Sound Direction Research Articles

Influence of sound source directivity on finite element simulation of small-room acoustics

Numerical simulation is a flexible and effective method for room acoustic design. Full-range simulation of room acoustics requires a combination of different numerical methods, in which wave acoustic methods (WAM) and geometric acoustic methods (GAM) are used for the low and high frequency region, respectively. In the general low-frequency WAM simulation, a sound source is often assumed to be a point source or loudspeakers are usually approximated by circular planar pistons. However, compared to a large room, the critical frequency between WAM and GAM should be higher in acoustic simulation of small rooms because of relative size between the wavelength and the room, and thus, the above simplifications of actual sound sources, typically loudspeakers, may lead to errors in terms of directivity in the frequency range that the WAM is applied for. Further errors in the desired room impulse responses or other room acoustic parameters caused by directivity errors needs quantitative analysis, and then evaluation can be made on whether it is necessary to consider a more accurate sound source directivity in the WAM simulation of small room acoustics.

Mismatch negativity linked with sound lateralization in elderly individuals

Elderly individuals tend to experience a decline in auditory functions. One of these is poor lateralization ability. This study aimed to investigate the relationship between sound lateralization and mismatch negativity (MMN) in elderly individuals using a lateralization test and event-related potential (ERP) measuring test. In the lateralization test, participants were presented with sound stimuli with an interaural time difference (ITD) in the right or left ear and were required to indicate the sound direction. The ERP measuring test estimated unconscious brain activity during participants’ exposure to sound stimuli using an ITD in the right or left ear. Two ITDs (i.e., 0.4 ms and 0.8 ms) of a 1-kHz pure tone were measured in elderly and young participants. For sounds with phase reversal between the onset and ongoing parts, young individuals performed lateralization based on the onset part. In contrast, at an ITD of 0.8 ms, elderly participants unable to perceive the onset part tended to demonstrate less negative MMN. In conditions where the preceding ear in onset and ongoing parts was reversed, elderly participants exhibited ambiguous lateralization, and their cortical evoked potentials did not significantly differ from activity associated with standard stimuli without an ITD.

Sound intensity and directivity measurements for a loudspeaker canopy in a restrictive noise environment

It is common to have noise complaints from outdoor event and entertainment venues in urban and non-urban environments due to the loudness of the reinforcement system, rhythmic nature of the music, acoustical spectrum, and the geometric spreading of said system. Complaints about noise from events, bars, and restaurants are on the rise. Increasing traffic, construction, and commercial activities tend to increase the ambient noise level in urban environments, creating noise creep. The pandemic restrictions helped reduce the ambient levels in the urban and non-urban areas. However, after the reopening, more and more noise complaints started to be issued since residents were more sensitive to noise pollution. This paper presents a practical application of the source directivity for a loudspeaker system. The loudspeaker canopy is designed to produce a radiation pattern directing the main beam lobe to the front of the array and reduce the noise propagation to other directions. This device can be implemented in entertainment and outdoor events (such as wedding parties) to reduce the noise impact on sensitive receivers and meet the jurisdictional noise regulations. Real-world acoustic intensity measurements were made to obtain the system's sound power and assess the noise impact at distances up to 35 feet away from the source. The viability of using the system for outdoor activities within locations restricted by the City's ordinances is discussed.

Ambient sound directionality and rapid estimation of empirical Green’s functions in a coastal ocean

Noise interferometry offers an opportunity for passive ocean remote sensing through retrieval of empirical Green’s functions (EGFs) from cross-correlations of ambient sound. At ranges of tens of ocean depths, obtaining stable and accurate EGF estimates usually requires noise averaging periods of hours or days. Decreasing the necessary averaging times without compromising the EGF accuracy is critically important for operational applications. Using data acquired in the Shallow Water 2006 experiment on the continental shelf off New Jersey, it has been found that occasionally averaging periods as short as a few minutes are sufficient. The phenomenon is observed for various receiver pairs but does not occur simultaneously in all azimuthal directions. Short averaging periods give EGFs in a broader frequency band and with a richer mode content. These are better suited to monitor physical processes in the water column. The conditions conducive to rapid EGF emergence are studied using in situ temperature measurements, meteorological information, and the acoustic data acquired with a horizontal line array. Strong intermittency is observed in the horizontal directionality of ambient sound. For various receiver pairs, EGFs are found to emerge rapidly when ambient sound directionality favors propagation in the direction from one receiver to the other.

A Design Method for Vibration and Acoustic Reduction of the Power System in an Underwater Automobile Glider

Underwater automobile gliders (AUGs) are new underwater vehicles, that should have lightweight structures with low vibration and acoustic characteristics due to their working conditions. This paper proposes a design method for vibration and acoustic reduction of the power system in an AUG by using the stand-off layer perforated viscoelastic material (SOL-PVEM) damping treatment with lightweight characteristics. The finite element method is used to calculate the vibration characteristics and modal loss factors of the plates with different SOL-PVEM damping treatments. The influence of the perforation of the damping layer on the modal loss factor is investigated. Then, the structure and acoustic coupling of finite element models of the power system with the SOL-VEM and SOL-PVEM damping treatments are established. The vibration acceleration, sound power, and sound pressure directivity of the power system of the AUG coated with the two proposed damping treatments are analyzed respectively. The results show that the vibration and acoustic responses of the power system can be effectively reduced by using the proposed lightweight SOL-PVEM damping treatment.

Effect of double-constrained potential on the ground-state binding energy of magnetopolaron in a quantum well

This study aims at investigating the properties of magnetopolarons (MPs) in III–V compound semiconductors: GaP, GaAs and GaSb crystals. The obtained results from numerical calculation revealed that absolute value of ground-state (GS) binding energy [Formula: see text] of the magnetopolaron is affected by magnetic field, type of crystal as well as the parabolic and asymmetric Gaussian potentials, which leads to a series of interesting phenomena. The study of results obtained provides a good theoretical guidance on optoelectronic devices and quantum information. We have theoretically investigated the origins of these strange phenomena, and our findings provide sound theoretical direction for photoelectric technology and quantum information.

Influence of Magnetic Field on Sound Transmission Loss of the Unit Filled with Magnetorheological Fluid.

To explore the feasibility of applying magnetorheological fluids (MRFs) in the field of noise control, the influence of the magnetic field intensity and direction on the sound transmission loss (STL) of a unit filled with MRF (MRF unit) were investigated in this study. First, two types of test sample containing the MRF unit were designed and fabricated. The magnetic field applied to the MRF was provided by the permanent magnets used in pairs. The direction of the magnetic field was perpendicular or parallel to the direction of the sound wave propagation. The distribution of the magnetic field intensity of the two types of test samples was simulated using magnetostatic finite element analysis and validated with the magnetic field intensity measured using a Teslameter. For comparison, test samples containing air and water units were also prepared. Then, the STL of the two types of test samples were measured under different magnetic field intensities using the impedance tube method. Finally, the STL curves of the two types of test samples were presented, and the influence of magnetic field intensity and direction on the STL were discussed. The results demonstrate that the magnetic field direction has a significant influence on the STL of the MRF unit. In addition, when the magnetic field direction is parallel to the sound propagation direction, the STL of the test sample containing MRF unit significantly increases with the increase of the magnetic field intensity at low and middle frequencies.

Erratum: Pseudogauge field driven acoustoelectric current in two-dimensional hexagonal Dirac materials [Phys. Rev. B 105 , 125407 (2022)

Using a diagrammatic scheme, we study the acoustoelectric effects in two-dimensional (2D) hexagonal Dirac materials due to the sound-induced pseudo-gauge field. We analyze both uniform and {\em spatially dispersive} currents in response to copropagating and counterpropagating sound waves, respectively. In addition to the longitudinal acoustoelectric current, we obtain an exotic {\em transverse} charge current flowing perpendicular to the sound propagation direction owing to the interplay of transverse and longitudinal gauge field components $j_T\propto A_L A^\ast_T$. In contrast to the almost isotropic directional profile of the longitudinal uniform current, a highly anisotropic transverse component $j_T\sim\sin(6\theta)$ is achieved that stems from the inherited three-fold symmetry of the hexagonal lattice. However, both longitudinal and transverse parts of the dispersive current are predicted to be strongly anisotropic $\sim\sin^2(3\theta)$ or $\cos^2(3\theta)$. We quantitatively estimate the pseudogauge field contribution to the acoustoelectric current that can be probed in future experiments in graphene and other 2D hexagonal Dirac materials.

Virtual Antenna Array With Directional Antennas for Millimeter-Wave Channel Characterization

Millimeter-wave (mm-Wave) band channel modeling and characterization are essential for system design and analysis in the fifth generation (5G) and future communication systems. Reliable channel sounding in the deployment scenarios is required for accurate and realistic channel modeling and characterization. In the state of the art, directional scanning sounding (DSS) and virtual antenna array (VAA) sounding are two popular methods due to their simplicity and cost-effectiveness. The DSS and the VAA methods are typically based on mechanically rotatable directional antennas and mechanically movable omnidirectional antennas, respectively. However, the spatial resolution is limited by the directivity and high sidelobes of the directional antennas used in the DSS method. The conventional VAA method also has limitations in terms of the low signal-to-noise ratio (SNR) and the unavailability of suitable omnidirectional antennas that support mmWave (above 60 GHz) band measurements and wideband horizontal polarization measurements. In this article, a novel directional antenna-based VAA framework in combination with the associated beamforming algorithm is proposed. Compared to the state-of-the-art methods, the proposed framework can achieve high angular resolution and high SNR for mm-Wave channel measurements without introducing additional cost and measurement time. Furthermore, it is a generic solution that can be applicable for arbitrary frequency bands and polarizations, unlike the conventional VAA method. To validate the effectiveness and robustness of the proposed method, experiments in two scenarios (a clean anechoic chamber and a realistic indoor meeting room) were conducted over 28–30 GHz with two types of directional antennas (i.e., a horn antenna and a corrugated antenna). Besides, the advantages of the proposed method are highlighted with a comparison to the conventional VAA and DSS methods.

Research on ultrasonic sparse DC-TFM imaging method of rail defects

Rail damage is usually the main factor that affects the safe operation of trains, which may even lead to catastrophic accidents, such as train derailment and capsizing. It’s important to accurately detect the internal damage of the rail in real time. Ultrasonic testing is a main technology for the detection of rail damage in China, but there are some problems of misdetection and omission due to irregular rail shape, poor coupling, difficulty in automatic alignment, and inconvenient adjustment of the incident angle of the ultrasonic wafer, which results in a damage review rate of rail-defect detection lower than 78% in China. In this study, the phased array total focus method (TFM) imaging was applied to rail-damage detection, and the directivity correction-based sparse TFM imaging method (DC-TFM) was proposed to solve the problems of the existing phased array TFM imaging methods, such as inaccuracy and long computing time. The directivity function of array elements was used to correct the sound field intensity of different pixels to improve the accuracy of the TFM imaging. The experimental results show that the accuracy of the TFM imaging of defects is improved by 28% with correction of the sound field directivity. A sparse array designed based on the particle swarm optimization (PSO) algorithm was used to replace the full matrix data for the DC-TFM imaging, ensuring the imaging quality and reducing the imaging computing time. When the sparse rate is 75%, the array performance indicator (API) and the signal-to-noise ratio (SNR) are reduced only slightly, but the imaging computing time is shortened substantially by more than 40%, which indicates that the proposed sparse DC-TFM method can effectively improve the speed of rail-damage detection.

Aeroacoustic installation effects in multi-rotorcraft: Numerical investigations of a small-size drone model

The noise associated with the growing presence of unmanned aerial vehicles such as professional drones is becoming a concern. The buzzing noise emitted by multicopter drones is particularly distracting and annoying. The root mechanisms causing this tonal noise in multicopter configurations are however poorly understood and constitute the focus of this study. We developed a hybrid methodology that couples unsteady Reynolds-Averaged Navier-Stokes simulations with a computational aeroacoustic approach based on the Finite Element Method. This has permitted quantifying propeller-propeller and propeller-airframe aerodynamic installation effects, and the airframe scattering effects. The methodology is validated by comparing the predicted tones with existing acoustic measurements in the literature. The aerodynamic simulations indicate that the dominant sound sources are due to the unsteady interactions of the blade with the other propellers and supporting struts. This necessitates simulating the entire system in order to obtain realistic fluctuations of the aerodynamic forces. Similarly, the sound directivity results indicate that the acoustic scattering by the airframe has also a significant effect, both in the geometrical near- and far-field of the drone.

The acoustic streaming effects of sonic black hole

In this paper, the acoustic streaming effects of Sonic Black Hole (SBH) are deeply studied by using the numerical and simulation method. By solving Navier–Stokes equations of compressible fluid, we analyze the flow characteristics of acoustic medium in SBH excited by sound wave, and further discuss the acoustic streaming effects and sound wave capture mechanism of SBH. The phenomenon of simultaneous reduction of medium and high-frequency sound reflection and transmission is analyzed. Under the excitation of medium- and high-frequency sound waves, the interaction between fluid medium flow and SBH structure leads to the uneven internal velocity distribution in the sound propagation direction, which can lead to the phenomenon of sound wave capture and deceleration. For low-frequency sound waves, the velocity distribution of sound medium is uniform, and there is almost no change in velocity gradient, resulting in the uniform distribution of sound pressure without sound absorption. These theoretical and numerical results are in good agreement with the experimental results in the literature, and also verify our results. Finally, by improving the structure, increasing the complexity of sound medium flow and the gradient change in the direction of sound propagation, the sound absorption and insulation ability of the SBH can be further improved. This study reveals the sound transmission mechanism of SBH, which can provide a new idea for the suppression of low-frequency sound waves in SBH.

Acoustical impacts on hard disk drive dynamics

Acoustical output from air movers in computing systems can reach sufficiently high sound pressure levels and in frequency bands such that performance of Hard Disk Drives (HDD) is degraded. In this paper air mover acoustical characteristics and comparisons to standalone measurements and models relevant to the performance issues are explored. Sound pressure levels, frequency bands, directivity, and explicit source descriptions are considered for air mover sources, and duct transmission, statistical energy, acoustic diffusion, and measured transfer factors are considered for noise transmission along acoustic path(s) from air mover to HDD within computing systems.

Large-scale anechoic characterization of small caliber firearm impulse noise

Three-dimensional source characterization is crucial for determining noise metrics produced by operating a firearm in indoor environments. Anechoic measurements for sound power and directivity measurement are challenging for small caliber firearms. In order to create high fidelity source models of an M4A1 firearm (firing blanks), a team from Ball Aerospace, Inc., the Air Force Research Laboratory, and Brigham Young University conducted an expansive characterization within an anechoic facility located at the Owens Corning Acoustic Research Complex using a two-meter spherical microphone array centered on the muzzle of the weapon. The array consisted of a quarter sphere of over forty microphones at various elevation and azimuth angles. By rotating the weapon, an entire closed sphere of over one hundred points were sampled with multiple shots. Differences in directivity, sound power level and shot to shot repeatability are examined for two weapon configurations. These differences reinforce the idea that accurate source characterizations are required for modelling small caliber firearm noise propagation. The views expressed are those of the author and do not necessarily reflect the official policy or position of the Department of the Air Force, the Department of Defense, or the U.S. government.

Human-mimetic binaural ear design and sound source direction estimation for task realization of musculoskeletal humanoids

Human-like environment recognition by musculoskeletal humanoids is important for task realization in real complex environments and for use as dummies for test subjects. Humans integrate various sensory information to perceive their surroundings, and hearing is particularly useful for recognizing objects out of view or out of touch. In this research, we aim to realize human-like auditory environmental recognition and task realization for musculoskeletal humanoids by equipping them with a human-like auditory processing system. Humans realize sound-based environmental recognition by estimating directions of the sound sources and detecting environmental sounds based on changes in the time and frequency domain of incoming sounds and the integration of auditory information in the central nervous system. We propose a human mimetic auditory information processing system, which consists of three components: the human mimetic binaural ear unit, which mimics human ear structure and characteristics, the sound source direction estimation system, and the environmental sound detection system, which mimics processing in the central nervous system. We apply it to Musashi, a human mimetic musculoskeletal humanoid, and have it perform tasks that require sound information outside of view in real noisy environments to confirm the usefulness of the proposed methods.

Application of resistivity sounding in Quaternary stratigraphic division in Yixing, Eastern China

Abstract Stratigraphic classification and correlation are fundamental for the study of regional geology, tectonic structures and paleogeographic evolution. Geological structures have undergone a dramatic change since the Quaternary. However, the division of the Quaternary stratigraphic boundary in southeastern China is debated. In this study, we used a direct current vertical electric sounding method to study the Quaternary strata in Yixing, Jiangsu, China. Using one-dimensional resistivity inversion and analyzing the regional geology and geological core data, the electrical features of the study area were evaluated. We found good agreement between the geological core data and lithological data, and we were able to identify two stratigraphic groups: the hilly sedimentary area in the southwest and the Tai Lake plain sedimentary area in the northeast. The latter can further subdivided into two parts. Division and classification of the Quaternary strata in the study area provide a basis for locating areas likely to have a high pore-confined water content (such as Gaoteng, Heqiao and Wanshi town), whereby useful information is provided for groundwater exploitation for emergency use.

Network Pharmacology and Bioinformatics Approach Reveals the Multi-Target Pharmacological Mechanism of Fumaria indica in the Treatment of Liver Cancer.

Liver cancer (LC), a frequently occurring cancer, has become the fourth leading cause of cancer mortality. The small number of reported data and diverse spectra of pathophysiological mechanisms of liver cancer make it a challenging task and a serious economic burden in health care management. Fumaria indica is a herbaceous annual plant used in various regions of Asia to treat a variety of ailments, including liver cancer. Several in vitro investigations have revealed the effectiveness of F. indica in the treatment of liver cancer; however, the exact molecular mechanism is still unrevealed. In this study, the network pharmacology technique was utilized to characterize the mechanism of F. indica on liver cancer. Furthermore, we analyzed the active ingredient-target-pathway network and uncovered that Fumaridine, Lastourvilline, N-feruloyl tyramine, and Cryptopine conclusively contributed to the development of liver cancer by affecting the MTOR, MAPK3, PIK3R1, and EGFR gene. Afterward, molecular docking was used to verify the effective activity of the active ingredients against the prospective targets. The results of molecular docking predicted that several key targets of liver cancer (along with MTOR, EGFR, MAPK3, and PIK3R1) bind stably with the corresponding active ingredient of F. indica. We concluded through network pharmacology methods that multiple biological processes and signaling pathways involved in F. indica exerted a preventing effect in the treatment of liver cancer. The molecular docking results also provide us with sound direction for further experiments. In the framework of this study, network pharmacology integrated with docking analysis revealed that F. indica exerted a promising preventive effect on liver cancer by acting on liver cancer-associated signaling pathways. This enables us to understand the biological mechanism of the anti liver cancer activity of F. indica.

Использование понятия геофизической модельной функции при интерпретации данных скаттерометра

Within the framework of a two-scale Bragg (resonant) scattering model, the relationship between the spatial characteristics of sea surface waves and the geophysical model function (GMF) is analyzed. The dependence of the GMF on the angle between the direction of sounding and the wind velocity vector is determined by the function of the angular distribution of Bragg waves and the angular distribution of longer waves. In strong winds, the wave breaking makes a noticeable contribution to the radar signal. With calm and moderate winds, the main characteristics of the GMF can be interpreted within the framework of a two-scale Bragg scattering model. The exception is the appearance of negative values of the longitudinal-transverse asymmetry of GMF, which is observed in the L band of radio waves. Negative longitudinal-transverse asymmetry corresponds to lower values of the normalized cross-section of backscattering when probing along the wind direction than in the transverse direction.

Effects of periodic suction-blowing excitation on the aerodynamic sound generated by a laminar flow past a square cylinder using the direct numerical simulation approach

This paper analyzes the effects of a periodic suction-blowing excitation on the aerodynamic sound generated by a laminar flow past a square cylinder using the direct numerical simulation approach. The periodic suction-blowing excitation has been prescribed on the top and bottom surfaces of the square cylinder. The proper orthogonal mode decomposition (POD) technique has been used to find information about important modes associated with disturbance pressure fields. The POD technique separated the contribution of the dominant lift dipole equivalent sources and the drag dipole equivalent sources to the disturbance pressure field for the no-excitation case. The POD technique also revealed that the periodic suction-blowing excitation introduced an additional monopole equivalent sound source and a drag dipole equivalent sound source due to periodic enhancement and reduction of the body’s effective cross-sectional area. Modifications in the sound field due to changes in excitation amplitude, forcing frequency, and the phase delay between the excitation and vortex shedding process have been studied in detail. Although no significant changes in the flow field were noticed due to a small amplitude of excitation, the directivity of the sound field was significantly altered. The sound fields have been classified into five distinct zones for different periodic suction-blowing excitation frequencies. The beats of sounds were noted when the forcing frequency of excitation and the Strouhal frequency associated with vortex shedding were sufficiently close. It is observed that the in-phase excitation in which either blowing or suction is applied on both surfaces of a cylinder at a particular instant introduces a significant bias in the sound field directivity. The interaction between the lift dipole equivalent sources due to vortex shedding and the monopole and the drag dipole equivalent sources due to excitation introduces a bias in the sound field directivity. As a result, a dominant sound field is observed either in the top-left or in the bottom-left parts of the domain.

Effect of listener head orientation on speech reception threshold in an automotive environment

The head orientation of the listener significantly affects speech intelligibility (SI) in automobiles due to the effect of binaural listening and special acoustic conditions such as early reflections and seat-back occlusions. However, this issue has not been studied with subjective tests yet. This study investigates SI with various head orientations of a listener in automobiles with an subjective experiment. The sentence speech reception thresholds (SRT) in Mandarin Chinese are measured via headphones virtually in an automobile environment, and compared with results in a weak-reflective listening room. A virtual speaker is located in the front-passenger seat, the right-back seat and the left-back seat in sequence, by convolving the target speech with corresponding binaural room impulse responses measured on a dummy head in the driver’s seat with five head orientations. Result shows that the SRT variations caused by head orientations are up to 5 dB in automobile, lower than that of 9 dB in listening room. Under various head orientations, the SRT in automobile decreases as the virtual speaker moves closer to the front lateral direction, which is similar to the change rule in listening room that is mainly determined by the effect of binaural listening. Overall, a lower SRT in automobile can be obtained when the listener in the driver seat turns their head inward, i.e., towards the right. In comparison with the result in listening room, early reflections improve SI in automobile by an SRT decrease of up to 3.5 dB, while seat-back occlusions reduce SI by an SRT increase of up to 5.3 dB. The early reflections play a more significant role when the listener is in an adverse position, e.g., for the head orientations and speaker locations making direct sounds difficult to reach the listener’s ears. Comparison between the SRTs based on speech transmission index (STI) and STI-SI models and the SRTs measured by subjective experiment indicates that the STI-based objective method only partially expresses the variation in SI obtained from subjective experiment, and the difference between the subjective results and the objective results is mainly caused by the inapplicability of the STI-SI models derived from the traditional room in the automotive environment. The present work is relevant to understanding the combined effect of various factors on SI under such a special acoustic condition in automobile.