Sound Frequency Range Research Articles

Monitoring and Studying Audible Sounds Inside Different Types of Soil and Great Expectations for its Future Applications

A majority of seismological studies are concerned with soil properties in low frequencies (1–10 Hz), but little is known about these properties in the audible sound domain (20–20,000 Hz). This is probably due to the high attenuation of the high frequencies within the soil, resulting in a minimal effect on buildings. For this study, 172 stations were recorded over different types of soils using variable types of P-wave and S-wave geophones to examine the variation of soil properties in the range of audible sound (20–3000 Hz). High resolution 32 bit spectrograms for the sounds recorded within every soil sample were analyzed. Moreover, a model for empty room was built in the subsurface to study changes in sound caused by the existence of large voids or cavities in the subsurface. The sound wave was able to differentiate between rigid, hard soil and softer, weaker soil. While high-strength rocks or soils tend to show sharp sound pitches (300–3000 Hz), weaker soils show lower sound pitches (20–100 Hz). The existence of subsurface voids or cavities tend to make sound pitches more regular, higher and sharper than those in the surrounding soils. This is most probably due to resonance of sound in closed places (e.g. a violin). Soil energy levels and how they change due to the soil’s excitation were studied. Soil research in the field of audible sounds is considered an emerging field with several applications (e.g. geological hazards, water exploration, and oil exploration and so on). There is a need for special high-resolution equipment to be developed for the same. This equipment should be capable of recording wide range of sound frequencies preserved in the soil and directly producing high-resolution spectrograms.

Dielectric properties of silicosillenite crystals doped with chromium and manganese ions

The effect of chromium and manganese ions on the dielectric properties of Bi12SiO20 crystals is studied by the dielectric spectroscopy methods in the sound frequency range in the temperature range 280 – 800 K.

Effect of different factors on sound absorption property of porous concrete

As a functional pavement material with a large number of pores, porous concrete (PC) pavement exhibits a good sound absorption performance. Limited experimental studies focused on the effects of aggregate size, cement to aggregate ratio, and pavement thickness of porous concrete on its sound absorption in a wide range of sound frequencies. Besides, the effects of temperature and humidity on the sound absorption performance of porous concrete are still unclear. In this study, one hundred and thirty-five samples of porous concrete were prepared that consist of three aggregate gradations, three cement to aggregate (C/A) ratios and three thicknesses to investigate the sound absorption property of porous concrete considering the effects of temperature and humidity. These samples were tested at different temperatures (−10, 5, 20, 35 and 50 °C) and with different humidity (dry, inundated and saturated) using impedance tubes method with varied sound frequencies (200–2000 Hz). The results demonstrated that: under the same conditions, the sound absorption property of porous concrete decreases with the increase of aggregate size and cement to aggregate ratio, and increases with the increase of thickness. In addition, the temperature and presence of water have significant effects on the sound absorption property of porous concrete.

Does a pitch rating method converge on the frequencies within tonal stimuli?

This study determined how well the "perceived spectrum," estimated using a pitch similarity rating method, reflected the spectrum and pitch of seven different tonal sounds. The perceived spectrum well-matched the acoustic spectrum for pure tones ranging from 1 to 12 kHz, it also matched the broad frequency range for two complex tones with periodicity pitches of 1 and 2 kHz, but it did not reflect the pitch of the complex tones. These results suggest that while this method may not measure the pitch of sounds, it may be useful for measuring the general perceived frequency range of sounds.

Visualization Of Cell Signal Transduction By The Method Of Microwave Dielectrometry At Dilated Cardiomyopathy

The results of processing the transduction of the cell signal in erythrocytes under physiological conditions and duringdevelopment of dilated cardiomyopathy are presented. The microwave dielectrometry method was tested to visualize the electromagnetic signal from a suspension of erythrocytes using the “sweep”-regime of a piezoelectric cell in the sound frequency range f=10÷12000 Hz. Erythrocyte hydration was estimated by the parameter of the real part of the complex permittivity e′ at a frequency of 37.7 GHz. The use of a stimulator and modulator of β-adrenergic receptors – adrenaline and prostaglandin E2 allowed us to simulate a violation in the system of transduction of the cell signal through the adenylate cyclase system of erythrocytes in vitro. Analysis of the erythrocyte’s electromagnetic response spectra in the “sweep”-regime recorded differences in the intact and experimental samples, as well as during the screening of the additives used. The dielectric data were verified with the data of echocardiography and radiography, which made it possible to recommend microwave dielectrometry as one of the methods of non-invasive operative diagnosis of dilated cardiomyopathy

Effects of acoustic fields on the dynamics of micron-sized particles in a fluidized bed

The effect of external acoustic fields on hydrodynamic behavior of cohesive micron-sized particles in a pseudo-2D fluidized bed is studied using CFD-DEM simulations. The forces acting on a particle consist of the contact force and cohesive force between particles, the drag force by the surrounding fluid and the sound force by an acoustic field. A wide range of sound pressure levels and sound frequencies are investigated in terms of their effects on the pressure drop, bed expansion, distribution of particle velocity and concentration, as well as the sizes of bubbles and agglomerates. Comparing to the system without acoustic force, the application of acoustic field is found to induce the breakup of the formed agglomerates, and ultimately lead to a stable bubbling fluidization regime. A useful range of frequencies between 80 Hz to 100 Hz is found with a pressure level of 120 dB, resulting in most remarkable improvement of the process performance.

Numerical simulation of acoustic agglomeration of fine particles in sintered flue gas of steel production

Fine particles in the sintering flue gas of steel production account for the vast majority, which is the primary control object of PM2.5 emission sources. Traditional dust removal methods have low capture efficiency for fine particles below 1 micron. Previous research on acoustic agglomeration has focused on broad-spectrum smoke, and there is a lack of understanding of the agglomeration process of sub-micron narrow-spectrum case. Based on the zoning method, the time evolution data of particle size distribution (PSD) and agglomeration efficiency corresponding to different frequencies, sound pressure levels (SPLs), and particle concentrations under the sub-micron narrow-spectrum condition are calculated in this paper. The data analysis shows that the agglomeration efficiency of the fine particle dominated flue gas increases with the increase in the frequency of action. High sound intensity conditions are conducive to improving the agglomeration efficiency, and high flue gas concentration conditions can significantly reduce the emission reduction time and energy consumption. Compared with broad-spectrum flue gas, due to the small difference in particle size and movement speed, under the same action conditions, fine particles occupy a longer agglomeration time, and the required acoustic intensity is higher, which is not conducive to practical industrial applications. Therefore, after adding a small amount of large-size particles, the acoustic agglomeration of fine particles dominated smoke was studied. Theoretical analysis shows that the presence of a small number of large particles in the flue gas significantly enhances the agglomeration efficiency and reduces the time of action and the acoustic intensity. In-plant tests verified the feasibility of acoustic agglomeration in the real-time treatment of sintered flue gas and the advantage of adding a small amount of large particles. The test sound frequency range is 50 Hz to 2 kHz, the fundamental frequency SPL is 87.3 ~ 161.8dB, and the action time is within 3s. The measured PM2.5 emission reduction efficiency is 16% ~ 92%, and the optimal frequency is about 800Hz.

Behavioral assessment of in-air hearing range for the Pacific walrus (Odobenus rosmarus divergens)

The conservation status of wild walruses (Odobenus rosmarus) is influenced by rapid warming of the Arctic, loss of seasonal sea ice, and increasing pressures related to anthropogenic activities and associated noise. Few data are available regarding acoustic sensitivity in walruses, although the species is known to be vulnerable to human disturbance. Here, we provide new information to describe the range of sound frequencies that are audible to walruses. These data were obtained through partnership with the Walrus Conservation Consortium and two zoological facilities. Two adult female walruses were trained to cooperate in an auditory detection task by responding to relatively high-amplitude airborne tones of approximately 80 dB re 20 μPa. Once performance was reliable, behavioral responses were generalized to a range of frequencies spanning more than six octaves. The upper- and lower-frequency limits of hearing were determined during audiometric testing with fully calibrated sounds. Results confirmed an audible range of hearing extending from 60 Hz to 23 kHz in air. Hearing range in water is expected to be similar or broader at high frequencies. This study provides evidence that hearing in walruses is different from that of other marine carnivores, including seals, sea lions, and sea otters, and better than suggested by early reports for the species.

МЕТОД АМПЛИТУДНОЙ МОДУЛЯЦИИ ВЫСОКОЧАСТОТНОГО КОРОННОГО РАЗРЯДА

Коронний розряд знайшов своє застосування в різних галузях науки і техніки. Коронний розряд, що протікає при високих частотах, застосовується для поверхневого легування металів і напівпровідників, для очищення газів від пилу в складі електростатичних фільтрів, для діагностики станів конструкцій. У статті наводяться результати дослідження з управління розрядом за допомогою амплітудної модуляції.

Improving the removal of inhalable particles by combining flue gas condensation and acoustic agglomeration

In order to develop the high efficiency and cost-effective particle removal technology, a novel particle removal unit combined flue gas condensation and acoustic agglomeration was designed based on theoretical analysis. The performance of the designed combined particle removal unit was evaluated by the laboratory scale experiments. Compared with the single external field of sound or condensation, the combination of the two external fields made the removal efficiency higher. The maximum total removal efficiency could be up to 70% when the sound frequency was 1500 Hz, the sound pressure level (SPL) was 141 dB, and the cooling water flow rate was 560 L/h. With the increase of flue gas temperature drop, the removal efficiency increased. In addition, more waste water and heat could be recovered from the flue gas. There was an optimal sound frequency range of 1500–2000 Hz for the combined particle removal unit, and the removal efficiency decreased whether the sound frequency increased or decreased. The removal efficiency increased with the rise of SPL, but the considerable improvement was obtained only when the SPL exceeded 120 dB. Therefore, there was an SPL threshold for the application of combined particle removal unit. Through the techno-economic comparisons with other technologies, the novel particle removal unit was proved to be a highly efficient and cost-effective particle removal technology.

Nonlinear optical re-orientation and photoacoustic properties of indium tin oxide nanoparticles

Abstract The nonlinear optical Kerr effect of indium tin oxide (ITO) nanoparticles (NPs) was investigated using continuous wave laser beams. ITO NPs were synthesized using the sol-gel method and were prepared as a colloid and a thin film. The structural and optical properties of the synthesized particles were characterized by X-ray diffraction analysis, transmission electron microscopy and UV–visible spectroscopy. The energy band gap was found to be 3.45 eV. The nonlinear optical properties of these NPs were measured by two sources: one He–Ne laser beam and a diode laser beam at wavelengths of 632.8 nm and 450 nm, respectively. For the He–Ne laser beam, the obtained nonlinear refractive index was found to be n 2 = + 1.7 × 10 − 7 c m 2 W , which its plus sign indicates that the main nonlinear refractive phenomenon involved was the optical re-orientation effect due to the electric dipole moment of the particles. The high nonlinear absorption of the particles at both wavelengths leads to the creation of intensity-dependent photoacoustic (PA) signals that are mainly in the audible range of sound frequencies. The sonic waves were within a frequency interval of 2–19 KHz. The ITO particles were present as NPs, which simultaneously show optical re-orientation and PA responses under continue wave (CW) laser irradiations. This research thus finds that ITO NPs are a good candidate for electro-optical sensors and applications.

Evolution of Low-Frequency Band Gaps Using X-Shapes and Single-Sided Stubbed Phononic Crystals

In this work, the evolution of dispersion relations of 2D asymmetric phononic crystals in the low-frequency range is introduced and discussed. Two phononic crystal structures are proposed and calculated using Finite Element method. The first one is a thin plate from PDMS with a circular one-side stubbed from tungsten and the other is a thin plate in the X-shape from rubber and tungsten. The effects of some parameters such as stub height and diameter on the phononic band gap value are studied. Low-frequency band gaps can be found in both structures with frequencies corresponding to the audible sound frequency range. The symmetry and shape of the stub has a remarkable influence on the band structures. Where, the proposed one-side stubbed exhibits a phononic band gap in a lower frequency range compared with the published studies about the double side stubbed. Furthermore, with the same thickness value the band gap value was reduced in the X-shape phononic stub compared with the one-side stubbed. These results may be useful for the low-frequency and noise suppression devices.

Dynamic Stabilization of Foam Films with Acoustic Sound.

This paper demonstrates the stabilization of single foam films at dynamic conditions induced by exposure to the acoustic sound. The foam films were formed from aqueous solutions using a Sheludko cell. In the presence of sound at certain sound frequencies and above certain thresholds of sound amplitude, the lifetime of the film with 1 × 10-4 M sodium dodecyl sulfate (SDS) in the presence of 0.1 M NaCl was significantly increased, and a stabilization map was drawn to show the three levels of film stability (i.e., unstable, metastable, and stable) obtained over a broad range of sound frequencies (1-19 kHz) and amplitudes (74-125 dB). In particular, stable films were observed at relatively high frequencies (14-19 kHz) and high amplitudes (>107 dB) and metastable films were observed at intermediate frequencies (8.8-9.3 kHz) and high amplitudes (>111 dB). The stabilization effect was also demonstrated with different surfactants at different concentrations, at different electrolyte concentrations (in the presence and absence of the surfactant), and at different temperatures. Image analysis suggested the presence of liquid flow within the films that were stabilized by exposure to the acoustic sound. The stabilization effect could be attributed to the hydrodynamic pressure arising at dynamic conditions.

Effect of Coating Thickness on Sound Absorption Property of Four Wood Species Commonly Used for Piano Soundboards

Effects of polyurethane (PU) coating thicknesses (0.15, 0.30, 0.45, and 0.60 mm) on sound absorption coefficients of four wood species were investigated using the standing wave ratio method with an input sound vibration frequency range set between 125 and 4000 Hz. Wood species of four specific gravity (SG) levels were Korean spruce, European spruce, Sitka spruce, and Picea brachytyla. Experimental results indicated that PU coating can significantly increase sound absorption coefficients of higher SG species such as Sitka spruce and Picea brachytyla in all tested frequency levels, but this significant increase was not observed in lower SG species such as Korean and European spruces when tested in the frequency range from 800 to 2000 Hz. Effects of coating thickness on sound absorption coefficients of four evaluated species were found to interact with wood SG values and input sound vibration frequency ranges. Specifically, coating 0.30-mm-thick PU on Korean and European spruces tends to result in significantly lower sound absorption coefficients among the ones coated with four evaluated thicknesses when tested at the frequency less than 800 Hz, but PU coating thickness resulting in lower sound absorption coefficients on Sitka spruce and Picea brachytyla was 0.15 mm. Sitka spruce and Picea brachytyla coated with 0.30- and 0.6-mm-thick PU had lower sound absorption coefficients when tested at the frequency ranging from 1000 to 2000 Hz. When tested at the frequency greater than 2500 Hz, sound absorption coefficients of four coated species increased as coating thickness increased from 0.30 to 0.60 mm with an increment of 0.15 mm, but these four species coated with three thicker PU had significantly lower sound absorption coefficients than the ones coated with 0.15-mm-thick PU. The uncoated higher SG species tended to have lower sound absorption coefficients than uncoated lower SG ones when tested in the frequency ranging from 500 to 4000 Hz, but the differences were not found when tested under the frequency less than 400 Hz. Coating four species with different thicknesses of PU could alter their SG effects on their sound absorption coefficients.

The cancellation of human sounds using synthesized soundwaves

The principle of destructive interference is applied to reduce or eliminate the spoken sound in order to increase speech privacy. This research is divided into two parts: the synthesis of sound from formula, using both analytical linguistics and physical approaches, and the actual cancellation of simple to complex sounds in the real world setting. The results suggested that in a real-world setting, up to 60% intensity reduction could be repeatedly detected. When the complexity of the sound is increased, difference in interference pattern could be detected between sounds in frequency range within the human hearing spectrum. Furthermore, it is found that the generation of negative sound using the four formants is not comprehensive enough to interfere effectively with actual sound, therefore the spectral slice is needed to synthesize more complex sounds. After testing various variations, it is found that using 11 most intense frequency components adjusted in proportion according to each original amplitude best cancel the widest range of human sound samples. This method was used to test the effectiveness of actual human sound cancellation. Though effective cancellation was detected in the high frequencies range of the sound spectrum, other frequency ranges were barely affected. The difference between cancellation patterns of each frequency range might need investigating before the cancellation of human sound can be effectively applied in real life.

Creation of zinc oxide based nanomaterials by repetitively pulsed laser treatment

By repetitively pulsed laser treatment with a frequency of 500 Hz was metal/semiconductor nanocomposite on a basis of zinc oxide nanowires created. An analysis of results made it possible to find that with described laser-induced vibroexcitation of samples, vibration speed increases for frequencies multiple to frequency of the initial oscillation, and when frequency is increasing the amplitude is decreasing. Samples heating particularities in consequence of laser irradiation were determined. Analysis of X-ray diffraction images showed that the zinc oxide creation on the porous copper-zinc alloy substrate occurs as a result thermal oxidation by the repetitively pulsed laser treatment. It is shown that intensification condition of mass transfer in a solid state of a metal material is a local non-stationary deformation that is produced by a highly-powered outer action. Using of synergies of thermal action and vibrations in a sound frequency range caused by laser irradiation, provides opportunity of a new approach realization for the structures creation of composite nanomaterials on a basis of zinc oxide in metal/semiconductor Cu/ZnO nanocomposite.

Exploring the soundscape of small freshwater lakes

Monitoring freshwater ecosystems using passive acoustics is a largely unexplored approach, despite having the potential to yield information about the biological, geological and anthropogenic activity of a lake or river system. The state of Minnesota, located in the upper Midwest of the USA and nicknamed ‘land of 10,000 lakes’, provides an interesting case study for soundscape research, because lakes offer ecological, recreational and economic value throughout the area. The underwater soundscape was monitored at fifteen small lakes <10 km2 on representative days in winter (during 100% ice cover) and summer 2018 using a hydrophone suspended 2 m below the water's surface. Median broadband sound pressure level (100–12,000 Hz) was significantly lower in winter (57.2 dB re 1μPa) compared to summer (66.7 dB re 1μPa), possibly because low frequency wind sounds were reduced in winter. Recordings suggest small freshwater lakes in Minnesota have a relatively pristine soundscape, where vocalizing aquatic animals may hold acoustic niches. However, sound from anthropogenic activity was also present in the study lakes. Ice auger and motorboat sound increased the intensity of the soundscape by 10 dB and overlapped the frequency range (300–1000 Hz) of biological sounds in the environment, that may be important to aquatic life. Understanding current baseline sound levels in ecologically significant freshwater lakes, like those in this study, is the first step in determining any potential consequences of anthropogenic sound. Moving forward, baseline sound levels provide vital evidence for scientists and governing bodies to make proactive decisions for soundscape conservation.

Phylogenomics reveals the evolutionary timing and pattern of butterflies and moths

Butterflies and moths (Lepidoptera) are one of the major superradiations of insects, comprising nearly 160,000 described extant species. As herbivores, pollinators, and prey, Lepidoptera play a fundamental role in almost every terrestrial ecosystem. Lepidoptera are also indicators of environmental change and serve as models for research on mimicry and genetics. They have been central to the development of coevolutionary hypotheses, such as butterflies with flowering plants and moths' evolutionary arms race with echolocating bats. However, these hypotheses have not been rigorously tested, because a robust lepidopteran phylogeny and timing of evolutionary novelties are lacking. To address these issues, we inferred a comprehensive phylogeny of Lepidoptera, using the largest dataset assembled for the order (2,098 orthologous protein-coding genes from transcriptomes of 186 species, representing nearly all superfamilies), and dated it with carefully evaluated synapomorphy-based fossils. The oldest members of the Lepidoptera crown group appeared in the Late Carboniferous (∼300 Ma) and fed on nonvascular land plants. Lepidoptera evolved the tube-like proboscis in the Middle Triassic (∼241 Ma), which allowed them to acquire nectar from flowering plants. This morphological innovation, along with other traits, likely promoted the extraordinary diversification of superfamily-level lepidopteran crown groups. The ancestor of butterflies was likely nocturnal, and our results indicate that butterflies became day-flying in the Late Cretaceous (∼98 Ma). Moth hearing organs arose multiple times before the evolutionary arms race between moths and bats, perhaps initially detecting a wide range of sound frequencies before being co-opted to specifically detect bat sonar. Our study provides an essential framework for future comparative studies on butterfly and moth evolution.

A cellular sound-absorbing metasurface with subwavelength thickness

The sound absorbing metasurface efficient in the audible frequency range is proposed. The metasurface has a cellular structure, each cell having a hexagonal shape with a hollow tunnel inside. The wall of the hexagonal cell is sub-divided into six hollow chambers connected to the central tunnel via the six thinner channels of different diameters. The hollow chambers act as Helmholtz resonators providing six different resonant frequencies for each cell. The negative effective bulk modulus property of the metasurface allows full adsorption at the resonant frequencies. By carefully designing the size of the connecting channels we can manipulate the desired sound adsorption frequency range. The thickness of the metasurface is in the range of 0.03–0.1 wavelengths for the sound frequency range between 300 and 1000 Hz. Six absorption peaks are achieved for each unit cell providing broader range of absorption. The hexagonal shape of the unit cell allows full utilization of the metasurface volume by a standard honeycomb tessellation of the cells. By designing a metasurface containing individual cells with different inner channel diameters, the absorption peaks can be multiplied or overlapped and further broaden the frequency range with the absorption coefficient higher than the desired value.

Technique of Informative Features Selection in Geoacoustic Emission Signals

Studies of geoacoustic emission in a seismically active region in Kamchatka show that geoacoustic signals produce pronounced pulse anomalies during the earthquake preparation and post-seismic relaxation of the local stresses field at the observation point. The qualitative selection of such anomalies is complicated by a strong distortion and weakening of the signal amplitude. A review of existing acoustic emission analysis methods shows that most often researchers turn to the analysis of more accessible to study statistical properties and energy of signals. The distinctive features of the approach proposed by the authors are the extraction of informative features based on the analysis of time and frequency-time structures of geoacoustic signals and the description of various forms of recognizable pulses by a limited pattern set. This study opens up new ideas to develop methods for detecting anomalous behavior of geoacoustic signals, including anomalies before earthquakes.&#x0D; The paper describes a technique of information extraction from geoacoustic emission pulse streams of sound frequency range. A geoacoustic pulse mathematical model, reflecting the signal generation process from a variety of elementary sources, is presented. A solution to the problem of detection of geoacoustic signal informative features is presented by the means of description of signal fragments by the matrixes of local extrema amplitude ratios and of interval ratios between them. The result of applying the developed algorithm to describe automatically the structure of the detected pulses and to form a pattern set is shown. The patterns characterize the features of geoacoustic emission signals observed at IKIR FEB RAS field stations. A technique of reduction of the detected pulse set dimensions is presented. It allows us to find patterns similar in structure. A solution to the problem of processing of a large data flow by unifying pulses description and their systematization is proposed. A method to identify a geoacoustic emission pulse model using sparse approximation schemes is suggested. An algorithmic solution of the problem of reducing the computational complexity of the matching pursuit method is described. It is to include an iterative refinement algorithm for the solution at each step in the method. The results of the research allowed the authors to create a tool to investigate the dynamic properties of geoacoustic emission signal in order to develop earthquake prediction detectors.