Overtone Frequencies Research Articles

The Hasapi of the Batak Toba from Sumatra Indonesia

The hasapi of the Batak Toba from Sumatra, Indonesia is a plucked bowl-lute chordophone. Hasapi is a fretless chordophone with two strings. The tuning for the hasapi used in this study is based on the transcription of the song ‘Horbo Paung’ played in F major by Sam Sitio. The tuning used for the 2nd string is C4 (Do for open string) followed by D4, E4, and F4 for 1st, 2nd, and 3rd finger, respectively. The 1st string was tuned to G4 (So for open string), followed by A4, B4, and C5 for 1st, 2nd, and 3rd finger, respectively. At higher notes (1st string) the spectra did not display many harmonics, i.e., less partials compared to the lower note (2nd string). Both strings showed a regular signal, whereas the highest note C5 (the highest fundamental frequency from the 1st string) showed an irregular pattern with no significant overtone frequency. The intensity of the partials in both strings displayed the reduction in amplitudes i.e. not proportional to increasing harmonic frequency. The timbre from Adobe Audition showed that the time frequency analysis (TFA) was in accordance with the Picoscope spectra. Only TFA from C5 showed irregular pattern with respect to the Picoscope output.

Dual-mode AT-cut quartz resonant pressure sensor for wide pressure and temperature measurement ranges

In this paper, a dual-harmonic-mode excited resonant pressure sensor with an AT-cut all-quartz sensing element was developed to synergistically achieve a wide measurement range for both temperature and pressure, along with a fast transient response. In this device, the excited third overtone mode indicated the applied pressure, while the beat frequency generated by the overtone and fundamental modes was used for self-temperature compensation. At the same time, the sandwiched all-quartz sensitive structure design effectively addressed the limitations associated with narrow pressure and temperature ranges. Especially, the dual-mode self-temperature sensing mechanism has been validated in the subzero temperature range for the first time. Quartz crystal processing techniques were employed to manufacture the sensor, and key performance metrics were characterized. The experimental results demonstrated that the sensor achieved an accuracy of ± 0.015 % full scale (FS) under a pressure range of 0–120 MPa and a temperature range of −40 to 150 °C. The pressure sensitivity of the overtone frequency was quantified as 365 Hz/MPa, and the beat frequency provided a temperature accuracy of 0.4 °C. Additionally, the developed sensor exhibited fast transient response under dynamic pressure and temperature conditions attributed to its self-temperature compensation capability. Thus, this study provides a practical solution for high-pressure measurements across a wide temperature range, combined with excellent transient performance.

Quasinormal modes and their excitation beyond general relativity

The response of black holes to small perturbations is known to be partially described by a superposition of quasinormal modes. Despite their importance to enable strong-field tests of gravity, little to nothing is known about what overtones and quasinormal-mode amplitudes are like for black holes in extensions to general relativity. We take a first step in this direction and study what is arguably the simplest model that allows first-principle calculations to be made: a nonrotating black hole in an effective-field-theory extension of general relativity with cubic-in-curvature terms. Using a phase-amplitude scheme that uses analytical continuation and the Prüfer transformation, we numerically compute, for the first time, the quasinormal overtone frequencies (in this theory) and quasinormal-mode excitation factors (in any theory beyond general relativity). We find that the overtone quasinormal frequencies and their excitation factors are more sensitive than the fundamental mode to the length scale l introduced by the higher-derivative terms in the effective field theory. We argue that a description of all overtones cannot be made within the regime of validity of the effective field theory, and we conjecture that this is a general feature of any extension to general relativity that introduces a new length scale. We also find that a parametrization of the modifications to the general-relativistic quasinormal frequencies in terms of the ratio between l and the black hole’s mass is somewhat inadequate, and we propose a better alternative. As an application, we perform a preliminary study of the implications of the breakdown, in the effective field theory, of the equivalence between the quasinormal mode spectra associated to metric perturbations of polar and axial parity of the Schwarzschild black hole in general relativity. We also present a simple justification for the loss of isospectrality. Published by the American Physical Society 2024

Vis-NIR spectroscopic discriminant analysis of aflatoxin B1 excessive standard in peanut meal as feedstuff materials

A fast, simple and reagent-free detection method for aflatoxin B1 (AFB1) is of great significance to food safety and human health. Visible and near-infrared (Vis-NIR) spectroscopy was applied to the discriminant analysis of AFB1 excessive standard of peanut meal as feedstuff materials. Two types of excessive standard discriminant models based on spectral quantitative analysis with partial least squares (PLS) and direct pattern recognition with partial least squares-discrimination analysis (PLS-DA) were established, respectively. Multi-parameter optimization of Norris derivative filtering (NDF) was used for spectral preprocessing; the two-stage wavelength screening method based on equidistant combination-wavelength step-by-step phase-out (EC-WSP) was used for wavelength optimization. A rigorous sample experimental design of calibration-prediction-validation was utilized. The calibration and prediction samples were used for modeling and parameter optimization, and the selected model was validated using the independent validation samples. For quantitative analysis-based, the positive, negative and total recognition-accuracy rates in validation (RARV+, RARV-, and RARV) were 84.8 %, 74.6 % and 79.8 %, respectively; but, the relative root mean square error of prediction was as high as 51.0 %. For pattern recognition-based, the RARV+, RARV-, and RARV were 93.3 %, 90.5 % and 91.9 %, respectively. Moreover, the number of wavelengths N was drastically reduced to 17, and the discrete wavelength combination was in NIR overtone frequency region. The results indicated that, the EC-WSP-PLS-DA model achieved significantly better discrimination effect. Thus demonstrated that Vis-NIR spectroscopy has feasibility for the excessive standard discrimination of aflatoxin B1 in feedstuff materials.

Improved Calculation of the Shear Modulus of Rectangular Prisms from Their Resonant Frequency Overtones

Abstract The shear modulus (G) is an important parameter for characterizing the strength of and wave propagation through a given material. This study improves the empirical model for estimating shear modulus using the impulse excitation technique based on an experimental analysis of 19 soda-lime silica glass bars. Analysis of the frequency equations relating the shear modulus to the torsional resonant frequencies of rectangular prisms has been used to provide improved equations for calculating G for higher orders of vibration. These were tested by measuring the shear modulus of several novaculite rocks of different porosities up to the seventh order of vibration. These were found to be nearly frequency independent. The updated frequency equations provide a distinct improvement over previously available methods when values for higher order vibrations, and thus the frequency dependence of G, are of interest.

Vibrational Anharmonicity and Energy Relaxation in Nanoscale Acoustic Resonators.

The fundamental and n = 3 overtones of Au nanoplate thickness vibrations have been studied by transient absorption microscopy. The frequencies of the n = 3 overtone are less than 3× the frequency of the fundamental. This anharmonicity is explained through a continuum mechanics model that includes organic layers on top of the nanoplate and between the nanoplate and the glass substrate. In this model, anharmonicity arises from coupling between the vibrations of the nanoplate and the organic layers, which creates avoided crossings that reduce the overtone frequencies compared to the fundamental. Comparison of the experimental and calculated quality factors shows that coupling occurs to the top organic layer. Good agreement between the measured and calculated quality factors is obtained by introducing internal damping for the nanoplate. These results show that engineering layers of soft material around metal nanostructures can be used to control the vibrational lifetimes.

Mechanical overtone frequency combs

Mechanical frequency combs are poised to bring the applications and utility of optical frequency combs into the mechanical domain. So far, their main challenge has been strict requirements on drive frequencies and power, which complicate operation. We demonstrate a straightforward mechanism to create a frequency comb consisting of mechanical overtones (integer multiples) of a single eigenfrequency, by monolithically integrating a suspended dielectric membrane with a counter-propagating optical trap. The periodic optical field modulates the dielectrophoretic force on the membrane at the overtones of a membrane’s motion. These overtones share a fixed frequency and phase relation, and constitute a mechanical frequency comb. The periodic optical field also creates an optothermal parametric drive that requires no additional power or external frequency reference. This combination of effects results in an easy-to-use mechanical frequency comb platform that requires no precise alignment, no additional feedback or control electronics, and only uses a single, mW continuous wave laser beam. This highlights the overtone frequency comb as the straightforward future for applications in sensing, metrology and quantum acoustics.

Temporal variation in the depth of the magma surface at Aso volcano in 2014–2015

Monitoring the depth of the magma surface at open-vent volcanoes can be a practical tool to infer temporal variations in the magma supply during an eruption. We focus on the magmatic eruption of Aso volcano in 2014–2015 to estimate the temporal change in the depth of the magma surface, and show that this needs to be coupled with an understanding of the shallow conduit geometry if it is to be done in a representative manner. The eruption lasted 5 months from November 2014 and ending with a crater floor collapse in May 2015. During the eruption, we recorded seismo-acoustic waveforms related to frequent Strombolian explosions. The infrasound signals show several distinct peak frequencies derived from acoustic resonance inside the vent. We estimate the depth of the magma surface using the time delay of seismo-acoustic signals and the peak frequency of infrasound signals. In addition, the temporal variation in the shape of the conduit is constrained by the overtone frequency of the acoustic resonance. From the beginning of the eruption to early-January 2015, the magma surface was located at a depth of sim 200 m, and the conduit was a cylindrical pipe. Later, between January and February, the magma surface rose to sim 120 m, and the shape of the conduit changed to a conical frustum flaring inside. This finding indicates that the magma was injected into the shallow conduit and that it heated and weakened the conduit wall near the magma surface. Before the cessation of the magmatic eruption, the magma surface dropped by approximately 70 m. This magma drainage and, primarily, the instability of the conduit shape caused the crater floor to collapse. We show the possibility of tracking and assessing the depth of the magma surface and the shallow conduit geometry even with limited seismo-acoustic observations.

The Photometric Analysis and Classification of High Amplitude δ Scuti: AE Ursae Majoris

AE UMa, a Population I high amplitude Delta Scuti (HADS), was observed for 4 nights through 14-21 March 2022. 454 Visual CMOS observations and 11 new times of maxima were obtained over a period of ~19.4 hours in total. Using python coding and Fourier analysis, a fundamental frequency ƒ0 = 11.6251 cd-1 was established and further observation of amplitudes of light maxima led to beat phenomenon period Pb = 0.29360 d. Subsequently, the first overtone frequency ƒ1 = 15.0316 cd-1 was calculated and the period ratio = 0.7734 was found to be relatively unchanged from Szeidl (1974). Thereafter, the period ratio-metallicity correlation determined by Hintz et al. (1997b) was used to estimate the metallicity [Fe/H] of AE UMa. I concluded that AE UMa is incorrectly classified as a Pop. II HADS (SX Phoenicis) and should be grouped with Pop. I HADS.

Differential Tunneling-Driven and Vibrationally-Induced Reactivity in Isomeric Benzazirines.

Quantum mechanical tunneling of heavy-atoms and vibrational excitation chemistry are unconventional and scarcely explored types of reactivity. Once fully understood, they might bring new avenues to conduct chemical transformations, providing access to a new world of molecules or ways of exquisite reaction control. In this context, we present here the discovery of two isomeric benzazirines exhibiting differential tunneling-driven and vibrationally-induced reactivity, which constitute exceptional results for probing into the nature of these phenomena. The isomeric 6-fluoro- and 2-fluoro-4-hydroxy-2H-benzazirines (3-a and 3'-s) were generated in cryogenic krypton matrices by visible-light irradiation of the corresponding triplet nitrene 3 2-a, which was produced by UV-light irradiation of its azide precursor. The 3'-s was found to be stable under matrix dark conditions, whereas 3-a spontaneously rearranges (τ1/2 ∼64 h at 10 and 20 K) by heavy-atom tunneling to 3 2-a. Near-IR-light irradiation at the first OH stretching overtone frequencies (remote vibrational antenna) of the benzazirines induces the 3'-s ring-expansion reaction to a seven-member cyclic ketenimine, but the 3-a undergoes 2H-azirine ring-opening reaction to triplet nitrene 3 2-a. Computations demonstrate that 3-a and 3'-s have distinct reaction energy profiles, which explain the different experimental results. The spectroscopic direct measurement of the tunneling of 3-a to 3 2-a constitutes a unique example of an observation of a species reacting only by nitrogen tunneling. Moreover, the vibrationally-induced sole activation of the most favorable bond-breaking/bond-forming pathway available for 3-a and 3'-s provides pioneer results regarding the selective nature of such processes.

Raman Scattering in a Double-Doped Single Crystal LiTaO3:Cr(0.2):Nd(0.45 wt%)

The Raman spectra of a lithium tantalate crystal doubly doped with chromium and neodymium LiTaO3:Cr(0.2):Nd(0.45 wt%) have been studied in this paper. Raman spectra of the first and second orders have been found to be located against the background of a luminescent halo with a maximum at ≈1250 cm−1. Several Raman bands have been detected in the frequency range of 900–2000 cm−1. Their frequencies were 940, 1034, 1113, 1171, 1250, 1343, 1428, 1491, 1582, 1735, 1838, and 1925 cm−1. These bands correspond to overtone processes. We have determined that the frequencies of 1838 and 1925 cm−1 bands are significantly higher than the exact value of the overtone frequency corresponding to the fundamental mode 4A1(z)LO (864 cm−1).

Effect of Transitional Layer on Frequency of Kink Oscillations

In this article we study the effect of a transitional layer in a magnetic tube on the real part of the frequencies of kink oscillations. In our analysis, we use the model of a straight magnetic tube with the density and cross-section radius varying along the loop, and the thin-tube thin-boundary (TTTB) approximation. First, we calculate the correction to the fundamental frequency and show that it is positive and of the order of the ratio of the transitional layer thickness to the loop radius ell . The increase in the fundamental frequency results in the decrease in the estimate of the magnetic-field magnitude. Then we study the effect of the transitional layer on the ratio between the fundamental frequency and the first overtone frequency that is used for estimating the atmospheric scale height. We show that the correction to the frequency ratio is of the order of ell ^{2}, and thus it can be neglected for moderate values of ell .

Gravitational Wave Signatures of Black Hole Quasinormal Mode Instability.

Black hole (BH) spectroscopy has emerged as a powerful approach to extracting spacetime information from gravitational wave (GW) observed signals. Yet, quasinormal mode (QNM) spectral instability under small scale perturbations has been recently shown to be a common classical general relativistic phenomenon [J. L. Jaramillo et al., Phys. Rev. X 11, 031003 (2021)PRXHAE2160-330810.1103/PhysRevX.11.031003]. This requires assessing its impact on the BH QNM spectrum, in particular on BH QNM overtone frequencies. We conclude (i)perturbed BH QNM overtones are indeed potentially observable in the GW waveform, providing information on small-scale environment BH physics, and (ii)their detection poses a challenging data analysis problem of singular interest for LISA astrophysics. We adopt a twofold approach, combining theoretical results from scattering theory with a fine-tuned data analysis on a highly accurate numerical GW ringdown signal. The former introduces a set of effective parameters (partially relying on a BH Weyl law) to characterize QNM instability physics. The latter provides a proof of principle demonstrating that the QNM spectral instability is indeed accessible in the time-domain GW waveform, though certainly requiring large signal-to-noise ratios. Particular attention is devoted to discussing the patterns of isospectrality loss under QNM instability, since the disentanglement between axial and polar GW parities may already occur within the near-future detection range.

Modeling method and miniaturized wavelength strategy for near-infrared spectroscopic discriminant analysis of soy sauce brand identification

The identification of soy sauce brands can avoid adulteration and fraud, which is meaningful for food safety screening. Using visible and near-infrared (Vis-NIR) spectroscopy combined with k-nearest neighbor (kNN), the four-category discriminant models of soy sauce brands were established. The soy sauce of three brands (identification) and the other ten brands (interference) were collected, and a total of four categories of samples were obtained. The spectral datasets of two measurement modals (1 mm, 10 mm) were obtained. Based on moving-window (MW) waveband screening and wavelength step-by-step phase-out (WSP), the MW-WSP-kNN algorithm was proposed and applied to the wavelength optimization for the four-category discriminant analysis. Using calibration-prediction-validation experiment design, various high accuracy models with a small number of wavelengths located in NIR region were determined. In the independent validation, for the 1 mm measurement modal, the selected thirty-five dual-wavelength models and one three-wavelength model were located in NIR combined and overtone frequency regions respectively, all achieved 100% total recognition accuracy rate (RARTotal); for the 10 mm measurement modal, the selected seven three-wavelength models located in NIR overtone frequency region all reached more than 96.8% RARTotal, and the optimal RARTotal was 97.8%. The results showed the feasibility of small number of wavelengths' NIR spectroscopy applied to multi-category discriminant of soy sauce brands, with the advantages of rapid, simple and miniaturized. The proposed various small number of wavelengths' models provided a valuable reference for the design of small dedicated spectrometer with different measurement modals. The integrated optimization method and wavelength selection strategy here are also expected to be applied to other fields.

Second-Order Raman Scattering in Ferroelectric Ceramic Solid Solutions LiNbxTa1−xO3

In the second-order Raman spectra of ceramic solid solutions, LiNbxTa1−xO3 weak overtone bands of fully symmetric fundamental polar excitations were observed for the first time. The frequencies of the two bands exceeded the value of the overtone frequency corresponding to the fully symmetrical vibration 4A1(z). The possibility of the existence of phonon bound states of the antipolar type in the vibrational spectrum of LiNbxTa1−xO3 ceramics is predicted.

МЕТОД СВЧ АКУСТИЧЕСКОГО ИССЛЕДОВАНИЯ МАТЕРИАЛОВ ПОД ВЫСОКИМ ДАВЛЕНИЕМ

The arrangement of a new integrated measuring system (IMS) "HBAR + DAC" and its application to study changes in the acoustic properties of a paper and polycrystalline molybdenum samples under the influence of high pressure are discussed. When creating an IMS for the synthesis of piezoelectric films of aluminum-scandium nitride, the magnetron deposition method was used. The quality and thickness of the films were controlled by X-ray diffraction analysis and atomic force microscopy. For the first time, it is shown that the HBAR in the IMS content has good operational characteristics in the microwave band up to 8.8 GHz under the high-pressure impact on the samples. A decrease in the Q-factor of an HBAR as a sensitive element occurred to values of ~2500 – 3000 at the upper pressure limit, which is quite sufficient for accurate measurements of the resonant frequencies of acoustic overtones. The possibilities of IMS for studying the features in the behavior of solids under the high-pressure impact and the registration of plastic deformations in metals are demonstrated. It is found that the pressure dependence of the relative frequency shift of overtones during compression of a paper sample has a linear character. Thanks to this, the calibration of the high-pressure chamber on diamond anvils was performed using the RAMAN method. It is found that the frequency shift of overtones allows more accurately determining the stresses in the diamond anvil up to 5 GPa. When compressing a sample of polycrystalline molybdenum, the phenomena of plastic deformation and creep, as well as the transit flight of an acoustic wave through the sample, starting from a pressure of 3 GPa, were detected. The results obtained will be useful for researchers, students and postgraduates in the fields of high pressure physics and physical acoustics.

The Frequency Spectrum and Time Frequency Analysis of Different Violins Classification as Tools for Selecting a Good-Sounding Violin

This work evaluates four violins from three distinct manufacturers, notably Eurostring, Stentor, and Suzuki, using a scientific approach. Eurostring1 and Eurostring2 were the names given to the two Eurostring units. The purpose of this study is to identify elements in various violins that could be used as tools for selecting a pleasantsounding violin by having them classified by a professional violinist. The signal’s time varying frequency was evaluated using a frequency spectrum and a time frequency plane, and the combination of frequency spectrum and time frequency domain is utilised. PicoScope oscilloscopes and Adobe Audition version 3 were used to record the acoustic spectra in terms of time and frequency. The time frequency plane is identified, and time frequency analysis (TFA) is produced by Adobe Audition spectrograms. The sound was processed in order to generate Fast Fourier Transform analysis: Fourier spectra (using PicoScope) and spectrograms (using Adobe Audition). Fourier spectra identify the intensity of the fundamental frequency and the harmonic spectra of the overtone frequencies. The highest frequencies that can be read are up to and including the 9th overtone. All violins have a constant harmonic overtone pattern with an uneven acoustic spectrum pattern. Eurostring1 showed inconsistent signal in the string G with 6th and 7th overtone missing, whereas Eurostring2 lack of the 6th overtone. Among the string D, only Eurostring1 display an exponential decay for the overtone. All the string A except for Suzuki showed nice and significant peak of fundamental and overtone. Stentor displays up to the 5th overtone. Among the string E, Suzuki showed inconsistent harmonic peak intensity. TFA revealed that the fundamental frequency of string E for Eurostring1 was lower than the first overtone. Only Eurostring1 has an uneven decay for the overtone frequency, whereas Eurostring2 exhibits a large exponential decay for the overtone frequency.

Voice source, formant frequencies and vocal tract shape in overtone singing. A case study

Purpose: In overtone singing a singer produces two pitches simultaneously, a low-pitched, continuous drone plus a melody played on the higher, flutelike and strongly enhanced overtones of the drone. The purpose of this study was to analyse underlying acoustical, phonatory and articulatory phenomena. Methods: The voice source was analyzed by inverse filtering the sound, the articulation from a dynamic MRI video of the vocal tract profile, and the lip opening from a frontal-view video recording. Vocal tract cross-distances were measured in the MR recording and converted to area functions, the formant frequencies of which computed. Results: Inverse filtering revealed that the overtone enhancement resulted from a close clustering of formants 2 and 3. The MRI material showed that for low enhanced overtone frequencies (F E) the tongue tip was raised and strongly retracted, while for high F E the tongue tip was less retracted but forming a longer constriction. Thus, the tongue configuration changed from an apical/anterior to a dorsal/posterior articulation. The formant frequencies derived from the area functions matched almost perfectly those used for the inverse filtering. Further, analyses of the area functions revealed that the second formant frequency was strongly dependent on the back cavity, and the third on the front cavity, which acted like a Helmholtz resonator, tuned by the tongue tip position and lip opening. Conclusions: This type of overtone singing can be fully explained by the well-established source-filter theory of voice production, as recently found by Bergevin et al. [1] for another type of overtone singing.

The effect of bamboo clip dimension and position towards the frequency spectrum of a vibrating inhomogeneous bundengan string

Bundengan is a traditional musical instrument from Indonesia. One of its unique features is the ability to produce sound imitating the gamelan, a percussive metallophone. This is generated by plucking on the bundengan strings, which have small bamboo clips attached to them. In this work, the effect of the clip dimension and position on the frequency spectrum of the vibrating string is analysed by means of computer simulation and experiment. The string was modelled using Scilab, taking into account the transversal and rotational vibration of the string and bamboo clip, including air drag force. The height to diameter ratio of the clip can be varied in the model. Furthermore, we set up a bundengan string on a sonometer with no resonator, attached specially made bamboo clips on it, and measured the sound frequency spectrum of the vibrating string. The results showed that increasing the height to diameter ratio of the clip decreased the overtone frequencies of the string. It was also found that the fundamental frequency of the string decreased, but its overtones increased, when the clip is shifted towards the middle of the string. The frequency spectrum from the simulation corresponds well to that from the experiment.

Polar modes and overtone states in Raman spectra of lithium tantalate crystals

The conditions for the excitation of transverse and longitudinal polar modes in the processes of Raman scattering of light in mono- and polydomain lithium tantalate single crystals are established using a backscattering geometry. The relative intensity of the overtone Raman spectrum on the longitudinal and transverse fundamental polar excitations is much higher in the polydomain sample. Unfortunately, the exact reason for the difference in the Raman spectra of the mono- and polydomain lithium tantalate samples is unknown. The frequencies of the two overtone bands exceeded the exact value of the overtone frequency corresponding to the fundamental longitudinal polar mode $4{A}_{1}(\text{LO})$, which clearly indicates the existence of bound phonon pairs (biphonons). This is consistent with theory and has been shown for both mono- and polydomain samples. On the basis of the general theory of bound states of quasiparticles, the possibility of the existence of bound states of quadrupole excitations of the antipolar type in the vibrational spectrum of a polydomain crystal of lithium tantalate is predicted.