LF Waves Research Articles

The change in Baroreflex Regulation of Heart Rhythm after “Dry” Immersion Appears during Orthostasis, but not Lower Body Negative Pressure Test

The ratio of low-frequency (LF, ~0.1 Hz) waves of RR interval duration (RRI) and systolic blood pressure (SAP) reflects the cardiac baroreflex sensitivity (BRS). Gravitational unloading (GU) may alter BRS during the passive orthostatic test (HUT) and lower body negative pressure (LBNP) test. Both effects cause blood redistribution to the lower body, but HUT is accompanied by greater unloading of sinocarotid baroreceptors than LBNP and activation of the vestibulosympathetic reflex but GU effects on BRS in these tests have not been directly compared previously. In this study we tested the hypothesis that the effect of “dry” immersion (DI, on-ground model of GU) on BRS in the same subjects will be more pronounced during HUT than during LBNP, which causes a comparable decrease in stroke volume. Nine healthy men participated in two test sessions (before and after 7-day DI) consisting of five 3-min HUT (65°) and five 3-min LBNP (–35 mmHg) with averaging the parameters in each test. Wavelet analysis was used to determine the amplitude of the RRI and SAP waves in the range of 0.05–0.13 Hz. The amplitude of LF waves of SAP increased in both tests, after DI - more significantly in HUT. The amplitude of LF RRI waves decreased in the two tests; the degree of decrease did not differ between tests and did not change under the influence of DI. The α-coefficient (the ratio of the amplitudes of RRI and SAP LF waves) decreased equally in the two tests before DI, but after DI, the degree of α-coefficient reduction increased in HUT test but did not change in LBNP test. Thus, the effect of DI on BRS is evident in HUT, but not in LBNP, which may be explained by the more pronounced influence of HUT on the mechanisms of neural control of heart rhythm.

Absolute and Relative Power of LF Waves of Cardiointervalogram in Athletes (Literature Review)

Absolute and Relative Power of LF Waves of Cardiointervalogram in Athletes (Literature Review)

Cerebral blood flow response to cardiorespiratory oscillations in healthy humans

Dynamic cerebral autoregulation (CA) characterizes the cerebral blood flow (CBF) response to abrupt changes in arterial blood pressure (ABP). CA operates at frequencies below 0.15Hz. ABP regulation and probably CA are modified by autonomic nervous activity. We investigated the CBF response and CA dynamics to mild increase in sympathetic activity. Twelve healthy volunteers underwent oscillatory lower body negative pressure (oLBNP), which induced respiratory-related ABP oscillations at an average of 0.22Hz. We recorded blood velocity in the internal carotid artery (ICA) by Doppler ultrasound and ABP. We quantified variability and peak wavelet power of ABP and ICA blood velocity by wavelet analysis at low frequency (LF, 0.05-0.15Hz) and Mayer waves (0.08-0.12Hz), respectively. CA was quantified by calculation of the wavelet synchronization gamma index for the pair ABP-ICA blood velocity in the LF and Mayer wave band. oLBNP increased ABP peak wavelet power at the Mayer wave frequency. At the Mayer wave, ABP peak wavelet power increased by >70% from rest to oLBNP (p<0.05), while ICA blood flow velocity peak wavelet power was unchanged, and gamma index increased (from 0.49 to 0.69, p<0.05). At LF, variability in both ABP and ICA blood velocity and gamma index were unchanged from rest to oLBNP. Despite an increased gamma index at Mayer wave, ICA blood flow variability was unchanged during increased ABP variability. The increased synchronization during oLBNP did not cause less stable CBF or less active CA. Sympathetic activation seems to improve the mechanisms of CA.

Состояние вегетативной адаптации у пациентов с хроническим описторхозом

Aim: to assess autonomic regulation by analyzing heart rate variability in patients with chronic opisthorchiasis (CO). Patients and Methods: the study involved 31 patients with CO and 30 healthy volunteers (control group). Clinical parameters of the biliary system and autonomic nervous system were as-sessed in all participants. The Baevsky method of mathematical analysis of heart rhythm was used to study autonomic nervous system functions. Parameters characterizing the activity of various branches of the autonomic nervous system were calculated. The results obtained were processed using the original CORVEG program. Results and Discussion: frequency analysis in patients with CO revealed significant deviations of SD, AMo, and CV in the supine position and EV, MSD, Mo, and AMo in active orthostatic position, thereby illustrating an increase in the effect of the sympathetic branch and a reduction in the effect of the parasympathetic branch of the autonomic nervous system (a decrease in heart rate variability in the CO group). Values of the HF and LF waves were significantly higher in the CO group (p&lt;0.05) in the supine position, thereby illustrating an impairment of humoral regulation and a decrease in the activity of intersystem regulation. Changes in the parameters of heart rate regulation significantly (p&lt;0.05) showed increased sympathetic regulation at rest and orthostasis in CO. Their autonomic homeostasis shifted toward the sympathetic nervous system both at rest and during exercise. Moreover, in some patients (31%), central dysregulation was detected. Autonomic tone and autonomic reactivity in CO were also significantly (p&lt;0.05) shifted toward sympathicotonia and hypersympathicotonia. Conclusion: in CO, deviations at all levels of autonomic regulation were detected, which manifested as increased activity of the sympathetic branch and decreased parasympathetic regulation, vasoreflex and baroreflex mechanisms, and humoral regulation. KEYWORDS: chronic opisthorchiasis, Opisthorchis felineus, autonomic nervous system, parasympathetic nervous system, sympathetic nervous system, heart rate variability, cardiointervalography. FOR CITATION: Plotnikova E.Yu., Karbysheva N.V., Nikonorova M.A., Beskhlebova O.V., Ivanova M.E., Sinkov M.A., Kanner E.V., Kanner I.D. Vegetative adaptation in patients with chronic opisthorchiasis. Russian Medical Inquiry. 2023;7(11):725–732 (in Russ.). DOI: 10.32364/2587- 6821-2023-7-11-4.

Heart rate variability in cross-country skiers with different level of maximum oxygen consumption

AIM: This research aimed to study heart rate variability (HRV) in cross-country skiers with different levels of maximal oxygen consumption (VO2max).&#x0D; MATERIALS AND METHODS: HRV analysis was carried out using the Ecosan-2007 (Medical Computer Systems, Russia) complex in 52 cross-country skiers from the Komi Republic team (candidates for master of sports and master of sports of Russia). The Oxycon Pro ergospirometric system (Erich Jaeger, Germany) was used to calculate VO2max. To identify the HRV patterns in individuals with different levels of VO2max, volunteers were divided into two groups: with VO2max up to 4400 ml/min (n=27) and over 4400 ml/min (n=25). The MannWhitney U-test was used to ascertain whether the differences between groups were statistically significant. A Spearman correlation test was used to analyze the relationship between the VO2max and HRV.&#x0D; RESULTS: Athletes with different levels of VO2max showed significant differences in several HRV indicators as follows: absolute values of LF and VLF waves, the relative value of HF waves, LF/HF, and IC indices. Correlation analysis indicated the presence of a significant negative correlation between the absolute values of VO2max and MxDMn, MxRMn, LF/HF, IC, power of LF, and LF%. VLF waves. Furthermore, a positive correlation was observed between VO2max and HF%. The relative values of the VO2max/kg showed a significant negative correlation with MxRMn, TP, LF, VLF, LF/HF, and IC; and positive with HF%.&#x0D; CONCLUSION: In cross-country skiers, a significant correlation was identified between VO2max and HRV parameters. Compared to Athletes with lower VO2max, those with higher VO2max had a more efficient mode of heart rate regulation.

INDICATORS OF HEART RATE VARIABILITY AT REST AND DURING AN ORTHOSTATIC CHALLENGE AT DIFFERENT RANGES OF MxDMn VALUE AND THEIR CHANGE IN TRACK AND FIELD ATHLETES IN THE TRAINING PROCESS

The aim of the study is to develop the standards of HRV indexes at rest and during an orthostatic challenge, taking into account different ranges of variability of cardiac intervals (MxDMn) of track and field athletes. The other purpose is to identify the features of changes in the standards in the training process in cases of malfunctions of cardioregulatory systems, sinus node functioning and recovery process, overtraining, and decrease in athletic performance. The authors used the results of individual dynamic express-tests of heart rate variability (HRV) in track and field athletes belonging to different specific training orientations to achieve the goals of the study. Research Methods and Organization. We carried out 1740 dynamic HRV measurements at rest and during an orthostatic challenge. The studies involved 56 track and field athletes (sprinters, middle distance runners and stayers) aged 18 to 29 years, belonging to the 1st adult category, Candidates Master of Sports and Masters of Sports, in different periods of the training process. We carried out HRV measurements in the laboratory of functional research methods of the Institute of physical culture and sports at Udmurt State University, as well as at training camps in the middle mountains (Kyrgyzstan, Kislovodsk) and on the plain (Elabuga). We examined the test subjects at rest in the morning after the previous training day, using the VARICARD 2.51 device and the ISCIM6 and VARICARD MP programs (Ryazan). We recorded cardio intervals of athletes for 5 minutes in lying position and for 6 minutes in standing position. We applied HRV measurements to one or four athletes simultaneously using the ISCIM6 and VARICARD MP programs. Research results. We assigned special emphasis to the assessment of changes in the variational range of cardiointervals (MxDMn) reflecting the state of cardiac regulation and the sinus node functioning during dynamic HRV studies in the training process of each runner. We identified seven MxDMn variation ranges from &lt;150ms to &gt;650ms. We revealed that each MxDMn variation range corresponds to a certain prevailing type of regulation. We demonstrated that frequent shifts of the MxDMn ranges from one level to another in the training process of runners indicate instability of cardiac regulation. We elaborated standards for the variational range of cardiointervals (MxDMn), taking into account the predominance of the HF and LF power in the HRV power spectrum for runners with different specific training orientations. We found that respiratory (HF) or vasomotor waves (LF) could prevail within the same MxDMn variation ranges, which points to a different autonomic balance. We revealed that at rest, the variational range of cardiointervals (MxDMn) depends more on the state of cardiac regulation and the sinus node functioning and less on the specifics of running. We often detected paradoxical reactions to an orthostatic challenge at low or extremely high MxDMn values in the overtrained runners. We determined that runners of any specific training orientation could increase their fitness, adaptive and reserve capabilities only in the context of the optimal regulation state, stable favorable ranges of MxDMn values, and the absence of paradoxical reactions to an orthostatic challenge. The paper contains tables with standard HRV indicators for different MxDMn variation ranges and consideration of the predominance of HF and LF waves at rest and during an orthostatic challenge, as well as examples of the results of HRV analysis at rest and during an orthostatic challenge in runners with different MxDMn variation ranges in the training process. Conclusion. The research demonstrated that the use of the HRV analysis method at rest and during an orthostatic challenge, taking into account the standards of MxDMn values in the training process of track and field athletes, is aimed at obtaining the necessary information about the stability of autonomic balance, autonomic reactivity and body reserves that ensure optimal adaptation and recovery processes.

FEATURES OF WEAKLY NONLINEAR WAVE INTERACTION

Regular and stochastic dynamics of three wave interaction and dynamics of cascades of such three wave processes were investigated. It was shown that matrix elements of wave interaction are inversely proportional to square of frequency of LF wave participating in three wave interaction. It was shown, that thresholds of arising of regimes with dynamics chaos are proportional to cube of LF wave. By numerical methods dynamics of cascades of interacting waves was investigated in detail.

Transfer and dissipation of energy during wave group propagation on a gentle beach slope

AbstractThe propagation of bichromatic wave groups over a constant 1:100 beach slope and the influence of the group modulation is presented. The modulation is controlled by varying the group frequency, fg, which is shown to remarkably affect the energy transfer to high and low frequency components. The growth of the high frequency (hf) wave skewness increases when fg decreases. This is explained by nonlinear coupling between the primary frequencies, which results in a larger growth of hf components as fg decreases, causing the hf waves to break earlier. Due to high spatial resolution, wave tracking has provided an accurate measurement of the varying breakpoint. These breaking locations are very well described ( ) by the wave‐height to effective‐depth ratio (γ). However, for any given Iribarren number, this γ is shown to increase with fg. Therefore, a modified Iribarren number is proposed to include the grouping structure, leading to a considerable improvement in reproducing the measured γ‐values. Within the surf zone, the behavior of the Incident Long Wave also depends on the group modulation. For low fg conditions, the lf wave decays only slightly by transferring energy back to the hf wave components. However, for high fg wave conditions, strong dissipation of low frequency (lf) components occurs close to the shoreline associated with lf wave breaking. This mechanism is explained by the growth of the lf wave height, induced partly by the self‐self interaction of fg, and partly by the nonlinear coupling between the primary frequencies and fg.

LABORATORY EXPERIMENTS OF BICHROMATIC WAVE GROUPS PROPAGATION ON A GENTLE SLOPE BEACH PROFILE AND ENERGY TRANSFER TO LOW AND HIGH FREQUENCY COMPONENTS

This work presents a first analysis of experimental data studying the influence of the frequency bandwidth on the&#x0D; propagation of bichromatic wave groups over a constant 1:100 beach slope. The use of a large spatial cross-shore resolution&#x0D; and Bi-Spectral analysis techniques allows the identification of nonlinear energy transfers along the propagation&#x0D; of wave groups. During wave-group shoaling, nonlinear coupling between the primary wave frequencies results in a&#x0D; larger growth of superharmonics for narrow-banded wave conditions, increasing the skewness of the wave and leading&#x0D; to eventual instabilities and earlier high frequency (hf) wave breaking compared to the broad-banded wave condition.&#x0D; Regarding the growth of low frequency (lf) component, the data analysis has shown a larger growth of the incident&#x0D; bound long wave (IBLW) for broad-banded wave conditions. It is generally assumed that the transferred energy from&#x0D; the primary wave components to subharmonics does not affect the short wave energy budget. Here, the opposite is&#x0D; hypothesised, and a larger growth of the IBLW for broad-banded wave conditions is accompanied of a larger reduction&#x0D; of the primary wave components, a reduced growth of hf components and, consequently, a reduction in the growth&#x0D; of hf wave asymmetry during wave group shoaling. Conversely for narrow-banded wave conditions, a reduced IBLW&#x0D; growth is associated with a larger growth of hf wave asymmetry. After hf wave breaking, within the low frequency&#x0D; domain (lf), the IBLW decays slightly for narrow-banded conditions, consistent with a reduction in radiation stress&#x0D; forcing. This involves a nonlinear energy transfer from the wave group frequency back to hf components. The remaining&#x0D; lf energy, Outgoing Free Long Wave (OFLW), reflects back at the shoreline. However, for broad-banded wave&#x0D; conditions, strong dissipation and minimal reflection of lf components occurs close to the shoreline, which might be&#x0D; caused by lf wave breaking.

Euclidean to Minkowski Bethe\u2013Salpeter amplitude and observables

We propose a method to reconstruct the Bethe–Salpeter amplitude in Minkowski space given the Euclidean Bethe–Salpeter amplitude – or alternatively the light-front wave function – as input. The method is based on the numerical inversion of the Nakanishi integral representation and computing the corresponding weight function. This inversion procedure is, in general, rather unstable, and we propose several ways to considerably reduce the instabilities. In terms of the Nakanishi weight function, one can easily compute the BS amplitude, the LF wave function and the electromagnetic form factor. The latter ones are very stable in spite of residual instabilities in the weight function. This procedure allows both, to continue the Euclidean BS solution in the Minkowski space and to obtain a BS amplitude from a LF wave function.

Interaction of ULF waves with different ion species: Pitch angle and phase space density implications

AbstractULF waves can accelerate/decelerate the charged particles including the ring current ions via drift‐bounce resonance, which play an important role in the dynamics of ring current during storm times. This study compares the different behaviors of oxygen ions (10.5–35.1 keV) and protons (0.3–12.3 keV) which simultaneously interact with Pc5 ULF waves observed by Cluster on 3 June 2003. The ULF waves are identified as the fundamental mode oscillations. Both oxygen ions and protons show periodic energy dispersion and pitch angle dispersion signatures, which satisfy the drift‐bounce resonance condition of N=2. The different behaviors of oxygen ions and protons include (1) the resonant energy of oxygen ions is higher than that of protons due to mass difference; (2) the phase space density (PSD) of oxygen ions show relative variations (3.6–6.3) that are much larger than that of protons (&lt;0.4), which indicates a more efficient energy exchange between oxygen ions and ULF waves; (3) the PSD spectra show that oxygen ions are accelerated, while protons are decelerated, which depend on the radial gradient of their PSD; (4) the pitch angle distributions (PADs) of the oxygen ions and protons show negative slope and bidirectional field‐aligned features, respectively, which is related to the preexisting state of ion PADs before the interaction with the ULF waves. In addition, the resonant ions with peak fluxes tracing back to the magnetic equator are always collocated with the accelerating (westward) electric field, which indicate that the ions are mainly accelerated near the magnetic equator and the electric field intensity of ULF waves peaks there.

Electric and magnetic radial diffusion coefficients using the Van Allen probes data

AbstractULF waves are a common occurrence in the inner magnetosphere and they contribute to particle motion, significantly, at times. We used the magnetic and the electric field data from the Electric and Magnetic Field Instrument Suite and Integrated Sciences (EMFISIS) and the Electric Field and Waves instruments (EFW) on board the Van Allen Probes to estimate the ULF wave power in the compressional component of the magnetic field and the azimuthal component of the electric field, respectively. Using L∗, Kp, and magnetic local time (MLT) as parameters, we conclude that the noon sector contains higher ULF Pc‐5 wave power compared with the other MLT sectors. The dawn, dusk, and midnight sectors have no statistically significant difference between them. The drift‐averaged power spectral densities are used to derive the magnetic and the electric component of the radial diffusion coefficient. Both components exhibit little to no energy dependence, resulting in simple analytic models for both components. More importantly, the electric component is larger than the magnetic component by one to two orders of magnitude for almost all L∗ and Kp; thus, the electric field perturbations are more effective in driving radial diffusion of charged particles in the inner magnetosphere. We also present a comparison of the Van Allen Probes radial diffusion coefficients, including the error estimates, with some of the previous published results. This allows us to gauge the large amount of uncertainty present in such estimates.

THE AGE DYNAMICS OF MULTIFACTOR EXPRESS INDICATORS of the functional STATE OF KAYAK AND CANOE ROWERS DURING TRAINING

Objective: to analyze the age dynamics of parameters of energy supply and functional state in kayak and canoe rowers during training. Material and methods: We examined 32 male sportsmen who were divided into 3 age groups (13-15, 16-18 and 19-21 years old). The functional state and the basic parameters of energy supply system of muscular activity of the sportsmen were evaluated by data of the computer program complexes «Omega-C» and «D-test» before and after training. Results: The data obtained make it possible to make a supposition that the age features of the parameters of aerobic capacity are closely interconnected with the resultant effect of vegetative regulation (TP waves), parasympathetic activity (HF waves) and especially sympathetic link, which is revealed in physical exercise (VLF, LF waves). Conclusion: the study revealed the degree of interconnection of functional and energetic parameters of the computer program complex «Omega-C» with the parameters of multifactor express-diagnostics by S. A. Dushanin with the use of the computer program complex «D-test». This method makes it possible to prognose organism reactions to physical exercise.

Global modeling of ULF waves at Mercury

AbstractULF waves in the ion cyclotron frequency range waves are regularly observed at Mercury's magnetosphere. Although previous statistical studies have shown that ULF waves are primarily compressional near the equator and transverse with linear polarization at higher latitude, the underlying reason for this distribution of wave polarization has not been understood. In order to address this key question, we have developed a two‐dimensional, finite element code that solves the full wave equations in global magnetospheric geometry. Using this code, we show that (1) efficient mode conversion from the fast compressional waves to the ion‐ion hybrid resonance occurs at Mercury consistent with previous calculations; (2) such mode‐converted waves globally oscillate similar to field line resonance at Earth; and (3) compressional wave energy is primarily localized near the equator, while field‐aligned transverse, linearly polarized waves generated by mode conversion at the ion‐ion hybrid resonance radiate to higher latitude. Based on these wave solutions, we suggest that the strong transverse component of observed ULF waves at Mercury in high magnetic latitude can be explained as excitation of the field line resonant waves at the ion‐ion hybrid resonance.

A ULF wave driver of ring current energization

AbstractULF wave radial diffusion plays an important role in the transport of energetic electrons in the outer radiation belt, yet similar ring current transport is seldom considered even though ions satisfy a nearly identical drift resonance condition albeit without the relativistic correction. By examining the correlation between ULF wave power and the response of the ring current, characterized by Dst, we demonstrate a definite correlation between ULF wave power and Dst. Significantly, the lagged correlation peaks such that ULF waves precede the response of the ring current and Dst. We suggest that this correlation is the result of enhanced radial transport and energization of ring current ions through drift resonance and ULF wave radial diffusion of ring current ions. An analysis and comparison of the ion and electron diffusion coefficients further support this conclusion, ULF waves providing an important missing physical transport process explaining Dst underestimation in ring current models.

Cardiac Autonomic Response to Saturated Fatty Meal in Overweight and Obese Young Females

The present study aimed to assess the effect of saturated fatty meal on heart rate variability (HRV) in overweight and obese young females.42 (18–23 years old) female volunteer students were included into the study. On 7th day of menstrual cycle, participants had high fat milkshakes at 8 a.m., 3 hours preceding HRV assessment.HRV indices included; standard deviation of all R‐R intervals (SDRR), root mean squares of successive differences between R‐R intervals (rMSSD), very low frequency waves (VLF), low frequency waves (LF), high frequency waves (HF). LF/HF ratio was calculated.The rMSSD and HF waves were significantly decreased in overweight and obese groups when compared to control group (P&lt; 0.01, P&lt; 0.001) and (P&lt;0.001, P&lt; 0.001) respectively.The LF waves showed significant increase in overweight group (P&lt;0.001) and significant decrease in obese group (P&lt;0.05).The LF/HF ratio was significantly increased in the overweight group (P&lt;0.001), and insignificantly different in the obese group. No significant correlations were found between body mass index, waist hip ratio and HRV parameters.The present study revealed loss of protective vagal influence on heart rate in overweight and obese young females.Interestingly, the present study showed a blunted sympathetic response to saturated fatty meal in obese young females, while in the overweight group, sympathetic hyperactivity was observed.

Reflection height of daytime tweek atmospherics during the solar eclipse of 22 July 2009

We report multipoint observations of daytime tweek atmospherics during the solar eclipse of 22 July 2009. Sixteen and sixty‐three tweek atmospherics were observed at Moshiri and Kagoshima, Japan, where the magnitudes of the solar eclipse were 0.458 and 0.966, respectively. This was the first observation of tweek atmospherics during a low‐magnitude eclipse (0.458). The average and standard deviation of the reflection height were 94.9 ± 13.7 km at Moshiri and 87.2 ± 12.9 km at Kagoshima. The reflection height at Moshiri was almost the same as that for normal nighttime conditions in July (96.7 ± 12.6 km) in spite of the low magnitude of the eclipse. The reflection height at Kagoshima seems be divided into two parts: propagation across the total solar eclipse path and propagation in the partial solar eclipse path. During the eclipse, we also observed the phase variation in the LF transmitter signals. The average change in the phase delay of the LF signals was 109° for the paths that crossed the eclipse path and 27° for the paths that did not cross the eclipse path. Assuming a normal daytime height for LF waves of 65 km, a ray tracing analysis indicates that the variations in phase correspond to a height increase of 5–6 km for the paths across the eclipse and 1–2 km for partial eclipse paths. The wide range of estimated tweek reflection heights at Kagoshima also suggests a difference in electron density in the lower ionosphere between total and partial solar eclipses.

Oscillatory structure of the parameters of the pulse signal of the radial artery

The typology analysis of the spectral density curves of time series obtained from various parameters of unit pulse oscillations was performed. The formal classification (typology) of spectral curves was performed using correlations of peak values of the spectral density of VLF, LF, and HF slow waves. To include a spectral density curve into a particular type, the criteria were introduced that characterize the intensity of these oscillatory components. The experimental data was collected during examinations of children and adolescents that were performed to detect the early stage of arterial hypertension (AH). The distribution of the subjects among the types of spectral density based on various parameters of pulse oscillation was evaluated. The results of the comparative analysis of spectral type distribution for various parameters are shown. This analysis has revealed the most informative spectral parameters for differential diagnosis of conditions of two types: type 1, essential hypertension, and type 2, various functional disorders with a normal blood pressure. It has been found that the parameters of the oscillatory components of dicrotic pulse wave time characteristics are the most informative for detecting hypertension in children.

Downward ELF/VLF Waves Radiation Excited by Ionospheric Artificial Modulation

AbstractBy heating the ionosphere with ELF/VLF‐modulated high‐power HF wave, a virtual antenna is produced in the ionosphere, which is an effective means to launch ELF/VLF waves. This paper uses the modulated‐heating models of Wang Feng [2009] to calculate the strength of the LF radiation source produced by HF heating, and analyzes attenuation and reflection of the LF wave transmitting downward using full‐wave algorithm. With HAARP experiment parameter, this work simulates magnetic field of the LF signals on the sea, which is of PT order of magnitude, consistent with the experimental data.

A New Approach to Parametric Modeling of Glottal Flow

Glottal waveform models have long been employed in improving the quality of speech synthesis. This paper presents a new approach for modeling the glottal flow. The model is based on three control volumes that strike a one-mass and two-springs system sequentially and generate a glottal pulse. The first, second and third control volumes represent the opening, closing and closed phases of the vocal folds, respec- tively. The masses of the three control volumes and the size of the first one are the four parameters that define the shape, pitch and amplitude of the glottal pulse. The model may be viewed as parametric approach governed by second order differential equations rather than analytical functions and is very flexible for designing a glottal pulse. The glottal pulse generated by the present model, when compared with those generated by Rosenberg, LF and mucosal wave propagation models demonstrates that it appropriately represents the opening, closing and closed phases of the vo- cal fold oscillation. This leads to the validity of our model. Numerical solution of the present model has been found to be very efficient as compared to its analytical solution and two other well-known parametric models Rosenberg++ and LF. The accuracy of the numerical solution has been illustrated with the help of analytical solution. It has been observed that the accuracy improves by increasing the size of the first control volume and may decrease insignificantly with increase in the mass of any of the control volumes. Two experiments with the present model support its successful implementation as a voice source in speech synthesis. Thus our model renders itself as an efficient, accurate and realistic choice as a voice source to be employed in real-time speech production.