Specific Pitch Research Articles

The Interaction Mechanisms of Swimming Biomimetic Fish Aligned in Parallel Using the Immersed Boundary Method

In natural environments, fish almost always swim in groups. Investigating the coupled mechanism of biomimetic fish exhibiting autonomous swimming capabilities advances our understanding of fish schooling phenomena and simultaneously aids in refining the structural and formation configurations of underwater robotic vehicles. This work innovatively develops an algorithm based on the Direct-Forcing Immersed Boundary Method (DF-IBM) and implements it in an efficient, modular software program written in C++. The program accelerates the calculation process by using a multigrid method. Validation against a benchmark case of flow around a cylinder, with comparison to data from the existing literature, verifies the program’s precision with discrepancies of less than 3.6%. Based on this algorithm, the paper analyzes the incompressible viscous flow during the movement of parallel-aligned biomimetic fish. It uncovers the interaction between the fish’s motion and the surrounding flow field and also reveals the hydrodynamic mechanisms of the group motion of the parallel-aligned biomimetic fish. The flow field under varying spacing and phases between the parallel-aligned biomimetic fish proves that the interaction between the flow fields induced by the two fish bodies becomes increasingly significant when decreasing the lateral spacing from 1.4L to 0.6L. Notably, an initial lateral convergence of the fish bodies is observed, followed by a sideways swimming pattern at a particular pitch angle, accompanied by a decrement in their forward swimming velocity as they approach each other. Additionally, this study compares flow field alterations in parallel-aligned biomimetic fish with identical lateral spacing but opposing flapping phases. The findings indicate that, irrespective of the phase, the fish exhibit an initial convergence followed by a sideways motion at a specific pitch angle. However, due to disparities in the tail’s flow field, a larger pitch angle is generated when the fish swim in unison. All the findings above will provide a solid theoretical foundation for the design and optimization of underwater robotic vehicles.

Aerodynamic characteristics of the race car in pitch and roll attitude

Purpose Aerodynamics plays a crucial role in enhancing the performance of race cars. Due to the low ride height, the aerodynamic components of race cars are affected by ground effects. The changes in pitch and roll attitudes during the car’s movement impact its ride height. This study aims to analyze the aerodynamic characteristics of race cars under specific pitch and roll attitudes to understand the underlying aerodynamic mechanisms. This paper focuses on the aerodynamic characteristics of racing cars under variations in body posture associated with different vehicle ride heights. It examines not only the force and pressure distribution resulting from changes in the overall vehicle posture but also the flow field behavior of both surface flow and off‑body flow. Analyzing individual components reveals the impact of the front wing on the overall aerodynamic performance and aerodynamic balance of the racing car under these posture variations. Design/methodology/approach The grid strategy for the computational fluid dynamics (CFD) method was established under baseline conditions and compared with the results from wind tunnel experiments. The CFD approach was further employed to investigate the aerodynamic characteristics of the racing car under varying body postures associated with different vehicle ride heights. Emphasis is placed on the overall aerodynamic performance of the vehicle and the various components’ influence on the changing trends of aerodynamic forces. By considering the surface pressure distribution of the car, the primary reasons behind the changes in aerodynamic forces for each component are investigated. In addition, the surface flow and detached flow (wake and vortex distributions) of the car were observed to gain insights into the overall flow field behavior under different attitudes. Findings The findings indicate that both pitch and roll attitudes result in a considerable loss of downforce on the front wing compared with other components, thereby affecting the overall downforce and aerodynamic balance of the vehicle. Originality/value This paper focuses on the aerodynamic characteristics of racing cars under variations in body posture associated with different vehicle ride heights. It examines not only the force and pressure distribution resulting from changes in the overall vehicle posture but also the flow field behavior of both surface flow and off-body flow. Analyzing individual components reveals the impact of the front wing on the overall aerodynamic performance and aerodynamic balance of the racing car under these posture variations.

The bundengan of Wonosobo, Indonesia

The bundengan is a unique traditional musical instrument with plucked strings from Wonosobo, Central Java, Indonesia. It can produce sounds that imitate the gong (i.e., a part of the gamelan instrument). The bundengan was initially constructed by duck herders as a means of shielding themselves from inclement weather while caring for their flocks. They also engage in musical activities and singing. The distinctive sound of the bundengan is created by plucking a set of strings fitted with tiny bamboo clips using the right hand and three elongated, slender bamboo blades with the left hand. The sound effect is produced by the bandulan, a small piece of bamboo attached to the string. The tuning of the bundengan depends on the player’s instinct. This study analyzed the pitch and timbre of the bundengan strings. Using Fast Fourier Transform (FFT), the sound from a plucked string yields the frequency spectrum of the actual vibrations from the strings. The results were used to validate the frequency as heard. The results showed that the pitch from the measured frequencies is not similar to the pitch as heard. The bundengan is tuned to a pitch corresponding to the timbre rather than a specific pitch.

A melody that sings itself

In his lectures on the philosophy of nature, Maurice Merleau-Ponty interprets Jakob von Uexküll’s notion of Umwelt as akin to a melody. This essay outlines von Uexküll’s perspective on the feasibility of translating non-acoustic elements (optical: colours, shapes, and figures; haptic: tactile textures, flavours, tastes, and scents) into sounds or musical notes to compose a melody. It poses several inquiries: Does the link between melody and nature render natural entities as musical notes? Do the components of an entity constitute anatomical notes in the melody that defines the entity itself? Is it conceivable to distil every moment in life into a “note” symbol on a musical scale, characterised by specific duration, pitch, and volume? Melody, rhythm, and harmony are considered sophisticated “structures” that articulate and convey the essence of nature’s existence. Moreover, every human, every living creature, be it animal or plant, possesses a subjective “biological” interiority. The inner realm of each living subject, along with the objects in the external world, are enveloped within an atmosphere—a musical Umwelt. Humans exist within this musical milieu or atmosphere.

Optimization of Fuel Enrichment and Reactor Core Pitch Dimension in Hydride Microreactor using NSGA-II Method and OpenMC Calculation

Abstract This study focuses on the design optimization of a hydride microreactor, aimed at supporting the equitable development of electricity in remote regions of Indonesia. Its compact design, inherent safety properties, and independence from the conventional electric grid make this microreactor concept suitable for electrifying even the most inaccessible areas. Current research investigates various aspects of the hydride microreactor design, employing a standard reactor core pitch dimension of 2.4 cm and fuel enrichment of 12%. It is crucial to operate the reactor using specific concentrations of Gadolinia burnable poison to enable a shutdown in the event of a stuck rod. By optimizing only the pitch dimension and fuel enrichment, the reactor can be simulated relatively quickly without the need for burnup calculations. Ideal configuration aims for lower enrichment, an extended fuel cycle, and a relatively low power peaking factor (PPF). The optimization process utilizes the Non-dominated Sorting Genetic Algorithm – II, with the neutron multiplication factor (keff) and PPF as primary objectives. Fuel cycle and feedback reactivity are the sub-objectives that are used to identify the optimal solution from the Pareto front. The calculation process of keff, PPF, fuel cycle, and feedback reactivity coefficients for specific pitch dimensions and fuel enrichment are done by utilizing the OpenMC Monte Carlo code. The optimal configuration is obtained through four generations of NSGA-II, featuring a reactor core pitch of 2.1 cm and fuel enrichment of 10.4%. This configuration yields a keff value of 1.0712049 and a PPF value of 2,0728 at the Beginning of Life (BOL). Remarkably, this configuration enables safe operation without using burnable poison for a continuous period of 12 years, generating 1 MW of thermal power. Emphasizing the reduction of fissile material is also essential to enhance the inherent safety of the reactor.

Separation of Electron Flux in Pitch Angle Distribution During the Drift Echo Event and Shabansky Orbits Effect

AbstractThe Shabansky orbit effect can exert a significant influence on the dynamics of particle motion. However, the north‐south asymmetry of the Shabansky orbits has received relatively little attention in previous research. This study investigates this asymmetry to elucidate the recently observed phenomenon of flux separation in the pitch angle distribution during drift echo events. The asymmetry in Shabansky orbits between the northern and southern hemispheres leads to two distinct drift periods for particles with specific equatorial pitch angles, resulting in the flux separation. To quantify this phenomenon, we develop a mathematical model for the magnetic field, enabling the generation of asymmetrical Shabansky orbits. The calculated drift periods for particles with different equatorial pitch angles corresponds with the characteristics of flux separation, providing evidence to support our hypothesis that the north‐south asymmetry of Shabansky orbits is responsible for flux separation.

High-fidelity computational study of aerodynamic noise of side-by-side rotor in full configuration

This paper presents a numerical study of side-by-side rotor aircraft in full configuration during hover using high-fidelity computational fluid dynamics (CFD) and aeroacoustic simulations. CFD simulations are performed using HPCMP CREATE™-AV Helios, while acoustic calculations are conducted with PSU-WOPWOP. Overset structured grids are applied using the SA-DES turbulence model along with adaptive mesh refinement in the near- and off-body meshes. Four overlap cases at a specific collective pitch angle of 8° are considered. Results reveal a substantial influence of the fuselage on rotor performance, with improvement in the figure of merit being observed for each overlap configuration due to a partial ground effect. There is considerable increase in blade sectional thrust, pressure fluctuations, and noise levels seen in the 0% overlap configuration compared to the 25% overlap configuration. This increase is primarily due to the absence of rotor overlap, resulting in a lower induced velocity allowing for flow to travel upward, and reaching the rotor disk plane. The acoustic spectrum appears at all harmonics of the blade passing frequency for the 0% and 5% overlap configurations. In contrast, the acoustic spectrum is distinctly present only at even harmonics for the 15% and 25% overlap cases. A noise reduction benefit of 3-5 dBA is noticed in the full configuration cases having rotor overlap compared to the 0% overlap configuration. Acoustic destructive interference is observed in the directivity plot only for the 15% and 25% overlap configurations. Overall, this paper reveals that the fuselage has a significant impact on the performance, aerodynamics, and aeroacoustics of the side-by-side UAM vehicle in hover.

Trunk Instability in the Pitch, Yaw, and Roll Planes during Clinical Balance Tests: Axis Differences and Correlations to vHIT Asymmetries Following Acute Unilateral Vestibular Loss.

Clinical dynamic posturography concentrates on the pitch and roll but not on the yaw plane instability measures. This emphasis may not represent the axis instability observed in clinical stance and gait tasks for patients with balance deficits in comparison to healthy control (HC) subjects, nor the expected instability based on correlations with vestibulo-ocular reflex (VOR) deficits. To examine the axis stability changes with vestibular loss, we measured trunk sway in all three directions (pitch, roll, and yaw) during the stance and gait tasks of patients with acute unilateral vestibular neuritis (aUVN) and compared the results with those of HC. Concurrent changes in VORs were also examined and correlated with trunk balance deficits. The results of 11 patients (mean age of 61 years) recorded within 6 days of aUVN onset were compared within those of 8 age-matched healthy controls (HCs). All subjects performed a two-legged stance task-standing with eyes closed on foam (s2ecf), a semi-gait task-walking eight tandem steps (tan8), and four gait tasks-walking 3 m with head rotating laterally, pitching, or eyes closed (w3hr, w3hp, w3ec), and walking over four barriers 24 cm high, spaced 1 m apart (barr). The tasks' peak-to-peak yaw, pitch and roll angles, and angular velocities were measured with a gyroscope system (SwayStarTM) mounted at L1-3 and combined into three, axis-specific, balance control indexes (BCI), using angles (a) for the tandem gait and barriers task, and angular velocities (v) for all other tasks, as follows: axis BCI = (2 × 2ecf)v + 1.5 × (w3hr + w3hp + w3ec)v + (tan8 + 12 × barr)a. Yaw and pitch BCIs were significantly (p ≤ 0.004) greater (88 and 30%, respectively) than roll BCIs for aUVN patients. For HCs, only yaw but not pitch BCIs were greater (p = 0.002) than those of roll (72%). The order of BCI aUVN vs. HC differences was pitch, yaw, and roll at 55, 44, and 31%, respectively (p ≤ 0.002). This difference with respect to roll corresponded to the known greater yaw plane than roll plane asymmetry (40 vs. 22%) following aUVN based on VOR responses. However, the lower pitch plane asymmetry (3.5%) in VOR responses did not correspond with the pitch plane instability observed in the balance control tests. The increases in pitch plane instability in UVL subjects were, however, highly correlated with those of roll and yaw. These results indicate that greater yaw than pitch and roll trunk motion during clinical balance tasks is common for aUVN patients and HCs. However, aUVN leads to a larger increase in pitch than yaw plane instability and a smaller increase in roll plane instability. This difference with respect to roll corresponds to the known greater yaw plane than roll plane asymmetry (40 vs. 22%) following aUVN observed in VOR responses. However, the lower pitch plane asymmetry (3.5%) in VOR responses does not correspond with the enhanced movements in the pitch plane, observed in balance control tasks. Whether asymmetries in vestibular-evoked myogenic potentials (Vemps) are better correlated with the deficits in pitch plane balance control remains to be investigated. The current results provide a strong rationale for the clinical testing of directional specific balance responses, especially yaw and pitch, and the linking of balance results for yaw and roll to VOR asymmetries.

Analysis of Visual and Vestibular Information on Motion Sickness in Flight Simulation

Virtual reality (VR) is in its nascent technological advancement and market diffusion stages. Interestingly, the scientific exploration concerning the impact of non-isometric mapping disparities within visual–vestibular stimuli on motion sickness remains deficient. This investigation focuses on scrutinizing the visual–vestibular implications for motion sickness within the context of flight simulation. The developed motion platform, offering specific pitch and roll ranges of ±16 and ±17 degrees, respectively, was employed to induce varying ratios of simulated visual–vestibular cues. Involving a cohort of five participants, the study exposed them to two prevalent simulated mission profiles, subsequently assessing their motion sickness symptoms. Sixty responses were analyzed using the subjective assessment of the Simulator Sickness Questionnaire (SSQ). The findings reveal a reduction in cybersickness severity with congruent visual–vestibular stimuli in proportion to the variance observed among visual–vestibular coupling ratios. A comparative analysis of SSQ sub-categories demonstrates that disorientation holds the most significance in the hierarchy of motion sickness contributors, followed by oculomotor discomfort, with nausea manifesting as the least influential. This study can lead to situation awareness analysis by integrating VR-based flight-simulation setups in the formal training of pilots and UAV operators.

History and Evolution of the Tuning Fork.

This paper is a summary of the evolution of the tuning fork, a crucial part of the cranial nerves and auditory examination. The tuning fork is a two-pronged fork that resonates at a specific pitch when struck against a surface and has been proven to be incredibly useful in diagnosing and detecting hearing disorders. The tuning fork, an unassuming device in modern medicine, traces its origins back to an era when scientific understanding and medical diagnostics were in their nascent stages. Since its inception, this unpretentious instrument has played a pivotal role in the hands of healthcare practitioners, aiding in the diagnosis and assessment of various medical conditions. This paper embarks on a captivating journey through time to explore the origin, evolution, and significant milestones in the development of the tuning fork. From the first suggestion of differentiating hearing disorders to present-day tuning forks, this paper maps the different stages that the tuning fork has gone throughand how its use has changed over time. Along the way, we will discover how the tuning fork has harmonized with music, medicine, and various scientific pursuits, enriching our understanding of sound and resonance while leaving an indelible mark on the course of human history.Delving into the historical context of its creation, this review uncovers the ingenious minds that birthed this innovative device and the pivotal moments that brought it to the forefront of human endeavors.

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.

Designing Composite Adaptive Propeller Blades with Passive Bend-Twist Deformation for Periodic-Load Variations Using Multiple Design Concepts.

Four plausible design concepts are applied together to investigate composite bend-twist propeller-blade designs that show high twisting per bending deflection. The design concepts are first explained on a simplified blade structure with limited unique geometric features to determine generalized principles for applying the considered design concepts. Then, the design concepts are applied to another propeller-blade geometry to obtain a bend-twist propeller-blade design that achieves a specific pitch change under an operational loading condition with a significant periodic-load variation. The final composite propeller design shows several times more bend-twist efficiency than other published bend-twist designs and shows a desirable pitch change during the periodic-load variation when loaded with a one-way fluid-structure-interaction-derived load case. The high pitch change suggests that the design would mitigate undesirable blade effects caused by load variations on the propeller during operation.

How can coaches and players tell the outcome of a pitch in a baseball game based on observed data?

Machine learning and the development of artificial intelligence continues to grow at a rapid pace with the age of technology and computer science jobs growing in demand. With this development the use of predictive technology becomes more realistic to make systems more efficient. For example, in the future of the medical field, a software program may diagnose patients given an input of symptoms and previous health issues more effectively than even humans can.
 Sports are an area with vast possibilities of outcomes, meaning a lot of predictions to be made in all sorts of sports. Humans don’t have the analytical ability to examine every aspect of each player to predict the next situation in a sports game. For example in baseball and softball, there are thousands of possible scenarios that can occur from a singular pitch. 
 How can coaches and players tell the outcome of a pitch based on observed data?
 A simple machine learning predictive model using a technique called gradient descent takes features and examples as input in order to predict one of a couple possible outcomes for a specific pitch with its various features. Results show that upon running such programs numerous times with different iterations the model actually grows stronger in accuracy.

FEATURES OF STUDYING THE EDUCATIONAL DISCIPLINE “INSTRUMENTAL SCIENCE AND METHODOLOGY OF WORKING WITH A CHILDREN’S MUSIC GROUP”: EXPERIENCE AT AN INSTITUTION OF HIGHER EDUCATION

Attention is focused on the importance of improving the quality of music teacher training by achieving the necessary competencies related to music-making technologies on Ukrainian folk instruments in the process of conducting music lessons in secondary schools, managing children's instrumental ensembles in out-of-school education institutions. Work experience while teaching the course «Instrumental science and methods of working with a children's music group» at TNPU is highlighted. The basic conditions that affect the development and process of formation of professional skills and skills of playing in an instrumental ensemble among students, as well as the management of a children's musical group based on mastering the methods of working with a homogeneous and mixed composition of folk traditional instruments of a children's instrumental ensemble, didactic principles and knowledge of performance, are analyzed on such instruments. The process of preparing a future music teacher for the organization and implementation of collective performance instrumental and creative activity of schoolchildren in the conditions of classroom, extracurricular and extracurricular work, the form of conducting rehearsal work with an ensemble of folk instruments in extracurricular time, which involve the student writing a score for the instrumental accompaniment of a vocal work from children's music, is characterized School repertoire and its gradual voicing by the instrumental composition of the academic group. Examples of the use of rhythmic improvisation, the technology of mastering percussion instruments without a specific pitch, the chromatic soprano flute in C major in musical art lessons, and playing music on other traditional folk instruments during classes in an instrumental ensemble are given.

Dots, Versification and Grammar

Abstract The Syriac gospel of Matthew is divided into sentences by means of pausal accent dots, both single clause sentences and complex sentences. This article explores the relationship between these pausal accent dots and verse division, comparing the Syriac dotting system with Greek punctuation marks and Hebrew accents. All three traditions divide the text into larger and smaller sections. In the Hebrew Bible the smaller sections are often classified as verses that are further subdivided through cantillation marks, typically called accents. This article explains why the Syriac dots, also called accents, have a fundamentally different function than the Hebrew accents. It also explores the similarities between the Syriac dots and the Greek punctuation marks. The conclusion is that the “verse” is not a concept that can easily be applied to Syriac Bible manuscripts. Instead, the Syriac dots indicate different types of boundary tones, pauses associated with a specific pitch contour.

Time dependence of the dominant mechanisms of self-propelled droplets by Leidenfrost phenomenon on Zn plate surfaces with and without ZnO nanorods

For an earlier study, using Zn plates with a specific pitch and height, we analyzed the self-propulsion of water droplets caused by the Leidenfrost phenomenon. The results demonstrated the existence of two modes: volume expansion (partial contact mode), which accompanies nucleate boiling; and gravity (gravity mode), which water droplets receive. The dominant mode depends on the temperature. The findings also suggested that proper arrangement of ZnO nanorods onto the ratchet structure might provide synergistic effects between the two modes. Continuing from that earlier study, we analyzed water droplets that were self-propelled by the Leidenfrost phenomenon on Zn plates with double the height and double the pitch of the ratchet structures. Similarly to the structure studied earlier, the self-propulsive behavior of water droplets on these samples was produced by partial contact mode and gravity mode. Furthermore, when the time change of the dominant propulsive force was examined along with data of the earlier report, the high propulsive force found mainly in the partial contact mode at the initial stage of self-propulsion tended to shift to the gravity mode over time. The initial high propulsion duration was also confirmed as becoming shorter as the sample temperature rises. This temperature dependence is regarded as related to the time dependence of the vapor film formation process with the temperature rise of water droplets. The time change of the dominant propulsive force was clarified as dependent on the ratchet structure and surface modification by ZnO nanorods. These facts and related findings demonstrated that the self-propulsion of water droplets attributable to the Leidenfrost phenomenon is controllable by the solid surface design.

Effects of phonological and talker familiarity on second language lexical development

AbstractPrevious research has shown that second language (L2) learners of Mandarin learn new words more easily if the new word is homophonous with a word they already know (Liu and Wiener, 2020). That research involved word learning in which speech was produced by a single-talker with a specific pitch range. The present study examines whether the observed tonal homophone advantage is dependent on familiarity with the talker. Adult learners of Mandarin Chinese as an L2 were taught 20 new tonal words for three consecutive days. To manipulate phonological familiarity, 10 words had homophones already known to the learners and 10 words did not. To manipulate talker familiarity, participants were trained on a single talker but tested on 16 new talkers or trained and tested on 16 (multi)-talkers. Daily testing involved a 4-alternative-force-choice task. Both groups showed increased accuracy and faster response times on Day 2 compared to Day 1, but this learning was independent of homophone status or talker group. No other effects were found. These results suggest that the tonal homophone advantage in L2 word learning observed byLiu and Wiener (2020)may have been partially driven by an exceptionally high level of talker familiarity, since that study used a single speaker both for training and testing.

Precise Underwater Gliders Pitch Control with the Presence of the Pycnocline

Glider-based mobile currents observations are gaining increasing research attention. However, the quality of such observations is directly related to the pitch accuracy of the glider. As a buoyancy-driven robot, the glider will be strongly disturbed during the passage through the pycnocline. The pycnocline refers to the oceanic phenomenon where the density of the seawater changes abruptly with respect to depth. The presence of the pycnocline influences the pitch of the glider and consequently affects the quality of the observed currents data. In this work, we propose an actuator constrained active disturbance rejection controller (ACADRC) to improve the accuracy of the pitch angle control when gliders move across the pycnocline. For this purpose, the dynamical model of the glider is first derived. Then, the longitudinal plane motion model of the glider considering the density variation is analyzed. Based on that, we discuss three typical types of pycnocline encountered during glider profiling, which are the pycnocline, the inverted pycnocline and the multiple pycnocline. To alleviate the low accuracy of bang-bang control and proportion integration differentiation control, and furthermore, to mitigate the disturbance of pitch by sudden density changes, we propose the actuator constrained active disturbance rejection controller in conjunction with specific glider pitch actuator hardware constraints. Simulation results show that the proposed method has significant improvement in pitch control accuracy over the comparison methods.

Perceptions of Vocal Performance Impairment in Singers with and without Hearing Loss

It is well understood that hearing plays an important role in accurate vocal production. Singers in particular rely on auditory cues and auditory feedback to reproduce specific pitch contours. Therefore, even mild hearing loss may have a detrimental effect on a singer's ability to perform. This study investigates the effect of hearing loss on self-reported vocal production in singers, specifically in the domains of pitch matching, pitch maintenance, vowel production, and dynamic control as well as the effect of hearing loss on vocal handicap. An 18-item electronic self-report survey was distributed to the members of the National Association of Teachers of Singing and to the Voice Foundation. Data collected included demographics, the Singing Voice Handicap Index-10 (SVHI-10), and a series of closed and open-ended questions. Demographic variables, variables related to the SVHI-10, and variables related to the newly introduced survey were included in a hierarchical regression analysis to determine significant relationships. Among 206 eligible participants, 37 individuals reported a voice problem, 58 reported hearing loss, and 19 reported concurrent hearing loss and a voice problem. Among males, there were no significant differences between hearing impaired and normal hearing singers in reported pitch matching, pitch maintenance, dynamic control, and vowel matching when those with voice problems were excluded and included. However, in females, when singers with voice problems were excluded, there was a significant difference between hearing impaired and normal hearing singers in pitch matching (P=0.38). Additionally, when singers with voice problems were included in the female subset, significant differences emerged between the hearing impaired and normal hearing singers in areas of pitch matching (P=0.01) and vowel matching (P=0.02). Further, controlling for gender, when excluding voice problems, there was a significant difference between the SVHI-10 scores of normal hearing (mean=9.03) and hearing impaired participants (mean=11.30, P=0.02). This difference continued to be significant when including those with voice problems (normal hearing mean=9.97, hearing impaired mean=14.1, P <0.0001). Additionally, individuals with hearing impairments were more likely to report higher perceived vocal handicap scores as reflected on the SVHI-10 than normal hearing respondents (P=0.002). Other factors associated with higher likelihood of SVHI-10 score include older age (P=0.008), having a voice problem (P <0.0001), and being paid to sing within the past six months (P=0.001). When controlling for voice problems, singers with hearing impairments subjectively did not perceive that they performed less accurately on pitch matching, pitch maintenance, dynamic control, and vowel matching, yet they scored higher on the SVHI-10 indicating vocal handicap. Further study is needed to characterize the relationship between perceived and measured vocal accuracy in singers with hearing loss.

Effect of heat transfer area distribution on frosting performance of refrigerator evaporator

The present study investigates the effect of the distribution of available heat transfer area on the thermohydraulic behavior of a typical fin-and-tube type evaporator used in a domestic frost-free refrigerator. Previous studies in the literature have not explored the effect of the number of fin rows and fin pitch distribution across the fin rows on the performance of fan-supplied evaporator geometries under frosting. The present study attempts to address this by developing a thermohydraulic model of the evaporator to predict the heat transfer rate, pressure drop and frost formation. A distributed evaporator model is developed by dividing the evaporator into individual control volumes and the balance equations are applied along with a suitable semi-empirical frost growth model to predict the rate of frost formation. Experiments were performed in a purpose-built test facility to validate the numerical model. The developed model is employed to compare different heat exchanger geometries with a constant area but varying in total fin rows and fin pitch distribution. Results show that distributing the available heat transfer area among a higher number of fin rows results in longer successive defrost intervals. However, the evaporator occupies more volume. For a given heat transfer area and fin rows, longer operating time can be achieved by selecting fin pitches that provide uniform blockage ratio across the fin rows. It is observed that for a specific fin pitch at the leading row, reducing the fin pitch linearly across the fin rows resulted in uniform blockage ratio across the fin rows.