters: An audible and visual demonstration of low-pass, high-pass, and band-stop acoustic filters using PVC pipes. Vocal Tract Models: A collection of short pipes with varying cross-sectional areas (designed by Takayuki Arai) that produce vowel sounds and may be used to model the acoustics of speech. Speed of Sound: A series of short demonstrations that illustrate the effect of temperature on the speed of sound in air, sound speed dependence on gas composition, and the effect of bubbles on the speed of sound in water. Fluid Loading of a Plate: A comparison of the vibration response of a vibrating plate, and the audibly radiated sound, when the plate is in air versus submerged in water. Rectangular Waveguide: Plane waves will propagate down a waveguide without decay at all frequencies, but non-plane wave modes will propagate only if driven above the cut-on frequency. When driven below the cut-on frequency, non-plane modes become evanescent and decay exponentially. Baseball Bat Piano: The hollow cylindrical barrels of metal and composite softball bats exhibit cylindrical shell vibrational modes. A collection of softball bats with hoop-mode frequencies corresponding to a musical scale may be played like a xylophone.

VOLERE: Leakage Resilient User Authentication Based on Personal Voice Challenges

Voiceprint Authentication as a Service (VAaS) offers great convenience due to ubiquity, generality, and usability. Despite its attractiveness, it suffers from user voiceprint leakage over the air or at the cloud, which intrudes user voice privacy and retards its wide adoption. The literature still lacks an effective solution on this issue. Traditional methods based on cryptography are too complex to be practically deployed while other approaches distort user voiceprints, which hinders accurate user identification. In this article, we propose a leakage resilient user authentication cloud service with privacy preservation based on random personal voice challenges, named VOLERE (VOice LEakage REsilient). It applies a novel voiceprint synthesis method based on a Log Magnitude Approximate (LMA) vocal tract model to fuse original voices of different speaking modes in order to generate a synthesized voiceprint for authentication. Thus, raw voiceprints of users can be well protected. We implement VOLERE and conduct a series of user tests. Experimental results show sound performance of VOLERE regarding authentication accuracy, efficiency, stability, leakage resilience and user acceptance. In particular, its authentication accuracy is reasonably stable regardless user nationality, gender, age, elapsed time, and environment, as well as variance of speaking modes.

TorchDIVA: An extensible computational model of speech production built on an open-source machine learning library.

The DIVA model is a computational model of speech motor control that combines a simulation of the brain regions responsible for speech production with a model of the human vocal tract. The model is currently implemented in Matlab Simulink; however, this is less than ideal as most of the development in speech technology research is done in Python. This means there is a wealth of machine learning tools which are freely available in the Python ecosystem that cannot be easily integrated with DIVA. We present TorchDIVA, a full rebuild of DIVA in Python using PyTorch tensors. DIVA source code was directly translated from Matlab to Python, and built-in Simulink signal blocks were implemented from scratch. After implementation, the accuracy of each module was evaluated via systematic block-by-block validation. The TorchDIVA model is shown to produce outputs that closely match those of the original DIVA model, with a negligible difference between the two. We additionally present an example of the extensibility of TorchDIVA as a research platform. Speech quality enhancement in TorchDIVA is achieved through an integration with an existing PyTorch generative vocoder called DiffWave. A modified DiffWave mel-spectrum upsampler was trained on human speech waveforms and conditioned on the TorchDIVA speech production. The results indicate improved speech quality metrics in the DiffWave-enhanced output as compared to the baseline. This enhancement would have been difficult or impossible to accomplish in the original Matlab implementation. This proof-of-concept demonstrates the value TorchDIVA can bring to the research community. Researchers can download the new implementation at: https://github.com/skinahan/DIVA_PyTorch.

A 3D Geometry Model of Vocal Tract Based on Smart Internet of Things

The Internet of Things (IoT) plays an essential role in the current and future generations of information, network, and communication development and applications. This research focuses on vocal tract visualization and modeling, which are critical issues in realizing inner vocal tract animation. That is applied in many fields, such as speech training, speech therapy, speech analysis and other speech production-related applications. This work constructed a geometric model by observation of Magnetic Resonance Imaging data, providing a new method to annotate and construct 3D vocal tract organs. The proposed method has two advantages compared with previous methods. Firstly it has a uniform construction protocol for all speech organs. Secondly, this method can build correspondent feature points between different speech organs. There are less than three control parameters can be used to describe every speech organ accurately, for which the accumulated contribution rate is more than 88%. By means of the reconfiguration, the model error is less than 1.0 mm. Regarding to the data from Chinese Magnetic resonance imaging (MRI), this is the first work of 3D vocal tract model. It will promote the theoretical research and development of the intelligent Internet of Things facing speech generation-related issues.

Realistic three-dimensional avian vocal tract model demonstrates how shape affects sound filtering (Passer domesticus).

Despite the complex geometry of songbird's vocal system, it was typically modelled as a tube or with simple mathematical parameters to investigate sound filtering. Here, we developed an adjustable computational acoustic model of a sparrow's upper vocal tract (Passer domesticus), derived from micro-CT scans. We discovered that a 20% tracheal shortening or a 20° beak gape increase caused the vocal tract harmonic resonance to shift toward higher pitch (11.7% or 8.8%, respectively), predominantly in the mid-range frequencies (3-6 kHz). The oropharyngeal-oesophageal cavity (OEC), known for its role in sound filtering, was modelled as an adjustable three-dimensional cylinder. For a constant OEC volume, an elongated cylinder induced a higher frequency shift than a wide cylinder (70% versus 37%). We found that the OEC volume adjustments can modify the OEC first harmonic resonance at low frequencies (1.5-3 kHz) and the OEC third harmonic resonance at higher frequencies (6-8 kHz). This work demonstrates the need to consider the realistic geometry of the vocal system to accurately quantify its effect on sound filtering and show that sparrows can tune the entire range of produced sound frequencies to their vocal system resonances, by controlling the vocal tract shape, especially through complex OEC volume adjustments.

One-dimensional static vocal tract model in the time domain

One-dimensional static vocal tract model in the time domain

Education in basic acoustics for acoustic phonetics and speech science.

Students in acoustic phonetics and speech science classes often do not have much technical background; an intuitive means to teach acoustic phenomena to them would, thus, be useful. Regarding speech production, physical demonstrations using vocal-tract models have been shown to be an intuitive way to teach acoustic phenomena. In particular, a series of models for different purposes has been developed by Arai over the last 20+ years, including lung models, sound sources, and vocal-tract models, e.g., see Arai [J. Acoust. Soc. Am. 131(3), 2444-2454 (2012)]. Different combinations of these models are helpful for teaching a variety of related topics in the classroom. However, there are still barriers to understanding certain concepts. This study examined ways of minimizing technical explanations and mathematical formulations and maximizing intuitive understanding of seven topics. Its findings were incorporated into an education program that was used in an actual lecture conducted online. A comparison of scores of questionnaires filled out by the audience before and after the lecture showed the program's effectiveness, especially in relating how a set of harmonic waves excites a multiple-resonance system and how the vowel /a/ is produced.

Recent Research in Singing

Recent Research in Singing Donald Simonson (bio) RECENT RESEARCH IN SINGING The following list of recent research in singing is a brief sampling of dissertations/theses published during the last year. It is by no means comprehensive and reflects only a small fraction of the available documents. If you have published recent research in singing, voice pedagogy, voice science, vocal repertoire, pedagogic methodology, or other topics of interest to the membership of NATS, please send citations and abstracts to Donald Simonson at drs@iastate.edu for review and possible inclusion in future columns. ________ Bidstrup Graham, Kelly. "From Broadway to Community, the Job of a Music Director for Musical Theatre." M.A. Thesis, University of Colorado at Boulder, 2022, 67 pages; ProQuest 2681016185. "What in the world do music directors do? Despite musical theater being a billion dollar industry, the backbone of these productions, the music director, is often unknown and even less so understood within the theatre industry. In this study I interviewed nineteen music directors from across the professional and educational spectrum in search of crystallizing a common set of best practices that can be utilized by new musical directors, but more importantly, can be used by non-music directors in the industry to improve their working relationships with music directors, in order to create more musical theater in meaningful and creative ways." (ProQuest/Author Abstract) ________ May, Nicholas A. "The Effect of Nonlinear Source-Filter Interaction on Aerodynamic Measures in a Synthetic Model of the Vocal Folds and Vocal Tract." Ph.D. Dissertation 2022, Bowling Green State University, 321 pages; ProQuest 2684505746. "According to nonlinear source-filter theory, as the strength of the coupling between the source and filter increases, typically by a decrease in the vocal tract cross sectional area, the resultant increase in the inertance of the vocal tract yields an increase in the interactions between acoustic pressures within the vocal tract and the changing glottal airflow and/or the vibratory pattern of the vocal folds. The purpose of the current research was to examine the effects of parametric vocal tract constrictions mimicking epilaryngeal tube and lip narrowing on aerodynamic and projected glottal area measures in a dynamic self-oscillating physical model of the vocal folds and vocal tract. "Multilayered silicone vocal fold models were created (after Murray & Thomson, 2011, 2012) and mounted to a simple synthetic trachea and supraglottal vocal tract model. Four constriction cross sectional areas were examined at two locations yielding 16 possible experimental vocal tract conditions. Vocal fold model adduction and tension were held constant across all experimental conditions; three constant subglottal pressures were examined. "Results indicate that: 1) mean phonation threshold pressure (PTP) at onset and offset, phonation instability pressure (PIP) onset, phonation pressure range (PPR) onset, phonation threshold flow (PTF) at onset and offset, phonation instability flow (PIF) onset and offset, and phonation flow [End Page 263] range (PFR) onset and offset were all found to generally decrease given a constriction in the epilarynx tube region; 2) mean PIP offset, and PPR offset were all found to generally increase given a constriction in the epilarynx tube region; 3) mean PTP at onset and offset and PTF at onset and offset were all found to generally decrease given a constriction in the lip region; and 4) mean PIP onset and offset, PPR onset and offset, PIF onset and offset, and PFR onset and offset were all found to generally increase given a constriction in the lip region. Thus, results indicate that both constriction magnitude and location are relevant factors in determining glottal aerodynamics and projected glottal area measures." (ProQuest/Author Abstract) ________ Moreno, Amanda Marie. "An Examination of the Effects of Body Mapping Instruction on Singers' Static Standing Posture and Posture While Singing." Ph.D. Dissertation, The University of North Dakota, 2022, 159 pages; ProQuest 2682732045. "Physical posture is one of the fundamental aspects of vocal technique, and voice pedagogues suggest that effective alignment is necessary for healthy vocal production. Body Mapping (BMG) is a somatic method that focuses on the understanding and correction of errors in a person's body map to facilitate effective movement for musical activity. Because this method has balance, physical alignment, and posture as...

Analysis of Rehabilitation Occupational Therapy Techniques Based on Instrumental Music Chinese Tonal Language Spectrogram Analysis.

This paper provides an in-depth analysis of timbre-speech spectrograms in instrumental music, designs a model analysis of rehabilitation occupational therapy techniques based on the analysis of timbre-speech spectrograms in instrumental music, and tests the models for comparison. Starting from the mechanism of human articulation, this paper models the process of human expression as a time-varying linear system consisting of excitation, vocal tract, and radiation models. The system's overall architecture is designed according to the characteristics of Chinese speech and everyday speech rehabilitation theory (HSL theory). The dual judgment of temporal threshold and short-time average energy realized the phonetic length training. Tone and clear tone training were achieved by linear predictive coding technique (LPC) and autocorrelation function. Using the DTW technique, isolated word speech recognition was achieved by extracting Mel-scale Frequency Cepstral Coefficients (MFCC) parameters of speech signals. The system designs corresponding training scenes for each training module according to the extracted speech parameters, combines the multimedia speech spectrogram motion situation with the speech parameters, and finally presents the training content as a speech spectrogram, and evaluates the training results through human-machine interaction to stimulate the interest of rehabilitation therapy and realize the speech rehabilitation training of patients. After analyzing the pre- and post-test data, it was found that the p-values of all three groups were <0.05, which was judged to be significantly different. Also, all subjects changed their behavioral data during the treatment. Therefore, it was concluded that the music therapy technique could improve the patients' active gaze communication ability, verbal command ability, and active question-answering ability after summarizing the data, i.e., the hypothesis of this experiment is valid. Therefore, it is believed that the technique of timbre-speech spectrogram analysis in instrumental music can achieve the effect of rehabilitation therapy to a certain extent.

High-Resolution Three-Dimensional Hybrid MRI + Low Dose CT Vocal Tract Modeling: A Cadaveric Pilot Study

<h2>Summary</h2><h3>Objectives</h3> MRI based vocal tract models have many applications in voice research and education. These models do not adequately capture bony structures (e.g. teeth, mandible), and spatial resolution is often relatively low in order to minimize scanning time. Most MRI sequences achieve 3D vocal tract coverage at gross resolutions of 2 mm³ within a scan time of <20 seconds. Computed tomography (CT) is well suited for vocal tract imaging, but is infrequently used due to the risk of ionizing radiation. In this cadaveric study, a single, extremely low-dose CT scan of the bony structures is blended with accelerated high-resolution (1 mm³) MRI scans of the soft tissues, creating a high-resolution hybrid CT-MRI vocal tract model. <h3>Methods</h3> Minimum CT dosages were determined and a custom 16-channel airway receiver coil for accelerated high (1 mm³) resolution MRI was evaluated. A rigid body landmark based partial volume registration scheme was then applied to the images, creating a hybrid CT-MRI model that was segmented in Slicer. <h3>Results</h3> Ultra-low dose CT produced images with sufficient quality to clearly visualize the bone, and exposed the cadaver to 0.06 mSv. This is comparable to atmospheric exposures during a round trip transatlantic flight. The custom 16-channel vocal tract coil produced acceptable image quality at 1 mm³ resolution when reconstructed from ∼6 fold undersampled data. High (1 mm³) resolution MR imaging of short (<10 seconds) sustained sounds was achieved. The feasibility of hybrid CT-MRI vocal tract modeling was successfully demonstrated using the rigid body landmark based partial volume registration scheme. Segmentations of CT and hybrid CT-MRI images provided more detailed 3D representations of the vocal tract than 2 mm³ MRI based segmentations. <h3>Conclusions</h3> The method described in this study indicates that high-resolution CT and MR image sets can be combined so that structures such as teeth and bone are accurately represented in vocal tract reconstructions. Such scans will aid learning and deepen understanding of anatomical features that relate to voice production, as well as furthering knowledge of the static and dynamic functioning of individual structures relating to voice production.