Steady Pitch Research Articles

Tonal intelligibility within a paragraph

Abstract This study considers the performance of tone pronunciation and morpheme intelligibility by L2 Polish Mandarin learners. A mixed-effects ordinal regression model and Tukey’s HSD multiple test were used to examine the start-point, end-point, of syllables as a means of assessing their intelligibility by L2 Polish learners regarding the tones with the sequence T0, T1, T2, T4 > T3.and T0, T1> T2, T4 > T3, respectively. Students’ tone pronunciation at different stages of learning was compared, i.e. first at less than A1 level of proficiency and then after achieving an A2 level of proficiency according to the Common European Framework of Reference for Languages (CEFR), with the interval of a 22-week intensive Chinese class. The results suggest that in the case of the steady pitch produced for T0 and T1, L2 Polish learners found it easy to control the vibration speed of the vocal folds over two stages. Additionally, progress in successfully producing T4 was exhibited with improving control over the individual tonal register span, implying that competent tonal production develops with time. It remains unclear whether the reason why the low-range T3 is acquired last is down to the habitually high pitched range of spoken Polish, or a more universally observable phenomenon where T3 is liable to be confused with other tones in production.

Effects of pitch angle on a near free surface underwater vehicle

Simulations of an underwater vehicle were conducted to investigate the effects of steady pitch angle, Froude number, and submergence depth. A shallow submerged (D* = 1.1) to a deeply submerged (D* = 6.6) SUBOFF was investigated over a range of steady pitch angles and Froude numbers. Results show that proximity to the free surface causes increased resistance, heave and pitch moment and that free surface effects diminish rapidly with increased submergence depth. Even though D* = 3.3 is typically quoted as being the deeply submerged threshold, free surface effects can still be observed especially at large pitch angles. At pitch angle, asymmetry can be seen between the pressure distribution of the upper and lower surfaces of the SUBOFF, with a phase shift of the hydrodynamic forces and moments. At smaller pitch angles, the changes in hydrodynamic forces and moments stay relatively linear at an offset from zero degrees. At larger pitch angles, the hydrodynamic forces and moments become non-linear due to crossflow separation and air entrainment over the bow/stern. Additionally, the potential of the stern planes to cope with free surface effects were investigated, showing the safety threshold with respect to Froude number, submergence depth, and hull pitch angle.

High-Fidelity Aeromechanical Analysis of Coaxial Mars Helicopter

A high-fidelity coupled computational fluid dynamics and comprehensive analysis solver is developed for helicopter flight on Mars. The objectives are accurate prediction of flight loads and fundamental understanding of Martian aeromechanics. Performance, structural loads, pitch link loads, rotor wake, and interrotor blade separation are studied for hingeless and flap articulated coaxial rotors. In the absence of any validation data, pressure chamber tests are carried out at Mars-like conditions on a single rotor in hover. The data provided an elementary assessment of rotor behavior and a baseline for model validation. Predictions of the high-fidelity solver are also compared with a lower-fidelity lifting-line comprehensive analysis. It is generally concluded that lower-fidelity tools are not adequate for capturing the complex flow phenomena encountered on Mars. A motion and loads comparison of two fundamental hub types revealed that 1) an articulated hub has similar interrotor blade separation as hingeless on Mars, 2) a hingeless hub experiences only marginally higher (6–7%) flap bending moments, and 3) an articulated hub can lower steady pitch link loads (by an order of magnitude) at a marginal expense of oscillatory loads, 15% higher.

Is it OK to renege on an offer letter?

When you come to an intersection with a four-way stop, what are the rules of the road where you live? Some drivers’ manuals do not have clear-cut rules but note that common courtesy requires the initial driver to go first. In Wyoming, the manual states in capital letters, “If in doubt, yield to the driver on your right” and “Remember to never insist on the right of way at the risk of a crash.” If such an interaction is so simple yet has so many differing approaches, what hope is there to establish good rules and norms around more difficult questions, like employment? Each year, I host a discussion forum on my blog for those who are seeking tenured academic employment in chemistry. Readers post more than 1,000 comments as job openings begin to show up in June and reach a steady pitch in September and October. These comments include

Intonation trajectories within tones in unaccompanied soprano, alto, tenor, bass quartet singing.

Unlike fixed-pitch instruments, the voice requires careful regulation during each note in order to maintain a steady pitch. Previous studies have investigated aspects of singing performance such as intonation accuracy and pitch drift, treating pitch as fixed within notes, while the pitch trajectory within notes has hardly been investigated. The aim of this paper is to study pitch variation within vocal notes and ascertain what factors influence the various parts of a note. The authors recorded five soprano, alto, tenor, bass quartets singing two pieces of music in three different listening conditions, according to whether the singers can hear the other participants or not. After analysing all of the individual notes and extracting pitch over time, the authors observed the following regularities: (1) There are transient parts of approximately 120 ms duration at both the beginning and end of a note, where the pitch varies rapidly; (2) the shapes of transient parts differ significantly according to the adjacent pitch, although all singers tend to have a descending transient at the end of a note; (3) the trajectory shapes of female singers differ from those of male singers at the beginnings of notes; (4) between vocal parts, there is a tendency to expand harmonic intervals (by about 8 cents between adjacent voices); (5) the listening condition had no significant effect on within-note pitch trajectories.

Inverse speed analysis and low speed control of underwater vehicle

Inverse speed is a reversible maneuver. It is a characteristic of underwater vehicle at low speed. Maneuverability in the vertical plane at a speed lower than inverse speed is different from one at higher speed. In the process of underwater working for observation, AUV’s cruise speed is always low. Therefore, the research on inverse speed is important to AUV’s maneuverability. The mechanism of inverse speed was analyzed, and then the steady pitching equation was derived. The parameter expression of track angle in vertical plane was deduced. Furthermore, the formula to calculate the inverse speed was obtained. The typical inverse speed phenomenon of the flat body and the revolving body was analyzed. Then the conclusion depicts that, for a particular AUV with flat body, its inverse speed is lower than that of revolving body. After all the calculation and the analysis, a series of special experiments of inverse speed were carried out in the simulation program, in the tank and in the sea trial.

Modelling and characteristics analysis of the pitch system of large scale wind turbines

The individual pitch drive system of large-scale wind turbines was analysed in this article. In this pitch system, the induction motor, three-stage planetary gearbox, and motor vector control were adopted. In order to investigate the system dynamic behaviour, its non-linear dynamical model was established, mainly including three parts: induction motor model in d— q frame, dynamic model of three-stage planetary gears, and transmission shaft model. The dynamic responses of gearbox—blade subsystem and motor—gearbox—blade system were analysed in detail, respectively. Then, the pitch system control model was established in which rotor flux field-oriented vector control and double close-loop servo control with speed and position feedback were employed. In simulation, the algorithm TR-BDF2 was adopted to solve the dynamic equations. The research results show that the deviation between the pitch angle and its command value is very small in steady state, pitch speed and acceleration fluctuations appear when impact effect is produced due to gear backlash, and the different blade may have different variable pitch speed and acceleration in some pitch region. The research results give a reasonable explanation for running mechanism of the individual pitch system and are helpful for optimization design and control for the individual blade pitch control system used in large-scale wind turbines.

Age effects of pitch-shifted auditory feedback on reflexive and volitional voice F0 control

Research on voice fundamental frequency (F0) control suggests that when making a voluntary vocal response to a pitch change in voice auditory feedback, the pitch-shift reflex typically occurs before the volitional response is initiated. The current study examined the effects of aging on reflexive and volitional voice F0 responses to pitch-shifted auditory feedback. Thirty participants (age range 19 to 78 years) repeatedly sustained an /u/ vocalization at a steady pitch and loudness while listening to their voice fed backed over headphones. Once per vocalization, feedback pitch was randomly shifted upward or downward for 100 milliseconds and 20 or 100 cents. In the Sustain condition, participants attempted to ignore the pitch change in auditory feedback voice. In the Follow condition, participants immediately changed their pitch in the same direction as the auditory pitch shift they heard. Preliminary results from thirteen participants indicate that there appears to be no effect of aging on the first F0 responses for both magnitude and latency. Voluntary voice F0 changes were delayed in older participants compared to younger participants as expected due to age-related general slowing. Results broaden our understanding of typical reflexive and volitional voice control capabilities across the age span.

Rotary aerodynamic derivatives in the asymptotic theory of a high-aspect-ratio wing

The linear problem of inviscid incompressible flow around a high-aspect-ratio wing at an angle of attack and in the presence of steady pitching and rolling rotation is considered. The main integral equation of the problem is reduced to a sequence of one-dimensional integral equations without use of the matched asymptotic expansions method. The first few terms of the series for the circulation distribution over the wing surface are calculated. For an elliptic high-aspect-ratio wing the corresponding aerodynamic forces are calculated. The derivatives of the aerodynamic coefficients of the wing with respect to the angle of attack and the angular velocities are determined. The asymptotic expressions obtained are compared with the results of numerical calculations of the corresponding derivatives using the discrete vortex method.

My voice looks like that? Analysis and synthesis of vowel sounds in a PC-based lab

How is it that we can recognize familiar vowel sounds regardless of who is speaking? How does my voice compare to your voice? The acoustics laboratory exercise described here appeals to our natural curiosity about everyday phenomena and about ourselves. In the first part, students use a PC equipped with a built‐in microphone and easy‐to‐use sound analysis software to record themselves ‘‘singing’’ a variety of vowel sounds, each with the same steady pitch. With the spectrum of each vowel displayed, students initially confirm the presence of the harmonic series and identify the fundamental frequency, reinforcing the association of these characteristics with the pitch of the vowel sound. Working in small groups, students then investigate a correlation between the specific vowel and its spectrum envelope. By comparing the spectra of similar vowels sung by different students, as well as the spectra of different vowels, students learn to recognize formants within the spectrum. In the second part, students apply their newfound understanding of the role of formants by attempting to synthesize a vowel sound by adding harmonic components. The sound synthesis is also done with commonly available PC software.

Influence of Steady Pitch Rate on 2-D Airfoil Aerodynamic Characteristics at Incidence

I N various dynamic problems it is important to know the constituent parts of aerodynamic loads due to pitch rotation. However, the attention given to this question at higher angles of attack with flow separation has been very low. Sometimes the problem of modeling aerodynamic loads due to steady pitch rotation is mixed up with modeling aerodynamic loads due to incidence variation. Some discussions of the question can be found in [1]. These are really two distinct tasks. The first task is a steady one. It is possible to imagine motions with a constant angle of attack and various pitch rates. These are circular orbital motions with various radii. On the other hand a translational motion with zero pitch rate and varying incidence could exist also. In the first case the circulation is constant. In the second case a time-dependent vortex wake exists behind the body. The present work is devoted to some estimations using thin airfoil theory of pitch rate effects on a 2-D airfoil with flow separation at high constant angles of attack. For low angles of attack the influence of steady pitch rate on airfoil loads was investigated, for example, in [2]. For the case of zero pitch rate the effects of flow separation on aerodynamic loads was investigated using the linearized thin airfoil theory in [3]. This approach was now applied to estimations of pitch rate effects on a 2D airfoil with flow separation at high constant angles of attack. For comparison, numerical estimations from the well-known XFOIL code [4] were used. The effect of steady pitch rate is simulated using the approximate technique of curved models [5] (pitch rate induced curvature).

Envelope Following Responses to Natural Vowels

Envelope following responses to natural vowels were recorded in 10 normal hearing people. Responses were recorded to individual vowels (/ɑ/, /i/, /u/) with a relatively steady pitch, to /∧/ with a variable and steady pitch, and to a multivowel stimulus (/∧ui/) with a steady pitch. Responses were analyzed using a Fourier analyzer, so that recorded responses could follow the changes in the pitch. Significant responses were detected for all subjects to /ɑ/, /i/ and /u/ with the time required to detect a significant response ranging from 6 to 66 s (average time: 19 s). Responses to /∧/ and /∧ui/ were detected in all subjects, but took longer to demonstrate (average time: 73 s). These results support the use of a Fourier analyzer to measure envelope following responses to natural speech.

Universal acoustic flame detection for modified supercritial fluid chromatography

A novel detector, based on the frequency of acoustic emissions from an oscillating premixed hydrogen/oxygen flame, has been characterized for use in supercritical-fluid chromatography (SFC). When an organic analyte is introduced, the steady pitch of the acoustic flame detector (AFD) increases proportionally to the carbon content of the molecule. Using standard hydrocarbon analytes, the SFC–AFD system provided a linear response over about 3 orders of magnitude with a detection limit ( S/ σ = 3) of 18 ng of carbon per second. The detector sensitivity was uniform for all analytes and did not change when using either pure or methanol modified supercritical-carbon dioxide (SC-CO 2) as a mobile phase. While a stable baseline could be obtained for a variety of constant conditions, density gradients did cause it to shift due to the changing flow rate encountered when using a passive restrictor. While these changes were small for a pure SC-CO 2 mobile phase, they were larger when using a methanol modifier. Qualitatively, the AFD response compared well to a flame ionization detector (FID). Overall, the results indicate that the AFD may be a useful, inexpensive universal detector for SFC applications that require organic modifiers and are unable to use an FID.

Aerodynamic characteristics of a 2-box girder section adaptable for a super-long span suspension bridge

According to the previous investigation on the suspension bridge with a 2-box and 1-box combined girder, which is newly developed to apply to the super-long span bridge having a main span of 2500 m or more, it is indicated that unbearable large torsional displacement induced in the high wind velocity and decreased flutter stability are the problems to be solved. This paper deals with the investigation of an improvement of steady pitching moment characteristics on the girder cross section to decrease the torsional displacement under wind loads, and also an improvement of flutter stability. As a result of investigation on the 6-lane-type girder, it is found that the steady pitching moment characteristics and flutter stability can be improved by attaching rails for an inspection cab to the bottom of fairing and by attaching vertical plates to the lower flange of the girder. Furthermore, a study is conducted on the subject of a 4-lane-type girder having similar cross section to the 6-lane-type girder section.

Early pitch-shift response is active in both steady and dynamic voice pitch control.

When air conducted auditory feedback pitch is experimentally shifted upward or downward during steady phonation, voice pitch changes in response. The first pitch change is an automatic deflection opposite in direction to the feedback shift. It appears to help stabilize voice pitch by counteracting unintended changes. But what happens during an intended pitch change? If the purpose of the first pitch-shift response is to stabilize voice pitch around a fixed target, it should be suppressed during voluntary pitch changes. Alternatively, if the pitch-shift response is a general process of voice control it should be modified during intended pitch changes to bring production in line with the desired output. Auditory feedback pitch was shifted during steady pitch and upward glissando vocalizations by thirty trained singers. Contrary to the "steady-specific" hypothesis, pitch-shift responses occurred during dynamic pitch vocalizations. Responses were comparable in direction, peak time, and slope, but had significantly longer latency and smaller magnitude than responses elicited during steady note phonation. Results indicate that the early pitch-shift response is a general component of voice control that serves to automatically bring phonation pitch into agreement with an intended target, whether that target is constant or changing in time.

The internal auditory clock: what can evoked potentials reveal about the analysis of temporal sound patterns, and abnormal states of consciousness?

Whereas in vision a large amount of information may in theory be extracted from instantaneous images, sound exists only in its temporal extent, and most of its information is contained in the pattern of changes over time. The “echoic memory” is a pre-attentive auditory sensory store in which sounds are apparently retained in full temporal detail for a period of a few seconds. From the long-latency auditory evoked potentials to spectro-temporal modulation of complex harmonic tones, at least two automatic sound analysis processes can be identified whose time constants suggest participation of the echoic memory. When a steady tone changes its pitch or timbre, “change-type” CP1, CN1 and CP2 potentials are maximally recorded near the vertex. These potentials appear to reflect a process concerned with the distribution of sound energy across the frequency spectrum. When, on the other hand, changes occur in the temporal pattern of tones (in which individual pitch changes are occurring at a rate sufficiently rapid for the C-potentials to be refractory), a large mismatch negativity (or MN1) and following positivity (MP2) are generated. The amplitude of these potentials is influenced by the degree of regularity of the pattern, larger responses being generated to a “deviant” tone when the pitch and time of occurrence of the “standards” are fully specified by the preceding pattern. At the sudden cessation of changes, on resumption of a steady pitch, a mismatch response is generated whose latency is determined with high precision (in the order of a few milliseconds) by the anticipated time of the next change, which did not in fact occur. The mismatch process, therefore, functions as a spectro-temporal auditory pattern analyser, whose consequences are manifested each time the pattern changes. Since calibration of the passage of time is essential for all conscious and subconscious behaviour, is it possible that some states of unconsciousness may be directly due to disruption of internal “clocks”? Abnormal mismatch potentials may provide a manifestation of a disordered auditory time-sense, sometimes being abolished in comatose patients while the C-potentials and similar responses to the onset of tones are preserved. Both C- and M-potentials were usually found to be preserved, however, in patients who had emerged from coma and were capable of discriminating sounds. Substantially intact responses were also recorded from three patients who were functionally in a “vegetative” state. The C- and M-potentials were once again dissociated in a group of patients with multiple sclerosis, only the mismatch potentials being found to be significantly delayed. This subclinical impairment of a memory-based process responsible for the detection of change in temporal sound patterns may be related to defects in other memory domains such as working memory.

Auditory evoked potentials to spectro-temporal modulation of complex tones in normal subjects and patients with severe brain injury.

In order to assess higher auditory processing capabilities, long-latency auditory evoked potentials (AEPs) were recorded to synthesized musical instrument tones in 22 post-comatose patients with severe brain injury causing variably attenuated behavioural responsiveness. On the basis of normative studies, three different types of spectro-temporal modulation were employed. When a continuous 'clarinet' tone changes pitch once every few seconds, N1/P2 potentials are evoked at latencies of approximately 90 and 180 ms, respectively. Their distribution in the fronto-central region is consistent with generators in the supratemporal cortex of both hemispheres. When the pitch is modulated at a much faster rate ( approximately 16 changes/s), responses to each change are virtually abolished but potentials with similar distribution are still elicited by changing the timbre (e.g. 'clarinet' to 'oboe') every few seconds. These responses appear to represent the cortical processes concerned with spectral pattern analysis and the grouping of frequency components to form sound 'objects'. Following a period of 16/s oscillation between two pitches, a more anteriorly distributed negativity is evoked on resumption of a steady pitch. Various lines of evidence suggest that this is probably equivalent to the 'mismatch negativity' (MMN), reflecting a pre-perceptual, memory-based process for detection of change in spectro-temporal sound patterns. This method requires no off-line subtraction of AEPs evoked by the onset of a tone, and the MMN is produced rapidly and robustly with considerably larger amplitude (usually >5 microV) than that to discontinuous pure tones. In the brain-injured patients, the presence of AEPs to two or more complex tone stimuli (in the combined assessment of two authors who were 'blind' to the clinical and behavioural data) was significantly associated with the demonstrable possession of discriminative hearing (the ability to respond differentially to verbal commands, in the assessment of a further author who was blind to the AEP findings). Behavioural and electrophysiological findings were in accordance in 18/22 patients, but no AEPs could be recorded in two patients who had clear behavioural evidence of discriminative hearing. The absence of long-latency AEPs should not, therefore, be considered indicative of complete functional deafness. Conversely, AEPs were substantially preserved in two patients without behavioural evidence of discriminative hearing. Although not necessarily indicative of conscious 'awareness', such AEP preservation might help to identify sentient patients who are prevented by severe motor disability from communicating their perception.

The influence of pitch contour on vowel discrimination in infants

Because the harmonics are farther apart in high- than in low-pitched vowels, it was predicted that it should be difficult to extract the frequencies of the formant resonances, and therefore, to discriminate high-pitched vowels. Infant-directed speech is very high in pitch, yet studies showing that young infants can discriminate vowels have used low-pitched male voices. The present study showed that 6-month olds were able to discriminate /i/ and /I/ when the pitch was 240 Hz, but were unable to do so when the pitch was 340 Hz, demonstrating that the high pitch of infant-directed speech indeed impedes vowel discrimination. How, then, do infants learn vowel discrimination? The answer may lie with the large pitch contours that are also characteristic of infant-directed speech. Because the harmonic structure follows the frequency of the fundamental, but the formant structure remains relatively constant across frequency shifts, a second prediction was made: discrimination should be better for vowels containing pitch contours than for those with steady pitch. This is exactly what was found. The addition of a downward pitch contour at both high (440–340 Hz) and low (240–140 Hz) pitches significantly improved infants discrimination of /i/ and /I/. [Research supported by NSERC.]

Cortical processing of complex tone stimuli: mismatch negativity at the end of a period of rapid pitch modulation

In this study, synthesised instrumental tones were used to examine human auditory cortical processes engaged at the end of a period of rapid pitch modulation. It was previously [S.J. Jones, O. Longe, M. Vaz Pato, Auditory evoked potentials to abrupt pitch and timbre change of complex tones: electrophysiological evidence of `streaming'?, Electroencephalogr. Clin. Neurophysiol., 108 (1998) 131–142] suggested that the `change-N1' produced by infrequent changes in pitch or timbre of a continuous complex tone represents the activity of a neuronal population topographically distinct from that responsible for the `onset-N1' at the beginning of the tone. In the present study a superficially similar negativity was produced when the tone came to rest on a steady pitch after a period of rapid (8–16 changes/s) modulation; its scalp maximum was anterior to that of the two previously identified potentials but similar to that of the mismatch negativity elicited by discontinuous tones. By varying the modulation rate the latency was shown to be relatively constant with respect to the time the next pitch change was expected but failed to occur. The largest responses averaging c. 7 μV were evoked at the end of modulation sequences which were both rhythmic and repetitive, but a potential was still produced when there was no rhythmic pattern or repetition of individual notes. This response to non-occurrence of an expected but not necessarily specified change implies an automatic process for comparing the incoming sound with an extrapolated template of the preceding pattern in which timing as well as pitch information is accurately represented. We suggest this technique offers a robust method for eliciting the mismatch negativity, which may extend the opportunities for electrophysiological investigation of higher auditory processes.

An Investigation of Helicopter Dynamic Coupling Using an Analytical Model

Many attempts have been made in recent years to predict the off-axis response of a helicopter to control inputs, and most have had little success. Since physical insight is limited by the complexity of numerical simulation models, this paper examines the off-axis response problem using an analytical model, with the goal of understanding the mechanics of the coupling. A new induced velocity model is extended to include the effects of wake distortion from pitch rate. It is shown that the inclusion of these results in a significant change in the lateral flap response to a steady pitch rate. The proposed inflow model is coupled with the full rotor/body dynamics, and comparisons are made between the model and flight test data for a UH-60 in hover. Results show that inclusion of induced velocity variations due to shaft rate improves correlation in the pitch response to lateral cycle inputs.