Pitch Trajectories Research Articles

A Virtual Actuator for Advanced Individual Pitch Control (IPC)

We present a virtual actuator concept for wind turbine control, wherein rotor force and moment references from various controllers are optimally combined to compute individual blade pitch angles. The approach aims to minimize pitch bearing wear, too. The combined references can come from known control algorithms such as speed regulation, tilt-yaw control, tower dampening and helical wake control [3]. We formulate this as an optimization problem which we solve in an MPC fashion, however, instead of the usual prediction horizon over time, we use a discretized azimuth map as our finite horizon. Serving as a unified interface for all control features utilizing individual pitching, the virtual actuator replaces the plethora of multi-blade transformations and gain-scheduling functions in traditional IPC with one coherent function. Users can directly prioritize features and input constraints on actuators and structural loads. Notably, upstream control algorithms provide rotor force or moment references rather than pitch references. Simulations showcase the virtual actuator’s ability to compute intricate pitch trajectories, surpassing the capabilities of conventional IPC methods. Our method yields novel individual pitching which optimally merges conflicting IPC objectives while minimizing actuator wear.

You good?: Examining the role of intonation and eyebrow movements in sentence type distinction

By analyzing the pitch accents, edge tones, and eyebrow movements of African American English (AAE) speakers, this study examines the coordination of prosody and co-speech gestures. Twelve self-identified AAE speakers engaged in scripted dialogues with an AAE-speaking confederate via Zoom. Half of the dialogues contained the polysemous AAE idiomatic phrase “you good” which has declarative and interrogative forms hypothesized to be distinguished by various eyebrow and intonation patterns. The other dialogues included non-idiomatic phrases semantically related to their “you good” equivalents. These dialogues were designed to explore whether the coordination patterns for the idioms occur with non-idiomatic utterances of the same sentence type. Acoustic data is prosodically annotated using the MAE-ToBI transcription system and visual eyebrow data is tracked using OpenFace 2.0, a facial landmark detection toolkit. The derived eyebrow movement trajectories are time-aligned with the pitch trajectories for the semi-automatic labeling of multimodal signals. The temporal relationship between eyebrow movement landmarks, pitch accents, and edge tones is examined to investigate how different meanings and sentence types are created through their coordination. Preliminary examination indicates intonationally similar contours for the idiomatic and non-idiomatic interrogative phrases, but shared and consistent intonational contours are not evident in the declarative data.

Neural control of lexical tone production in human laryngeal motor cortex

In tonal languages, which are spoken by nearly one-third of the world’s population, speakers precisely control the tension of vocal folds in the larynx to modulate pitch in order to distinguish words with completely different meanings. The specific pitch trajectories for a given tonal language are called lexical tones. Here, we used high-density direct cortical recordings to determine the neural basis of lexical tone production in native Mandarin-speaking participants. We found that instead of a tone category-selective coding, local populations in the bilateral laryngeal motor cortex (LMC) encode articulatory kinematic information to generate the pitch dynamics of lexical tones. Using a computational model of tone production, we discovered two distinct patterns of population activity in LMC commanding pitch rising and lowering. Finally, we showed that direct electrocortical stimulation of different local populations in LMC evoked pitch rising and lowering during tone production, respectively. Together, these results reveal the neural basis of vocal pitch control of lexical tones in tonal languages.

Multipitch estimation based on the iterative detection and separation of note events from single-channel polyphonic recordings.

Multiple fundamental frequency estimation has been extensively used in applications such as melody extraction, music transcription, instrument identification, and source separation. This paper presents an approach based on the iterative detection and extraction of note events, which are considered to be harmonic sounds characterised by a continuous pitch trajectory. Note events are assumed to be associated with musical notes being played by a single instrument, and their pitch trajectories are iteratively estimated. In every iteration, the pitch contour of the predominant note event is selected from a set of pitch estimates and used to separate its spectral energy from the input mixture in order to obtain a residual signal, which is then used as input in the next iteration. This iterative process stops when the energy of the residual is below a significance threshold. The pitch trajectories of all detected note events are then revised and reassembled to form the final set of pitch estimates for the original audio input. Evaluation of performance is conducted in different scenarios to show the potential of the proposed system, both in terms of its accuracy, and also as an initial stage in other complex tasks, such as note tracking and multipitch streaming.

Experimental Optimization Environment for Developing an Intracycle Pitch Control in Cross Flow Turbines

Cross-flow tidal turbines also known as vertical-axis turbines have not reached the efficiency as it is usual found for horizontal-axis turbines. This can be mainly accounted to the intensive development effort dedicated to the latter in the past 30 years in the area of wind energy. Less attention has been given to cross-flow turbines as they present mechanical cyclic loads that detriment their durability. Nevertheless, there is great potential for their employment in tidal energy exploitation as they are intrinsically independent from the flow direction and have a higher power output per area in farm installation. For this reason the research for cross-flow turbines have regain impulse.
 Among various approaches to improve their hydrodynamic characteristics found in the literature, the intracycle pitch control is one of the most promising one. It consists in actively pitching each blade as function of the azimuth angle.
 The present paper will introduce the overall experimental environment and methods for developing an optimal intracycle control for cross-flow turbines in tidal power generation. This is the main component of project OPTIDE at Otto-von-Guericke-University Magdeburg, Germany in cooperation with the LEGI at University Grenoble-Alpes, France and the University of Applied Sciences Magdeburg-Stendal.
 The experimental system consists of a turbine flume model equipped with a speed controlled generator. The three bladed turbine model has independent controlled pitch actuators embedded in each blade and a force sensing system in one of the blade holding arms. Local high-dynamic systems allow to control the speed of the generator and the pitch position as a function of the rotational angle of the runner i.e. pitch trajectory.
 A superimposed governing system which automates the experiment has been implemented. This allows to perform an optimization process with the experiment in the loop. Evolutionary algorithms are employed to solve the two objectives of the optimization: (1) Maximizing the efficiency by (2) minimizing the alternating structural loads on the runner. These kind of problems are usually solved with numerical simulations using finite element method (FEM) and computational fluid dynamics (CFD). However, this commonly comes with very high computational efforts and uncertainty. For this reason in our approach simulations are replaced by an experimental optimization technique.
 The optimization cycle implemented in the superimposed governing system chooses a set of individuals (pitch trajectories) for each generation on base of the genetic algorithm. Each pitch trajectory is performed sequentially while power output and loads are measured. This allows to evaluate each individual in about one minute. The best individuals are then the base for the offspring of the new generation. Cross-over from best performing parents and subsequent mutation ensure both, convergence and a thorough exploration of the entire design space.
 It is expected that this method will fast and reliably find the optimal pitch trajectories under various conditions. Selected cases will be analysed in detail by means of particle-image velocimetry (PIV) with synchronized force and torque measurements to research the underlying hydrodynamic mechanisms and the effects of the flow control performed by the pitching motion.

Sound-meaning mapping: Verbal imitation of Super Mario music by Yorùbá gamers

An aspect of gaming culture among Yorùbá millennials is verbally interpreting certain musical motifs of the popular videogame called Super Mario Bros. The themes of the verbal interpretations are comparable to those of music texts at traditional Yorùbá competitions. Drawing on the Yorùbá music tradition, the account in this work is that, to the gamers, the background music of the videogame performs a similar function as the music at traditional Yorùbá competitions. Semantically, the choice of words in the linguistic interpretation is conditioned by the situational contexts or scenes where the music is heard in the videogame. The results of an acoustic analysis show that the pitch contours of the linguistic interpretations resemble the pitch trajectories of the corresponding music motifs. Thus, the sequence of words in each linguistic interpretation is determined by vocal imitation. This study suggests that the linguistic processing of music does not only involve phonetic iconicity but includes contextual inference and social expectation. The interpretive moves clearly point to strong parallels between sound-meaning mapping in spoken language and music.

Tonal center of gravity predicts variation in the interpretation of rising and falling intonation in American English

In English, the pitch trajectory at the end of a phrase distinguishes assertions from questions, through falling versus rising intonation, respectively. This study asks if, within these broad classes, variation in the shape or slope of the pitch excursion is meaningful. Recent work proposes a phonological distinction between two tonally distinct sub-categories of rising intonation: shallow rises favor an assertive interpretation, while steep rises favor a question interpretation (Jeong 2018). We test an alternative analysis, where the probabilistic association between intonation and assertive/inquisitive interpretation arises not from a discrete difference between shallow and steep rises, but from meaningful variation within the rising class. We present findings from two perception experiments where listeners hear short utterances and identify the speaker’s intention to ASK or TELL. Pitch resynthesis (PSOLA) was used to create a stimulus continuum of phrase-final rising and falling F0 trajectories that vary in the slope and shape of monotonic F0 trajectories. Our results show a probabilistic relationship between interpretation (ASK/TELL) and rise variation, but do not support the previously proposed phonological distinction between shallow and steep rises. We propose a more parsimonious model of within-category variation grounded in the Tonal Center of Gravity acoustic measure (Barnes et al. 2012).

Passive periodic motion of an asymmetric spring loaded inverted pendulum hopping robot

For improving the energy efficiency of hopping robot, an asymmetric spring loaded inverted pendulum hopping model with leg mass is considered. The period orbit problem of two-legged hopping robot is investigated. Firstly, the hybrid dynamic model is constructed. Then the passive hopping gaits are found using quasi-newton optimization method. Secondly, a PD controller is implemented to track the desired pitch trajectory of the body. Through applying control during stance phase, period orbits of the robot with offset body mass is obtained. Finally, the effect of the location of the leg mass and the body mass on hopping performances is investigated.

An acoustic study of vocal expression in two genres of Yoruba oral poetry

This pilot study proposes an acoustic study of the vocal expressions in Ìjálá and Ẹ̀sà, two genres of Yorùbá oral poetry. For this study, we conducted an experiment, involving the vocalization of an original poem in speech mode, Ìjálá and Ẹ̀sà. The vocalizations were recorded and analyzed acoustically. The results of the study show that cepstral peak prominence (CPP), Hammarberg index and Energy of voiced sound below 500 Hz distinguish comparisons of Ẹ̀sà, Ìjálá and speech but are not as reliable as F0 height and vibrato. By comparing the pitch trajectories of the speech tones and poetic tunes, we show that poetry determines tone-to-tune mapping but can accommodate language when it is feasible. The results of our investigation are not only in line with the previous impressionistic observations about vocal expression in Yorùbá oral poetry but contribute with new findings. Notably, our investigation supports vocal tremor as the historical origin of vibrato in Ìjálá. As a result of this, we strongly recommend the instruments of phonetic science for the study of vocal expression in African oral poetry.

Fast online reinforcement learning control of small lift-driven vertical axis wind turbines with an active programmable four bar linkage mechanism

Maintaining high power generation for small lift-driven vertical axis wind turbines in a changing wind environment has not been well studied yet, due to the challenges inherited from the unpredictable turbulent flow-blade interaction and complex blade interferences. Herein, a fast online reinforcement learning pitch control using an active programmable four bar linkage mechanism is proposed, making it possible for turbines to quickly adapt to wind changes and maintain high power output in operation. We formulate the pitching mechanism using a drag-link configuration with a variable frame link length into an optimization problem and further solve it by the interior point algorithm under a wide range of tip speed ratios. Then, a parameter explorative policy gradient reinforcement learning method is designed for the turbine to adaptively tune the frame link length. Since the design significantly reduces the number of parameters needed to depict a whole pitch trajectory, the proposed online learning process can converge quickly, making it capable of handling complex wind conditions in an urban environment. The transient behavior overlooked in much of the literature is also studied. Comparisons to two benchmarks have demonstrated that our proposed system has a superior performance.

Strike or ball? Batters know it better: an fMRI study of action anticipation in baseball players.

To assess whether the brain processes of action anticipation are modulated differently by perceptual and motor experiences, baseball batters, pitchers, and non-players were asked to predict the fate of pitching actions (strike or ball) while undergoing functional magnetic resonance imaging. Results showed both batters (perceptual experts of pitching action) and pitchers (motor experts) were more accurate than non-players. Furthermore, batters demonstrated higher perceptual sensitivity in discriminating strikes than non-players. All groups engaged the action observation network, putamen, and cerebellum during anticipation, while pitchers showed higher activity than non-players in the left premotor cortex, which has been implicated in the internal simulation of observed action. Only batters exhibited differences in strike versus ball pitches in their left ventral extrastriate cortex, which might be associated with the processing of relevant visual information conveyed by the observed pitcher's movement kinematics and pitch trajectory. Moreover, all groups showed higher activity selectively in the striatum, thalamus, sensorimotor cortices, and cerebellum during correct predictions than during incorrect ones, with most widespread activation in batters, reinforcing the greater involvement of the sensorimotor system in perceptual experience. Our findings demonstrate that perceptual experience might enhance action anticipation ability to a greater extent than motor experience, with overlapping but specific neural underpinnings.

Autonomous Underwater Vehicle Depth and Pitch Trajectory Tracking Using Fiber-Reinforced Elastomer Bladders for Buoyancy Control

This article presents a variable buoyancy system that uses cephalopod-inspired, fiber-reinforced elastomer membranes as bladders to enable model-based depth and pitch control of an autonomous underwater vehicle. The fiber reinforcement allows for a single measurement of each membrane to fully define the geometry of the membrane, regardless of the membrane’s orientation or level of inflation. This allows for precise control of each bladder’s enclosed water mass and center of mass by adjusting the differential pressure between the inside of the bladder and the vehicle’s cabin using water from the environment as the working fluid. Positioning bladders at the fore and aft of the vehicle enables control of both the vehicle’s density and center of mass while minimizing center of mass disturbances due to sloshing in and gravitational loads on the membranes. A nonlinear, adaptive, backstepping, trajectory-tracking controller is presented and proven to be asymptotically stable with Lyapunov stability analysis. The advantages of the proposed variable buoyancy system and controller are demonstrated through simulation and validated with 2 degree of freedom depth and pitch step and trajectory-tracking experiments in a large water tank. We evaluate the performance of the bladders and controller on the CephaloBot, an autonomous underwater vehicle designed and built by our group.

Impact of Startling Acoustic Stimuli on Word Repetition in Individuals With Aphasia and Apraxia of Speech Following Stroke.

The StartReact effect, whereby movements are elicited by loud, startling acoustic stimuli (SAS), allows the evaluation of movements when initiated through involuntary circuitry, before auditory feedback. When StartReact is applied during poststroke upper extremity movements, individuals exhibit increased muscle recruitment, reaction times, and reaching distances. StartReact releases unimpaired speech with similar increases in muscle recruitment and reaction time. However, as poststroke communication disorders have divergent neural circuitry from upper extremity tasks, it is unclear if StartReact will enhance speech poststroke. Our objective is to determine if (a) StartReact is present in individuals with poststroke aphasia and apraxia and (b) SAS exposure enhances speech intelligibility. We remotely delivered startling, 105-dB white noise bursts (SAS) and quiet, non-SAS cues to 15 individuals with poststroke aphasia and apraxia during repetition of six words. We evaluated average word intensity, pitch, pitch trajectories, vowel formants F1 and F2 (first and second formants), phonemic error rate, and percent incidence of each SAS versus non-SAS-elicited phoneme produced under each cue type. For SAS trials compared to non-SAS, speech intensity increased (∆ + 0.6 dB), speech pitch increased (∆ + 22.7 Hz), and formants (F1 and F2) changed, resulting in a smaller vowel space after SAS. SAS affected pitch trajectories for some, but not all, words. Non-SAS trials had more stops (∆ + 4.7 utterances) while SAS trials had more sustained phonemes (fricatives, glides, affricates, liquids; ∆ + 5.4 utterances). SAS trials had fewer distortion errors but no change in substitution errors or overall error rate compared to non-SAS trials. We show that stroke-impaired speech is susceptible to StartReact, evidenced by decreased intelligibility due to altered formants, pitch trajectories, and articulation, including increased incidence of sounds that could not be produced without SAS. Future studies should examine the impact of SAS on voluntary speech intelligibility and clinical measures of aphasia and apraxia.

A reversal of the song advantage in vocal pitch imitation.

Previous experiments have documented an advantage for vocal pitch-matching when participants sing back a short melody, in contrast to when participants attempt to imitate the pitch contour of spoken English. These results appear to confirm recent claims that music involves greater precision of pitch than speech. A re-analysis of these data is reported here that focuses on imitation of pitch trajectories within sung notes or spoken syllables. When analyzed this way, the domain-based difference reverses and speech imitation exhibits an advantage relative to song imitation. These results suggest that domain-specific advantages in imitation vary as a function of timescale.

Cross-Speaker Emotion Disentangling and Transfer for End-to-End Speech Synthesis

The cross-speaker emotion transfer task in text-to-speech (TTS) synthesis particularly aims to synthesize speech for a target speaker with the emotion transferred from reference speech recorded by another (source) speaker. During the emotion transfer process, the identity information of the source speaker could also affect the synthesized results, resulting in the issue of speaker leakage, i.e., synthetic speech may have the voice identity of the source speaker rather than the target speaker. This paper proposes a new method with the aim to synthesize controllable emotional expressive speech and meanwhile maintain the target speaker’s identity in the cross-speaker emotion TTS task. The proposed method is a Tacotron2-based framework with emotion embedding as the conditioning variable to provide emotion information. Two emotion disentangling modules are contained in our method to 1) get speaker-irrelevant and emotion-discriminative embedding, and 2) explicitly constrain the emotion and speaker identity of synthetic speech to be that as expected. Moreover, we present an intuitive method to control the emotion strength in the synthetic speech for the target speaker. Specifically, the learned emotion embedding is adjusted with a flexible scalar value, which allows controlling the emotion strength conveyed by the embedding. Extensive experiments have been conducted on a Mandarin disjoint corpus, and the results demonstrate that the proposed method is able to synthesize reasonable emotional speech for the target speaker. Compared to the state-of-the-art reference embedding learned methods, our method gets the best performance on the cross-speaker emotion transfer task, indicating that our method achieves the new state-of-the-art performance on learning the speaker-irrelevant emotion embedding. Furthermore, the strength ranking test and pitch trajectories plots demonstrate that the proposed method can effectively control the emotion strength, leading to prosody-diverse synthetic speech.

Determining Actuator Requirements for Cyclic Varying Pitch Propeller for Ships

In marine applications, a cyclic varying pitch (CVP) propeller is a propeller in which the propeller blade can be cyclic-pitched. This cyclic pitching of the propeller blades is used to adapt to the local flow conditions in the non-uniform wake field that the propeller operates in, behind the ship hull. This has the potential to improve the performance of the propulsion system relative to a propeller which has fixed pitch for each revolution. The potential performance improvements include increasing the propulsion efficiency and reducing the cavitation, pressure pulses, vibrations and noise problems. However, the CVP propeller is not on the market today, and several challenges have to be addressed before the CVP propeller may be realized. One of these challenges is how to design the individual cyclic pitch mechanism for the propeller. However, before the cyclic pitch mechanism can be designed, it is necessary to know the requirements for it, such as the required pitching power and torque. The focus of the current paper is therefore to present a model for the propeller, by which it is possible to determine the loads acting on the CVP propeller blades during the cyclic pitching, and hence the actuator force/torque and power requirements. To illustrate the usefulness of the model, an example is presented, in which the loads on a CVP propeller are determined, together with the requirements for the individual cyclic pitch mechanism. The efficiency results presented are, however, not representative of the efficiency improvement that may be obtained, as neither the propeller nor the pitch trajectory has been optimised. The results do, however, serve to show the benefit and validity of the model.

Prosodic characteristics of English speakers with Alzheimer’s disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. A large amount of work has focused on the automatic detection of AD, but few have examined the underlying acoustic correlates. Through the analysis of 42 speakers (21 AD and 21 control), research by Martinez-Sanchez et al. have reported flattened pitch trajectories which distinguish Spanish-speaking AD patients from those of controls [Martinez-Sanchez et al., Psicothema 24(1), 16–21 (2012)]. The present study aims to determine whether a similar effect is found in a large-scale study of English speakers with AD. Prosogram [Mertens, in Proceedings of Speech Prosody (2004)] was used to assess pitch trajectories of 203 English-speaking participants (128 AD and 75 control) from Dementiabank’s Pitt Corpus [Becker et al., Arch. Neurol. 51(6), 585–594 (1994)]. AD patients exhibited greater pitch range and trajectories across phonation than controls, both within and across syllables. These preliminary findings conflict with previous observations of a flattened prosodic profile for AD patients. A possible reason for this discrepancy is a difference in speech elicitation tasks. Previous studies on Spanish-speakers used reading and delayed pronunciation tasks, whereas the present study utilizes a picture description task, a more natural elicitation method.

Investigating the origins of pitch modulation in flute vibrato

Like most musicians, flute players often add vibrato to their playing for expressive effect. This is accomplished by a periodic modulation of the supplied air pressure resulting in significant amplitude and timbre variations of the resulting sound. However, a sizeable modulation in pitch also results in most cases with a width ranging from 20 to 50 cents of total variation. This work investigates the physical origins of this pitch variation based on an analysis of multiple databases of flute vibrato tones. Detailed tracking of the amplitude and pitch trajectories of each overtone is used to characterize the extent of amplitude and frequency modulation of each partial as well as their relative correlation. A high degree of correlation between amplitude and frequency modulation tracks suggests that both variations are controlled by the same physical parameter. However, the mechanisms for pressure-controlled pitch modulation are not well understood and many physically modeled synthesis algorithms do not produce this pitch variation when the input pressure is modulated. As such, this work systematically modifies existing physical models to reproduce the characteristics of recorded vibrato tones and evaluate potential mechanisms that may underlay the observed pitch modulations.

어휘 피치 궤적의 세대별 차이: 대구방언 화자를 중심으로

This study examined the differences in lexical pitch trajectories between speakers in their 20s and 50s from Daegue speakers, using two-syllable and one-syllable minimal pairs. For two-syllable minimal pairs, speakers in their 20s showed similar pitch trajectories, but speakers in their 50s represented different pitch trajectories depending on tones. Speakers in their 20s did not show the significant F0 difference between the two syllables in [HL] and [LH] as much as speakers in their 50s. For one-syllable minimal pairs, speakers in their 50s showed partially different pitch trajectories, but speakers in their 20s did not. These results indicate that speakers in their 50s use pitch trajectory differences better than speakers in their 20s in order to distinguish lexical meaning. However, for speakers in their 50s, a gentle slope in rising-high and rising-falling pitch trajectory shows that a change in tones has been undergone.

Review: Head and Eye Movements and Gaze Tracking in Baseball Batting.

After a 30-year gap, several studies on head and eye movements and gaze tracking in baseball batting have been performed in the last decade. These baseball studies may lead to training protocols for batting. Here we review these studies and compare the tracking behaviors with those in other sports.Baseball batters are often instructed to "keep your eye on the ball." Until recently, the evidence regarding whether batters follow this instruction and if there are benefits to following this instruction was limited. Baseball batting studies demonstrate that batters tend to move the head more than the eyes in the direction of the ball at least until a saccade occurs. Foveal gaze tracking is often maintained on the ball through the early portion of the pitch, so it can be said that baseball batters do keep the eyes on the ball. While batters place gaze at or near the point of bat-ball contact, the way this is accomplished varies. In some studies, foveal gaze tracking continues late in the pitch trajectory, whereas in other studies, anticipatory saccades occur. The relative advantages of these discrepant gaze strategies on perceptual processing and motor planning speed and accuracy are discussed, and other variables that may influence anticipatory saccades including the predictability of the pitch and the level of batter expertise are described. Further studies involving larger groups with different levels of expertise under game conditions are required to determine which gaze tracking strategies are most beneficial for baseball batting.