Search

Local ductwork components, such as shunt T-elbows, generate aerodynamic noise in ventilation and air-conditioning systems where turbulent air flow dissipates pulsation. The noise generated by airflow propagates along the ductwork to the end that terminates into a room. The incident acoustic energy may affect the working efficiency and health of the occupants. In this study, computational fluid dynamics and acoustic finite element methods were used to solve the Lighthill acoustic equation and simulate the flow field through T-elbows and the noise field generated by the airflow. The goal is to explore generation and transmission of aerodynamic noise through ductwork in a ventilation and air-conditioning system. The effects of inflow velocity, flow distribution ratio and T-elbow geometry on the noise intensity and acoustic energy propagation were investigated. The results show that low-frequency noises at the branch of the T-elbow are dominant and are caused by local unsteady vortex motion when the air flow diverges rapidly. In addition, the noise intensity and the propagated acoustic energy vary with the inflow velocity, branch flow rate ratio and branch geometry. Finally, the optimal structure for reducing noise in specific conditions can be determined by analysing and comparing various T-elbow geometries. [ABSTRACT FROM AUTHOR]

Purpose: Magnetic resonance acoustic radiation force imaging (MR‐ARFI) enables focal spot localization during nonablative transcranial ultrasound therapies. As the acoustic radiation force is proportional to the applied acoustic intensity, measured MR‐ARFI displacements could potentially be used to estimate the acoustic intensity at the target. However, variable brain stiffness is an obstacle. The goal of this study was to develop and assess a method to accurately estimate the acoustic intensity at the focus using MR‐ARFI displacements in combination with viscoelastic properties obtained with multifrequency MR elastography (MRE). Methods: Phantoms with a range of viscoelastic properties were fabricated, and MR‐ARFI displacements were acquired within each phantom using multiple acoustic intensities. Voigt model parameters were estimated for each phantom based on storage and loss moduli measured using multifrequency MRE, and these were used to predict the relationship between acoustic intensity and measured displacement. Results: Using assumed viscoelastic properties, MR‐ARFI displacements alone could not accurately estimate acoustic intensity across phantoms. For example, acoustic intensities were underestimated in phantoms stiffer than the assumed stiffness and overestimated in phantoms softer than the assumed stiffness. This error was greatly reduced using individualized viscoelasticity measurements obtained from MRE. Conclusion: We demonstrated that viscoelasticity information from MRE could be used in combination with MR‐ARFI displacements to obtain more accurate estimates of acoustic intensity. Additionally, Voigt model viscosity parameters were found to be predictive of the relaxation rate of each phantom's time‐varying displacement response, which could be used to optimize patient‐specific MR‐ARFI pulse sequences. [ABSTRACT FROM AUTHOR]

Ultra-short laser filamentation has been intensively studied due to its unique optical properties for applications in the field of remote sensing and detection. Although significant progress has been made, the quality of the laser beam still suffers from various optical aberrations during long-range transmission. Astigmatism is a typical off-axis aberration that is often encountered in the off-axis optical systems. An effective method needs to be proposed to suppress the astigmatism of the beam during filamentation. Herein, we numerically investigated the impact of the nonlinear effects on the focusing properties of the astigmatic Gaussian beams in air and obtained similar results in the experiment. As the single pulse energy increases, the maximum on-axis intensity gradually shifted from the sagittal focus to the tangential focus and the foci moved forward simultaneously. Moreover, the astigmatism could be suppressed effectively with the enhancement of the nonlinear effects, that is, the astigmatic difference and the degree of beam distortion were both reduced. Through this approach, the acoustic intensity of the filament (located at the tangential focal point) increased by a factor of 22.8. Our work paves a solid step toward the practical applications of the astigmatism beam as the nonlinear lidar. [ABSTRACT FROM AUTHOR]

This paper presents the experimental validations of reconstructing the characteristics of the excitation forces that act inside a vibrating structure, which includes the location, type, amplitude, and spectrum, based on a single set of measurements of the normal surface velocity on the exterior surface by using the modified Helmholtz Equation Least Squares (HELS) method, as if one could see through this solid structure. Phase I of this paper shows the reconstruction of the vibroacoustic responses in the exterior region of the structure, including the field acoustic pressure, the surface acoustic pressure, the normal surface velocity or Operational Deflection Shape (ODS), the normal component of the time-averaged acoustic intensity, and the time-averaged acoustic power. Phase II of this paper illustrates the reconstruction of the excitation forces with the fluid-loading effects taken into consideration, based on the vibroacoustic responses reconstructed in the exterior region. The significance of the study, namely, the interrelationships among the excitation force, structural vibration, and acoustic radiation is discussed. The knowledge thus acquired may be important for engineers to analyze various complex noise and vibration issues in practice and to come up with the most cost-effective noise and vibration mitigation strategies. [ABSTRACT FROM AUTHOR]

Acoustic emission (AE) detection through a liquid medium is a simple and effective method that can be widely applied to AE diagnosis for rotating machinery. As AE diagnosis is performed by correlating the signal intensity with the failure level and the frequency characteristics with the failure type, it is important to clarify the propagation characteristics of AE waves in liquid media to enable accurate AE diagnosis using a simpler system that utilizes AE propagation in a liquid medium. Therefore, in this study, systematic experiments were conducted focusing on the liquid medium type and the propagation distance as factors affecting the propagation characteristics of AE waves. As the area where AE waves propagate, we mainly focused on the near-field, where AE waves do not spread and are not attenuated with the propagation distance. First, we investigated the propagation and attenuation characteristics of AE waves in the near-field using an artificial AE source in liquid media such as purified water, cutting fluid solution, and lubricating oil. Differences in attenuation characteristics with the liquid medium were observed. Moreover, the propagation distance affected the attenuation characteristics, i.e., the signal intensity decreased with increasing propagation distance in a manner depending on the viscosity of the liquid medium, especially in the frequency bandwidth range from 1.5 to 3.0 MHz. Second, we theoretically verified some of the experimental results from the viewpoint of ultrasonic propagation in a liquid medium. As a result, the observed differences in attenuation characteristics with liquid medium were explained by the acoustic impedances of the liquid media, and the attenuation of the signal intensity of AE waves with increasing propagation distance was caused by the increasing absorption coefficient with increasing viscosity of the liquid medium. • Evaluation of propagation characteristics of acoustic emission waves propagating in liquid media. • Propagation distance and liquid medium type affect propagation characteristics. • Viscosity of the liquid medium affect the signal intensity of acoustic emission waves above 1.5 MHz. [ABSTRACT FROM AUTHOR]

Scaling industrial applications of the ultrasonic melt treatment (UMT) method for refining the solidification microstructure of metals has faced challenges, despite being proposed decades ago. A significant bottleneck is the need for a rapid pre-estimation of refinement. In this study, we present a semiquantitative model that facilitates this estimation. The model overcomes the time-consuming computations associated with dynamic cavitation regions by introducing a representative zone and extends its applicability by employing the empirical classic homogeneous theory for nucleation quantification. A case study involving aluminum alloys reveals an important finding: The refining efficiency of UMT peaks at approximately 120–140 MW/m2 within an acoustic intensity range of 0–150 MW/m2. Increasing the intensity beyond 150 MW/m2 does not significantly enhance efficiency. This work addresses the engineering need for a quick pre-estimation of microstructure refinement via UMT and promotes diverse applications by further exploring the method. [ABSTRACT FROM AUTHOR]

Passive acoustic thermometry (PAT), a method proposed for medical applications, involves direct measurement of the acoustobrightness temperature which is the intensity of the thermal acoustic radiation expressed in degrees. The hypothesis has been proposed that the acoustobrightness temperature measured on the surface of the object under study obeys the 2D heat equation whose parameters coincide or are uniquely connected with the parameters of the 3D heat equation governing the deep temperature of the object. Since in PAT a noise signal is measured, the achievement of an acceptable error level (0.5–1 K) requires a considerable integration time (about a minute). The proposed hypothesis will enable linking together the data obtained by acoustothermometric sensors separated in space, at different points in time. This, in turn, will lower the dimensionality of the problem of temperature distribution reconstruction and enable reducing the integration time without loss of accuracy. The proposed hypothesis has been confirmed experimentally and with the aid of computer simulation for the case where local hyperthermia of soft tissues of the human organism is modeled. [Display omitted] • Hypothesis: acoustobrightness temperature satisfies the 2D heat equation. • The equation's parameters are determined by the 3D heat equation for deep temperature. • The hypothesis was confirmed both numerically and experimentally. [ABSTRACT FROM AUTHOR]

A photoacoustic spectroscopy (PAS) based on vertical cruciform multi-stepped photoacoustic cell (CMS-PAC) was developed to achieve highly sensitive detection of trace acetylene (C 2 H 2) gas. Compared with the T-type PAC, the CMS-PAC has improved sensitivity through optimization of both the structural design and the direction of laser incidence. Through finite element simulation analysis, when the incidence direction of modulated laser was placed horizontally, the acoustic intensity of the CMS-PAC was ∼2.45 times higher than that of the T-type PAC. When the modulated laser was applied vertically, the acoustic intensity achieved by the CMS-PAC was ∼11 times higher than that along the horizontal incidence direction. The sensitivities of the CMS-PAC-based PAS system have reached 15.06 and 1.83 pm/ppm, along the vertical and horizontal directions, respectively. Combined with assessment using Allan deviation, the CMS-PAC-based PAS system achieved a minimum detection limit of 3.04 ppb@100 s in the vertical direction, and 23.06 ppb@100 s in the horizontal direction. The proposed CMS-PAC not only enhances acoustic intensity through optimized resonant cavity structures but also improves detection sensitivity with the optimized direction of laser incidence, providing a novel perspective for designing highly sensitive and compact PACs. • We propose a vertical cruciform multi-stepped photoacoustic cell. • There are two directions of laser incidence perpendicular to each other. • The proposed new photoacoustic cell has advantages of compact size. • The proposed new photoacoustic cell has better detection sensitivity. [ABSTRACT FROM AUTHOR]

• Combining hydrodynamic and acoustic cavitation significantly enhances the energy-efficient processing of cellulose fibers. • Achieving maximum efficiency requires extensive optimization through multiphysical simulations and experimental investigations to understand the interaction of physical phenomena. • Effective sonicator design requires tuning of sonotrodes, signals, structural geometry, fluid volumes, flow conditions, and nozzle design to achieve synchronized resonance amplification at high power. • Cavitation treatment gives a notably improved fiber properties at specific concentrations, temperatures when combined with proper acoustic and hydrodynamic cavitation intensities. The cellulose pulp refining process is crucial for achieving high-quality paper characteristics. This research aims to enhance energy efficiency while maintaining good fiber quality using hydrodynamic and acoustic cavitation (HAC). Experiments were conducted with an in-house developed flow-through sonicator combined with a novel Venturi nozzle for hydrodynamic cavitation. The Venturi design was determined by analytical modeling and verified by CFD simulation with multi-phase turbulence models to balance cavitation intensity and turbulence against the acoustic cavitation effect. Experimental evaluation of two batches of CTMP fibers, pre-processed in different ways, showed significant improvements in paper strength and fiber properties. The best results for Batch 1 (HC and LC) were obtained with 386 kWh/bdt for AC and 350 kWh/bdt for HC (60 °C, 2 % concentration). The tensile strength index increased by 26 %, and the TEA-index, related to freeness, increased by 55 %. HAC treatment (750 kWh/bdt, 70 °C, 1.5 % concentration) of the less refined Batch2 (HC) yielded results better than the Batch 1 reference. These findings confirm the energy-efficient potential of the sonicator concept compared to traditional industrial processes. The conclusion is that HAC-refining of softwood pulp requires a proper balance between hydrodynamic and acoustic cavitation intensities. Both fiber concentration by weight and temperature are critical for an energy-efficient process. [Display omitted] [ABSTRACT FROM AUTHOR]

This work explores strategies to change the directivity of sound radiated from an oscillating metamaterial plate. To this end, the vibro-acoustic behavior of a plate that hosts an array of piezoelectric unit cells, whose inductive shunt resonance frequencies can assume different predefined configurations in space, is numerically investigated. The effects of such configurations on (i) the structural normal velocity of the plate, (ii) the hemispherical acoustic field estimated based on Rayleigh's integral, and (iii) the non-negative acoustic intensity are discussed. The numerical results show that simple changes in the unit cell's tuning configuration in space can reduce, totally attenuate, or enhance the sound radiated in specific directions, findings that may pave the way to the use of reconfigurable metamaterials as effective systems for selective radiated noise directivity. [Display omitted] • The vibro-acoustic behavior of a piezoelectric metamaterial plate is investigated. • The acoustic model is a locally resonant metastructure bounded by an infinite baffle. • Changes in the unit cell's configuration affect the radiated sound directivity. [ABSTRACT FROM AUTHOR]

A model-based analysis of sound transmission in a deep ice-covered Arctic ocean recorded during the Ice Experiment 2014 is presented. A source of opportunity transmitted mid-frequency (3500 Hz) 5 s duration continuous wave pulses. The source and receiver were omnidirectional, located under ice at a ∼30 m depth at a ∼719 m distance from each other. Recorded acoustic intensity time series showed a clear direct blast signal followed by an about 30 s duration reverberation coda. The model considers several types of arrivals contributing to the received signal at different time intervals. The direct signal, corresponding to a short-range nearly horizontal propagation, is strongly affected by the presence of a weak near-surface (within 50 m depth) acoustic channel. Reverberation coda that follows the direct signal corresponds to medium-range bottom- and ice-bounced arrivals from steep angles which are controlled by reflectivity and scattering strengths of ice and bottom, their physical properties, and acoustical parameters. [ABSTRACT FROM AUTHOR]

In this paper, we attempt to unify two array processing frameworks viz, Acoustic Vector Sensor (AVS) and two level nested array to enhance the Degrees of Freedom (DoF) significantly beyond the limit that is attained by a Uniform Linear Hydrophone Array (ULA) with specified number of sensors. The major focus is to design a line array architecture which provides high resolution unambiguous bearing estimation with increased number of spatial nulls to mitigate the multiple interferences in a deep ocean scenario. AVS can provide more information about the propagating acoustic field intensity vector by simultaneously measuring the acoustic pressure along with tri-axial particle velocity components. In this work, we have developed Nested AVS array (NAVS) ocean data model to demonstrate the performance enhancement. Conventional and MVDR spatial filters are used as the response function to evaluate the performance of the proposed architecture. Simulation results show significant improvement in performance viz, increase of DoF, and localization of more number of acoustic sources and high resolution bearing estimation with reduced side lobe level. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Tikrit University for Humanities is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Problems of Friction & Wear is the property of National Aviation University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents analyses of the 3D acoustic fields generated by motorcycles at very low frequencies (< 1 5 0 Hz) at the idle speed and during sudden acceleration. Diagnosis and analyses of sound sources at low frequencies have always been a significant challenge because the directivity of low-frequency sound is very poor. To date, there are no research papers and/or reports that have demonstrated low-frequency sources localization and radiation patterns of any kind at high spatial resolution in 3D space. This study shows that by using sound viewer technologies, which include the passive sonic detection and ranging (SODAR), the Helmholtz equation least squares (HELS) method, advanced signal processing, denoising, etc., the locations of sound sources and visualization of the sound fields can be determined with high spatial resolution, even at frequencies below 150 Hz. In particular, the HELS method allows for reconstructing all the acoustic quantities, including the acoustic pressure, time-averaged acoustic intensity, time-averaged acoustic power on the source surfaces and in 3D space. The hardware needed consists of a 3D array with six free-field precision microphones with pre-amplifiers, a miniature wide-angle camera, an eight-channel digital signal processor and a laptop computer. [ABSTRACT FROM AUTHOR]

The phase and amplitude gradient estimator (PAGE) method [Thomas, Christensen, and Gee, J. Acoust. Soc. Am. 137, 3366–3376 (2015)] has been developed as an alternative to the traditional p-p method for calculating energy-based acoustic measures such as active acoustic intensity. While this method shows many marked improvements over the traditional method, such as a wider valid frequency bandwidth for broadband sources, contaminating noise can lead to inaccurate results. Contaminating noise degrades performance for both the traditional and PAGE methods and causes probe microphone pairs to exhibit low coherence. When coherence is low, better estimates of the pressure magnitude and gradient can be obtained by using a coherence-based approach, which yields a more accurate intensity estimate. This coherence-based approach to the PAGE method, known as the CPAGE method, employs two main coherence-based adjustments. The pressure magnitude adjustment mitigates the negative impact of uncorrelated contaminating noise and improves intensity magnitude calculation. The phase gradient adjustment uses coherence as a weighting to calculate the phase gradient for the probe and improves primarily the calculation of intensity direction. Though requiring a greater computation time than the PAGE method, the CPAGE method is shown to improve intensity calculations, both in magnitude and direction. [ABSTRACT FROM AUTHOR]

In food application, nano-zinc oxide (nano-ZnO) is a very important nano metal material; thus, it is necessary to prepare potentially food-grade nano-ZnO. Nano-ZnO synthesized by the ultrasound-assisted method can reach a safe level because of its import physical processing characteristics. Firstly, the micromorphology and microstructure of nano-ZnO synthesized by the ultrasonic method were compared with that by the mechanical stirring method through atomic force microscopy, X-ray diffraction, and Fourier-transform infrared. Secondly, the on-line monitoring of different ultrasonic fields in real-time was studied during the whole synthesis process of nano-ZnO by polyvinylidene fluoride sensor, and two control groups (water medium) were set. The results showed that nano-ZnO obtained by the ultrasonic method were smaller in size and had less surface roughness compared with the mechanical stirring method. The nucleation and crystallization process of nano-ZnO was controlled by the ultrasonic method with sharp diffraction peaks of higher intensities. Moreover, for the ultrasonic mechanism, it was found that the oscillation behavior of bubbles varied from liquid to liquid, and variation was also found in the same liquid under different restraint of interfaces. Based on voltage waveforms monitored in the three liquid media, differences in the life cycle of cavitation bubble oscillation, cycle of collapse stage, maximum voltage amplitude, and acoustic intensity were observed. The physical mechanism of ultrasound-assisted synthesis of nano-ZnO was revealed through voltage fluctuations of the acoustics signal, which can lay a theoretical foundation for the controllability of food ultrasonic physical processing. [ABSTRACT FROM AUTHOR]

Simple Summary: During annual periods of heightened sexual activity (musth), male African elephants expend a significant amount of energy communicating their reproductive status, as well as searching and competing for potential mates. To locate females, musth males may risk venturing outside protected areas and into landscapes shared with humans where conflict between wildlife and people can occur. Adverse interactions between elephants and people can be detrimental to human livelihoods, resulting in negative attitudes towards elephants and, in some cases, retaliatory killings. Interactions with aggressive musth males can also be life-threatening to community members who attempt to confront them. Mitigation strategies that effectively target the reproductive motivations of musth males may offer solutions as the human–elephant interface continues to expand. In this study, we build on earlier research showing that playbacks of female elephant reproductive calls, (i.e., estrous rumbles) can change the movement trajectory and behavior of male elephants in Etosha National Park, Namibia. Individuals belonging to three male groups were opportunistically subjected to playback experiments and evaluated based on their reaction intensity. Our results demonstrate that mature musth adults are more likely to change directions and approach the source of a female's estrous call than mature, sexually-inactive adult elephants. We also show that post-dispersal young males that were not in musth also respond strongly to the stimulus. These findings support further exploration of mitigation solutions that incorporate elephant behavior, reproductive status, and context-specific vocalizations. Driven by reproductive motives, male African elephants (Loxodonta africana) in musth often expand their home ranges to locate estrous females. This extended range, coupled with heightened aggression often observed in musth males, can be particularly problematic in regions where human-modified landscapes and elephant territories increasingly overlap. Several mitigation tools have been tested to resolve a wide range of human–elephant conflicts with varying degrees of success due to geographical disparities and habituation. We present findings on the potential application of estrous call playbacks in manipulating the behavior and movement of male elephants non-invasively, particularly mature musth adults and younger post-dispersal males, in Etosha National Park. Estrous vocalizations were presented across 26 experimental trials to mature musth adults (n = 5), mature non-musth adults (n = 6), and non-musth males belonging to younger, post-dispersal age classes (n = 8), with behavioral responses scored on a gradient scale from 0–1. Both mature musth adults and younger non-musth elephants were significantly more likely to respond with the highest intensity by approaching the acoustic source compared to mature non-musth adults that avoided the call. However, younger males tested in the presence of an older, higher-ranking male tended to react with a lower intensity than those tested alone. This result likely demonstrates the influence of social hierarchy and associations on male elephant behavior. We also observed a significant increase in physiological response, measured by defecation rate, across all male groups in response to the estrous call playbacks. Our findings suggest that using estrous calls as acoustic deterrents may effectively and non-invasively aid in reducing tension at the human–elephant interface, depending on the age, social context, and reproductive status of the male elephant. [ABSTRACT FROM AUTHOR]

This study was aimed at evaluating the feasibility, safety and therapeutic effects of high-intensity focused ultrasound ablation (HIFUA) in the treatment of post-operative recurrent desmoid tumors. From September 2017 to May 2020, 42 consecutive patients with pathologically proven desmoid tumors treated with HIFUA for the first time were enrolled. These were divided into two groups: post-operative recurrent group (30 cases) and non-surgery group (12 cases). The basic characteristics, treatment parameters, ablation efficacy, tolerance and adverse events were recorded and compared between groups. The minimum distance between the tumor and skin surface in the post-operative recurrent group was significantly smaller than that in the non-surgery group (6.9 mm vs. 10.8 mm, p = 0.011), but there was no significant difference in the other basic characteristics (p > 0.05). The average acoustic power and intensity of treatment in the post-operative recurrent group were significantly lower than those in the non-surgery group (p = 0.006 and 0.036, respectively), but there was no significant difference in the remaining parameters or in ablation efficacy between groups (p > 0.05). HIFUA was successfully performed, and a large volume of coagulation necrosis was obtained from all patients without serious or life-threatening adverse events. Furthermore, there was no significant difference in the incidence of moderate adverse events and average length of stay between groups (p > 0.05). The average power and intensity of HIFUA treatment were adversely affected by surgical scar and tumor infiltration along the surgical path. However, HIFUA can still be used as an effective minimally invasive therapy for the local control of post-operative recurrent desmoid tumors. [ABSTRACT FROM AUTHOR]

We report an experiment to investigate possible vestibular effects on finger tapping to an auditory anapaest rhythm. In a sample of 10 subjects, index finger acceleration and tapping force were recorded along with extensor/flexor activity and the associated electroencephalographic activity measured at central and cerebellar surface electrodes. In a prior session with a standard short air-conducted 500-Hz pip, vestibular evoked myogenic potential thresholds were measured and subsequently used to set the acoustic intensity. During the main experiment subjects were asked to synchronise tapping to the pips arranged in the anapaest at two different frequencies, 500 Hz vs 5 kHz, so that only the low-frequency high-intensity condition was a vestibular, as well as an auditory stimulus. We hypothesised that a vestibular effect would manifest in an interaction between the frequency and intensity factors for a range of dependent measures of tapping performance. No clear evidence was found for vestibular effects, but this was likely due to the confounding effects of an independent effect of intensity and the relative weakness of the acoustic vestibular stimulus. However, the data did show novel evidence for two distinct timing processes for the flexion and extension stages of a tap cycle and two distinct timing strategies, which we refer to as 'staccato' and 'legato', characterised by different profiles of force and extension. [ABSTRACT FROM AUTHOR]

The acoustic vector sensor (AVS) is used to measure the acoustic intensity, which gives the direction-ofarrival (DOA) of an acoustic source. However, while estimating the DOA from the measured acoustic intensity the finite microphone separation (d) in a practical AVS causes angular bias. Also, in the presence of noise there exists a trade off between the bias (strictly increasing function of d) and variance (strictly decreasing function of d) of the DOA estimate. In this paper, we propose a novel method for mitigating the angular bias caused due to finite microphone separation in an AVS. We have reduced the variance by increasing the microphone separation and then removed the bias with the proposed bias model. Our approach employs the finite element method (FEM) and curves fitting to model the angular bias in terms of microphone separations and frequency of a narrowband signal. Further, the bias correction algorithm based on the intensity spectrum has been proposed to improve the DOA estimation accuracy of a broadband signal. Simulation results demonstrate that the proposed bias correction scheme significantly reduces the angular bias and improves the root mean square angular error (RMSAE) in the presence of noise. Experiments have been performed in an acoustic full anechoic room to corroborate the effect of microphone separation on DOA estimation and the efficacy of the bias correction method. [ABSTRACT FROM AUTHOR]

The first evidence of the existence of a bottom nepheloid layer in the Kane Gap (Central East Atlantic) was obtained from acoustic backscattering data. It was located within the transformed Antarctic Bottom Water and was 150 m thick. The high velocities of bottom currents in the Gap suggest the permanence of the bottom nepheloid layer. The detailed structure of the vertical distribution of Antarctic Bottom Water tracers – oxygen and mineral silicate– has been revealed. Large biomineral aggregates (~40 μm) were found in the bottom suspended matter of the Kane Gap. They form in the highly productive North African upwelling area and are rapidly deposited to the ocean bottom layer due to ballasting of gel-like phytoplankton products by dense mineral particles from the Sahara Desert. Surface and bottom currents carry the suspended sediment aggregates to Kane Gap. [ABSTRACT FROM AUTHOR]

Acoustic emissions in directed energy deposition processes such as wire arc additive manufacturing and directed energy deposition with laser beam/metal are investigated within this work, as many insights about the process can be gained from this. In both processes, experienced operators can hear whether a process is running stable or not. Therefore, different experiments for stable and unstable processes with common process anomalies were carried out, and the acoustic emissions as well as process camera images were captured. Thereby, it was found that stable processes show a consistent mean intensity in the acoustic emissions for both processes. For wire arc additive manufacturing, it was found that by the Mel spectrum, a specific spectrum adapted to human hearing, the occurrence of different process anomalies can be detected. The main acoustic source in wire arc additive manufacturing is the plasma expansion of the arc. The acoustic emissions and the occurring process anomalies are mainly correlating with the size of the arc because that is essentially the ionized volume leading to the air pressure which causes the acoustic emissions. For directed energy deposition with laser beam/metal, it was found that by the Mel spectrum, the occurrence of an unstable process can also be detected. The main acoustic emissions are created by the interaction between the powder and the laser beam because the powder particles create an air pressure through the expansion of the particles from the solid state to the liquid state when these particles are melted. These findings can be used to achieve an in situ quality assurance by an in-process analysis of the acoustic emissions. [ABSTRACT FROM AUTHOR]

Pig carcasses have been used in forensic research because they share several similarities to human cadaver, including decomposition. In several studies, the decomposition of pig's cadaver for a certain time can be used as a model to determine the time of death of a human. This study was conducted to determine the relationship between the days of spoilage of pig tissue and the level of average sound intensity produced by the sample. Then, in this study, pig skeletal muscles were allowed to decay with a variation of 1-5 days. Afterward, these muscles were imaged using diode laserbased photoacoustic tomography. Results of the experiment show that the average acoustic intensity level from the first day until the fourth day has increased (78-92 a.u for young pig and 76-86 a.u for old pig) but decreased on the fifth day (88 a.u for young and 84 a.u for old pig). These results can improve forensic imaging because such results can be applied to determine the time of death of human by plotting the ratio of the average sound intensity level of the sample to the number of days of decomposition. [ABSTRACT FROM AUTHOR]

Although near-field acoustical holography (NAH) and acoustic intensity analysis have previously been used to investigate the apparent jet noise sources produced by military aircraft, explicit connections to supersonic jet characteristics cannot be made due to a lack of information about the exhaust plume. To begin to bridge this gap and better understand the source information yielded by NAH, the current study instead applies NAH to a virtual measurement of the near-field pressures of a highly heated laboratory-scale supersonic jet generated by large-eddy simulation (LES). The holographic reconstructions of the pressure, particle velocity, and acoustic intensity are found to match the LES-generated acoustic field well and are used to calculate the acoustic power of the jet. The jet's calculated overall acoustic power is compared to the free-stream mechanical power, resulting in an acoustic efficiency of 1.5%. Ray-tracing of the acoustic intensity to the jet centerline generates an axial distribution of the acoustic power origin, showing that almost all the power originates from the supersonic portion of the flow and with the distribution peak upstream of the potential core tip. Holographic reconstruction of the pressures along the nozzle lipline captures the general spectral shape of the LES-generated pressures, though it underestimates the amplitude. [ABSTRACT FROM AUTHOR]

During an experiment conducted in the deep South China Sea, a bottom-mounted horizontal linear array (HLA) collected the radiated noise from a moving cooperative ship at a distance less than 13 km. Bearing-time records of the HLA through plane-wave beamforming showed significant bearing estimation errors and two or three split bearing tracks of the ship that leads to misjudgment of target numbers. To reveal the physics underlying the experimental phenomena, the directional response of the HLA to an acoustic source at close range was developed by normal mode theory. Numerical simulations were conducted to analyze the acoustic intensity distribution characteristics and the arrival structures of the acoustic field. Comparative results of beamforming obtained with normal mode and ray theory show that the ray model provides an easy way to predict the split bearings for HLA beamforming. When sources are near the endfire of the array, significant bearing estimation errors and the beam splitting effect for a large aperture array were the main issues. For sources near the broadside of the array, the beam broadening effect was the most significant concern. The effect of the array length on the beamforming anomalies and the array gain loss was also investigated. With the present theories, the HLA beamforming anomalies during the experiment were well explained. [ABSTRACT FROM AUTHOR]

Implementation of remote monitoring technology for real wind turbine structures designed to detect potential sources of failure is described. An innovative multi-axis contactless acoustic sensor measuring acoustic intensity as well as previously known accelerometers were used for this purpose. Signal processing methods were proposed, including feature extraction and data analysis. Two strategies were examined: Mel Frequency Cepstral Coefficients pruned with principal component analysis and autoencoder-based feature extraction. The scientific experiment resulted in data gathering and analysis to predict potential wind turbine mechanism failures.

The excitation of the transverse acoustic modes of a duct by the flow around rectangular rods with sharp corners is experimentally investigated. Emphasis is given to the unique role of the rod's flow incidence angle and its cross section aspect ratio on the flow structure and its susceptibility to resonance excitation. Two different mechanisms that lead to acoustic resonance excitation are identified. The first mechanism is triggered by the vortex shedding observed downstream of the square rod regardless of its aspect ratio. The second mechanism is triggered by the interaction of the separated shear layers from the rod's upstream corners with the rod's trailing edges, and it results in an abrupt excitation of the third acoustic cross-mode at conditions that depend on the side length of the rod. Moreover, the excitation of this mechanism occurs at lower flow velocities than those required to excite the first acoustic mode, which is not the case for circular cylinders in cross-flow. The Strouhal number and the symmetry of the vortex shedding from the square rod have profound dependence on the rod's aspect ratio and its flow incidence angle, which, in turn, affect the amplitude of the excited acoustic pressure and the lock-in velocity range. Asymmetric vortex shedding can alleviate the intensity of acoustic resonance, where the minimum acoustic pressure occurs close to an incidence angle of 9 ∘ . However, this reduction should be carefully considered as rods at low flow incidence angles may excite resonance of higher-order acoustic cross-modes at lower flow velocities over a wider lock-in range. [ABSTRACT FROM AUTHOR]

In this work, by using the wave equations proposed by the authors for the vector of the vibrational velocity of particles and the well-known equation for acoustic pressure in an inhomogeneous stationary medium, the influence of the parameters of the medium on the vector-phase properties of the acoustic field is investigated. For the first time, analytical equations are found for the phases and moduli of the vectors of the complex intensity and acoustic energy flux density (acoustic intensity vector), vibrational velocity, pressure, and energy density, which establish a relation between them and both the medium density and the speed of sound. The proposed approach allows an analytical analysis of the influence of the density of and speed of sound in an inhomogeneous medium on the parameters of the acoustic field. In turn this approach opens possibilities of solving the reciprocal problem on finding the spatial distribution of the density and the speed of sound of a medium on the basis of measured values of the acoustic pressure and the vibrational velocity. [ABSTRACT FROM AUTHOR]

This report describes the generation of acoustic signals via laser-interference-based heating. Sound signals of varying intensities were generated by modulating two continuous-wave (CW) laser beams interfering in air. In this study, we discovered that the acoustic signals generated by two spatial-frequency-modulated CW lasers scanning in air are significantly stronger than those of a single CW laser. The intensity of photoacoustic signals is proportional to the diameter of the laser beam. Furthermore, our investigation showed that modulating the spatial frequency of the two laser beams can change the intensity of the acoustic signal. In addition, we found that the two beams stack better against a single beam when scanned vertically in three dimensions. [ABSTRACT FROM AUTHOR]

The usage of wood as an environmentally friendly material combines optimized room aesthetics with mechanical and/or acoustic functionality. Cellular materials like wood play an important role in reducing vibration and noise. It is considered to have low damping properties due to its molecular structure and its relatively high modulus of elasticity. This property is well known to musical instrument makers and is accordingly taken into consideration in the manufacture of such instruments. Site-specific, targeted wooden cladding can help to dampen vibrations. Against the background of noise and vibration control, wooden plates in the form of connected bodies are often used, e.g. to build an enclosure. The vibration behaviour of the resonance body of a wooden musical instrument is difficult to determine. In this context, basic acoustic investigations into the radiation efficiency of wooden panels become mandatory. The solutions to the equation of motion of the vibrating plate depend, among others, on the geometry of the plate and the conditions of its clamping. A fact that makes it very challenging to predict is e.g. eccentric load application that causes much more natural vibrations. In this paper, a plate made of the tonewood spruce was mechanically excited in the centre on the back. The acoustic intensity of the panel on the other side was then measured as a spatial function using an acoustic sensor. Since the clamping conditions influence the vibration characteristics, the measurements were conducted under different clamping loads. A relatively stable mode pattern emerged that was more pronounced at the highest clamping load. [ABSTRACT FROM AUTHOR]

Purpose: Focused ultrasound (FUS) is a promising tool to develop new modalities of therapeutic neurostimulation. The ability of FUS to stimulate the nervous system, in a noninvasive and spatiotemporally precise manner, has been demonstrated in animals and human subjects, but the underlying biomechanisms are not fully understood yet. The objective of the present study was to investigate the bioeffects involved in the generation of trains of action potentials (APs) by repetitive‐pulse FUS stimuli in a simple invertebrate neural model. Methods: The respective influences of different acoustic parameters on the neurostimulation success rate (NSR), defined as the rate of FUS stimuli capable of evoking at least one AP, were explored using the system of afferent nerves and giant fibers of Lumbricus terrestris as neural model. Each parameter was studied independently by administering random FUS sequences while keeping all but one FUS parameter constant. The NSR was evaluated as a function of (i) the spatial‐average pulse‐average intensity (Isapa); (ii) the pulse duration (PD); (iii) the pulse repetition frequency (PRF); iv) the number of cycles per pulse (Ncycles); (v) two ultrasound frequencies, f0 = 1.1 MHz and f3 = 3.3 MHz, corresponding to the fundamental and third‐harmonic resonant frequencies of the FUS transducer, respectively (spherical, radius of curvature: 50 mm); and (vi) levels of emerging stable cavitation and inertial cavitation. Results: The NSR associated to 1.1 MHz repetitive‐pulse FUS stimuli was found to increase as a function of increasing Isapa, PD, PRF, and Ncycles. When evaluating each parameter at f = 1.1 MHz, it was observed that NSRs close to 100% were achieved when sufficiently elevating their respective values. When computing the NSR as a function of the spatial‐average, temporal‐average intensity (Isata), defined as the product of PRF, PD, and Isapa, a significant elevation of the NSR from 0% to close to 100% was measured by increasing Isata from values approximate to 4 W/cm2 to values higher than 12 W/cm2. No clear and consistent trend was observed in trials aimed at exploring the effects of different levels of stable and inertial acoustic cavitation on the NSR. Finally, the feasibility of inducing neural responses with 3.3 MHz repetitive‐pulse FUS stimuli was also demonstrated with NSRs reaching up to 60%, in the range of FUS parameters studied. Conclusion: The time‐averaged value of the radiation force per unit volume of tissue is proportional to the acoustic intensity. As a result, the observations from this study suggest that the neural structure responding to the stimulus is sensitive to the mean radiation force carried by the FUS sequence, regardless of the combination of FUS parameters giving rise to such force. The results from this study further revealed the existence of a minimal activation threshold with regard to Isapa. [ABSTRACT FROM AUTHOR]

The acoustic activity developed in marble specimens under various loading schemes is explored in terms of the recently introduced F-function. The novelty of the study is that instead of describing the temporal evolution of the F-function in terms of conventional time, the Natural Time concept is employed. Although completely different geometries and loading schemes were considered, the evolution of the F-function in the Natural Time domain exhibits a self-consistent motive: its values increase progressively with fluctuations of varying intensity, however, while the fracture is approaching, a power law appears to systematically govern the response of the specimen/structure loaded. The exponent of this law, somehow corresponding to the intensity of the acoustic activity within the loaded complex, varies within broad limits. The onset of validity of the power law designates that the system has entered into its critical stage, namely that of impending fracture, providing a useful pre-failure signal. [ABSTRACT FROM AUTHOR]

Ceasing an ongoing motor response requires action cancelation. This is impaired in many pathologies such as attention deficit disorder and schizophrenia. Action cancelation is measured by the stop signal task that estimates how quickly a motor response can be stopped when it is already being executed. Apart from human studies, the stop signal task has been used to investigate neurobiological mechanisms of action cancelation overwhelmingly in rats and only rarely in mice, despite the need for a genetic model approach. Contributing factors to the limited number of mice studies may be the long and laborious training that is necessary and the requirement for a very loud (100 dB) stop signal. We overcame these limitations by employing a fully automated home-cage-based setup. We connected a home-cage to the operant box via a gating mechanism, that allowed individual ID chipped mice to start sessions voluntarily. Furthermore, we added a negative reinforcement consisting of a mild air puff with escape option to the protocol. This specifically improved baseline inhibition to 94% (from 84% with the conventional approach). To measure baseline inhibition the stop is signaled immediately with trial onset thus measuring action restraint rather than action cancelation ability. A high baseline allowed us to measure action cancelation ability with higher sensitivity. Furthermore, our setup allowed us to reduce the intensity of the acoustic stop signal from 100 to 70 dB. We constructed inhibition curves from stop trials with daily adjusted delays to estimate stop signal reaction times (SSRTs). SSRTs (median 88 ms) were lower than reported previously, which we attribute to the observed high baseline inhibition. Our automated training protocol reduced training time by 17% while also promoting minimal experimenter involvement. This sensitive and labor efficient stop signal task procedure should therefore facilitate the investigation of action cancelation pathologies in genetic mouse models. [ABSTRACT FROM AUTHOR]

MicroRNA-mediated gene therapy is emerging as a promising method for the treatment of ovarian cancer, but the development of miRNA mimic delivery vectors is still in its infancy, where the safety and efficacy of miR-34a-mimic remain unknown. Ultrasound-targeted microbubble destruction (UTMD) can be an effective and minimally invasive tool for the delivery of miR-34a-mimic in vitro and in vivo. Here, we describe a high-efficiency gene delivery strategy by using miR-34a-mimic loaded folate modified microbubbles (miR-34a-FM) with a portable ultrasonic irradiation system. Ultrasonic parameters, including acoustic intensity (AI), exposure time (ET) and duty cycle (DC), were optimized and the optimal acoustic condition (1.0 W/cm², 20 s, and 15% DC) was used to deliver miRNA-34a into cells in vitro. MiR-34a mimic was successfully introduced into the cytoplasm and was found to inhibit proliferation and induce apoptosis of SK-OV-3 cells. Next, miR-34a-mimic was delivered to tumor tissue via UTMD, inhibiting tumor growth and prolonging the survival time of mice. In summary, UTMD-mediated miR-34a-mimic delivery has potential application in the clinical treatment of ovarian cancer. [ABSTRACT FROM AUTHOR]

Background and Aim: Contrast-enhanced ultrasound (CEUS) measures of post-occlusion skeletal muscle microvascular responsiveness demonstrate the microvascular dysfunction associated with ageing and age-related disease. However, the accessibility of CEUS is limited by the need for intravenous administration of ultrasound contrast agents and sophisticated imaging analysis. Alternative methods are required for the broader assessment of microvascular dysfunction in research and clinical settings. Therefore, we aimed to evaluate the level of association and agreement between CEUS and near-infrared spectroscopy (NIRS)-derived measures of post-occlusion skeletal muscle microvascular responsiveness in older adults.Methods: During supine rest, participants (n=15, 67±11 years) underwent 5 minutes of thigh cuff-occlusion (200 mmHg). Post-occlusion CEUS measures of calf muscle microvascular responsiveness were made, including time to 95% peak acoustic intensity (TTP95 AI) and the rate of rise (slope AI). Simultaneous measures, including time to 95% peak oxygenated haemoglobin (TTP95 O2Hb) and slope O2Hb, were made using continuous-wave NIRS in the same muscle region.Results: There were strong correlations between TTP95 measures derived from CEUS and NIRS (r=0.834, p=<0.001) and the corresponding measures of slope (r=0.735, p=0.004). The limits of agreement demonstrated by Bland Altman plot analyses for CEUS and NIRS-derived measures of TTP95 (-9.67-1.98 s) and slope (-1.29-5.23%. s-1) were smaller than the minimum differences expected in people with microvascular dysfunction.Conclusions: The strong correlations and level of agreement in the present study support the use of NIRS as a non-invasive, portable and cost-effective method for assessing post-occlusion skeletal muscle microvascular responsiveness in older adults. [ABSTRACT FROM AUTHOR]

• Frequency domain analysis of the acoustic signal of the vortex tube was conducted. • The sound energy is mainly concentrated in the frequency range of 4000-5000 Hz. • Higher inlet pressure tends to produce higher acoustic intensity. • Energy separation efficiency increases with the growth of the sound pressure level. • The vortex tube with 5 nozzles has the maximum coefficient of performance. The purpose of this paper is to study the acoustic signal characteristics of a Ranque-Hilsch vortex tube and discuss the energy separation phenomenon behind it. Experiments were conducted with air as the working fluid. The acoustic signal and corresponding thermal fluid parameters are measured. The influencing factors such as inlet pressure, nozzle number, and cold mass fraction were investigated. The results show that the acoustic energy of the vortex tube is chiefly within the range from 4000 Hz to 5000 Hz. Two frequency peaks (about 1500 Hz and 4200 Hz) are observed in the frequency domain. As the inlet pressure increases, the sound pressure level(SPL) increases, and as the cold mass fraction increases, the SPL decreases. There is a positive correlation between the sound intensity and the energy separation performance. Interestingly, the vortex tube with 5 nozzles produces maximum SPL and COP (Coefficient of performance) compared to the 4-nozzle and 6-nozzle vortex tubes. [ABSTRACT FROM AUTHOR]

The sources of noise and vibration of a refrigerator are characterized by means of laboratory measurements. Three different elements are considered: compressor, evaporator fan, and condenser fan. Both the radiated acoustic energy and the mechanical power injected to the refrigerator structure are measured. Acoustic intensity maps on the refrigerator faces at different frequencies are also provided They are helpful in visualizing the more problematic zones in terms of noise emission. The devices are tested invacuo or working inside the refrigerator. The provided information can be used as input data for vibroacoustic simulation models such as statistical energy analysis. It is also of interest in order to improve the refrigerator acoustic design. [ABSTRACT FROM AUTHOR]

Natural sounds, and bird song in particular, play a key role in building and maintaining our connection with nature, but widespread declines in bird populations mean that the acoustic properties of natural soundscapes may be changing. Using data-driven reconstructions of soundscapes in lieu of historical recordings, here we quantify changes in soundscape characteristics at more than 200,000 sites across North America and Europe. We integrate citizen science bird monitoring data with recordings of individual species to reveal a pervasive loss of acoustic diversity and intensity of soundscapes across both continents over the past 25 years, driven by changes in species richness and abundance. These results suggest that one of the fundamental pathways through which humans engage with nature is in chronic decline, with potentially widespread implications for human health and well-being. Birdsong has long connected humans to nature. Historical reconstructions using bird monitoring and song recordings collected by citizen scientists reveal that the soundscape of birdsong in North America and Europe is both quieter and less varied, mirroring declines in bird diversity and abundance. [ABSTRACT FROM AUTHOR]

The modern automotive industry invests more and more in electric drive technology. As a result, new challenges arise in terms of vibroacoustic optimization of the car interior. Components that were once masked by the internal combustion engine are starting to dominate the interior of vehicles. There is therefore a great need for noise reduction. For this purpose, a number of methods of its reduction are used, i.e. component optimization (source), use of active noise reduction systems or passive soundproofing materials. In order to perform the abovementioned noise reduction measures, appropriate measurements and signal analysis should be carried out. This presentation aims to present the measurement of an automotive air cooler in transient states on the stand. Measurements were made using a 3D intensity probe based on the direct measurement of the acoustic particle velocity, in 3 planes in front of the cooler. Then, order tracking analysis was performed for the run-up and coast-down. The results in the form of selected orders of intensity and acoustic particle velocity were compared with classical results made with the use of a microphone at the same measurement points locations. [ABSTRACT FROM AUTHOR]

This study documents periodic acoustic pulse generation by heat in a thermoacoustic oscillator system constructed from a gas-filled acoustic resonance tube having a porous medium called a stack. When the system's dissonancy was enhanced by a local cross-sectional area change in the resonance tube, the periodic pulsed state was turned to a quasiperiodic state. This observation suggests that the acoustic pulse was created through the mode-locking of internal oscillation modes. Propagation of pulsed acoustic intensity in the resonance tube was evidenced by simultaneous measurements of acoustic pressure and axial acoustic particle velocity of the gas. [ABSTRACT FROM AUTHOR]

The spatial and size distribution of cavitation bubbles in Al-18wt.%Cu during ultrasonic melt processing at a fixed acoustic intensity input was exhaustively studied by utilizing synchrotron x-ray photography. The result reveals that the larger bubbles concentrate within an intense cavitation zone close to the radiation face of sonotrode, which is out-surrounded by a weak cavitation zone with bubbles sparse-inhabitation. Most cavitation bubbles obey a truncated size-Gaussian distribution, and the average size decreases as distanced away from the radiation face. The intensive cavitation zone contributes to an effectively refined solidification structure. [ABSTRACT FROM AUTHOR]

Acoustic asymmetric focusing (AAF) can increase the intensity of acoustic energy in a region with one direction, which may greatly benefit medical ultrasound imaging. However, its shortcoming is the narrow bandwidth of the frequency, which severely constrains the application of the AAF lens. In this paper, we propose a broad bandwidth AAF lens based on an asymmetric transmission metamaterial supercell with single-mode output composed of three types of phased unit cells and a wave-guide material. The supercell can realize the asymmetric transmission and the conversion of even-mode to odd-mode simultaneously, due to the phase modulation offered by the phased unit cell and the even-mode band gap of the wave-guide. We design the AAF lens with high performance based on 14 supercells, which demonstrate a long diameter focusing region of 1.56 and short diameter of 0.27 and the broad bandwidth focusing from 3.1 kHz to 4.73 kHz. The proposed AAF lens based on the metamaterial supercells with single-mode output has broad application prospects in the design of asymmetric sound focusing devices with multi-functional capability. [ABSTRACT FROM AUTHOR]

Non-diffracting Bessel acoustic beam that propagates in three dimensions has the properties of self-healing, self-bending, and self-acceleration, giving them many potential applications. Here, we report a zero-order Bessel-like acoustic beam that propagates along a curved trajectory with a phase-modulating acoustic holographic lens. Its pressure distribution on the transverse section approximately conforms to the zero-order Bessel function, and the self-healing property is found. In addition, the maximum point of acoustic intensity on the beam mainlobe can be adjusted by the change in the acoustic frequency. Microbubbles can be forced toward the maximum point along the predefined curve. Therefore, such a beam can be used for the directional transportation of microbubbles with a predefined curve and an adjustable destination. We have numerically calculated the primary Bjerknes force, including the oscillation of the microbubbles with the shell and experimentally proved the curved trajectory and the adjustable destination of the transportation of microbubbles. The proposed method uses the conservative part of the radiation force, which controls the trajectory of microbubbles by the amplitude gradient. The relatively free design of the transport trajectory and destination makes the approach suitable in vivo. [ABSTRACT FROM AUTHOR]

A method is introduced to reconstruct microbarom soundscapes in absolute values. The soundscapes are compared to remote infrasound recordings from infrasound array I23FR (Kerguelen Island) and in situ recordings by the INFRA‐EAR, a biologger deployed near the Crozet Islands. The reconstruction method accounts for all‐acoustic contributions, divided into evanescent microbaroms (detectable directly above the source) and propagating microbaroms (detectable over long ranges). It is computed by integrating acoustic intensities over the ocean surface, convolved with the transfer function quantifying the propagation losses and propagation time. The reconstructed soundscapes are found within 2.7 dB for 85% of the measurements in the microbarom band of 0.1–0.3 Hz. Infrasonic soundscapes are essential for understanding the ambient infrasonic noise field and are a basic need for applications, such as atmospheric remote sensing, natural hazard monitoring, and verification of the Comprehensive Nuclear‐Test‐Ban Treaty. Plain Language Summary: Microbaroms are omnipresent sources of low‐frequency, inaudible sound, that is, infrasound. They have a characteristic and continuous signature within the infrasound spectrum and are often classified as ambient noise. The microbarom signals can be divided into a direct signal, only detectable close by the source, and a propagating signal, which travels over large distances. Under noisy conditions, microbaroms can mask infrasonic signals of interest, such as infrasound from volcanoes or explosions. Insights in the ambient noise field improve natural hazards monitoring and the verification of the Comprehensive Nuclear‐Test‐Ban Treaty. In this study, a method for the reconstruction of the microbarom source field is introduced. The method reconstructs omnidirectional soundscapes in absolute numbers. This is a significant improvement to previous approaches, which accounted for the normalized loudest source region only. The reconstructed soundscapes are compared with microbarom recordings by microbarometer arrays and the INFRA‐EAR, a miniature sensor deployed as a biologger near the Crozet Islands. The comparison shows a statistical agreement for 85% of the time between the modeled and observed soundscapes. Key Points: Evanescent microbaroms and propagating microbaroms are measured on an infrasound bio‐logger fitted to a Wandering AlbatrossA method is developed to reconstruct omnidirectional microbarom soundscapes in absolute values, which can account for both microbarom fieldsThe method is used to quantify the probabilistic microbarom exposure of microbarometers [ABSTRACT FROM AUTHOR]