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Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department 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.)

The holographic signal-processing method for a single vector scalar receiver (VSR) in the high-frequency band in shallow water is developed in the paper. The aim of this paper is to present the results of the theoretical analysis, numerical modeling, and experimental verification of holographic signal processing for a noise source by the VSR. The developed method is based on the formation of the 2D interferogram and 2D hologram of a noise source in a shallow-water waveguide. The 2D interferograms and 2D holograms for different channels of the VSR (P sound pressure and V X and V Y vibration velocity components) are considered. It is shown that the 2D interferogram consists of parallel interference fingers in the presence of a moving noise source. As a result, the 2D hologram contains focal points located on a straight line, and the angular distribution of the holograms has the main extreme value. It is shown in the paper that the holographic signal-processing method allows detecting the source, estimating the source bearing, and filtering the useful signal from the noise. The results of the source detection, source bearing estimation, and noise filtering are presented within the framework of experimental data processing and numerical modeling. [ABSTRACT FROM AUTHOR]

This article presents a study conducted to evaluate the acoustic quality of the Goseck Circle, an ancient circular enclosure, also known as a rondel, situated in Saxony, Germany. Goseck Circle is an example of monumental buildings from the Neolithic period, which are called rondels. The facility was discovered in the 1990s. Then the facility was archaeologically reconstructed and opened to the public in 2005. Currently, it is considered to be the oldest known structure of this type, and its creation is estimated at around 4900 BC. Goseck Circle is roughly of a circular shape. It has one ditch and two palisade rings. There are three entrances leading to the interior of this facility. Therefore, the Goseck Circle is considered as the oldest solar observatory, as a worship, or a ritual place. A number of studies on both contemporary and archaeological facilities indicate that the facilities display the characteristic features depending on their intended use. Therefore, it can be assumed that if the Goseck Circle was to be a place of worship, then in terms of the acoustic aspects, it should be characterized by such values of the acoustic parameters, that will also prove this. This concept was the reason for carrying out a series of numerical calculations that allowed for the determining of the selected parameters characterizing the acoustic field inside the analysed facility. [ABSTRACT FROM AUTHOR]

Moving microphones allow for the fast acquisition of sound-field data that encode acoustic impulse responses in time-invariant environments. Corresponding decoding algorithms use the knowledge of instantaneous microphone positions for relating the dynamic samples to a positional context and solving the involved spatio-temporal channel estimation problem subject to the particular parameterization model. Usually, the resulting parameter estimates are supposed to remain widely unaffected by the Doppler effect despite the continuously moving sensor. However, this assumption raises issues from the physical point of view. So far, mathematical investigations into the actual meaning of the Doppler effect for such dynamic sampling procedures have been barely provided. Therefore, in this paper, we propose a new generic concept for the dynamic sampling model, introducing a channel representation that is explicitly based on the instantaneous Doppler shift according to the microphone trajectory. Within this model, it can be clearly seen that exact trajectory tracking implies exact Doppler-shift rendering and, thus, enables unbiased parameter recovery. Further, we investigate the impact of non-perfect trajectory data and the resulting Doppler-shift mismatches. Also, we derive a general analysis scheme that decomposes the microphone signal along with the encoded parameters into particular subbands of Doppler-shifted frequency components. Finally, for periodic excitation, we exactly characterize the Doppler-shift influences in the sampled signal by convolution operations in the frequency domain with trajectory-dependent filters. [ABSTRACT FROM AUTHOR]

In order to study the effect of splitter blades on the internal and external sound field of the hydraulic turbine, the paper chose a centrifugal pump with a specific speed n s= 33 reversed as a hydraulic turbine as the research object, and added the short blades on the original impeller to form a new splitter impeller. Based on the Re-Normalization Group (RNG) k-ε turbulence model to conduct numerical simulation for the hydraulic turbine, this thesis calculated the internal and external acoustic field by means of the acoustic boundary element (BEM) and finite element (FEM) and analyzed the noise radiation characteristics of the two models under different working conditions. The results show that the blade frequency is the main factor affecting the inlet and outlet sound pressure, and the optimized model decreases the inlet and outlet sound pressure levels by 6.84 and 7.24 dB in optimal working conditions. Rotor-stator interaction is the main reason for the flow-induced noise of hydraulic turbine volute appearing, the optimized model can effectively reduce the impeller and volute rotor-stator interaction and the flow-induced noise of volute. Outfield maximum sound pressure appears at the inlet and the volute tongue, which decreased by 1.84, 6.07, and 5.24 dB at each operating condition. To sum up, splitter blades can improve hydraulic characteristics and flow field noise in the hydraulic turbine. [ABSTRACT FROM AUTHOR]

Moving microphones allow for the fast acquisition of sound-field data that encode acoustic impulse responses in time-invariant environments. Corresponding decoding algorithms use the knowledge of instantaneous microphone positions for relating the dynamic samples to a positional context and solving the involved spatio-temporal channel estimation problem subject to the particular parameterization model. Usually, the resulting parameter estimates are supposed to remain widely unaffected by the Doppler effect despite the continuously moving sensor. However, this assumption raises issues from the physical point of view. So far, mathematical investigations into the actual meaning of the Doppler effect for such dynamic sampling procedures have been barely provided. Therefore, in this paper, we propose a new generic concept for the dynamic sampling model, introducing a channel representation that is explicitly based on the instantaneous Doppler shift according to the microphone trajectory. Within this model, it can be clearly seen that exact trajectory tracking implies exact Doppler-shift rendering and, thus, enables unbiased parameter recovery. Further, we investigate the impact of non-perfect trajectory data and the resulting Doppler-shift mismatches. Also, we derive a general analysis scheme that decomposes the microphone signal along with the encoded parameters into particular subbands of Doppler-shifted frequency components. Finally, for periodic excitation, we exactly characterize the Doppler-shift influences in the sampled signal by convolution operations in the frequency domain with trajectory-dependent filters.

Background: With the advent of cochlear implants, tactile aids for the profoundly deaf became obsolete decades ago. Nevertheless, they might still be useful in rare cases. We report the case of a 25-year-old woman with Bosley–Salih–Alorainy Syndrome and bilateral cochlear aplasia. Methods: After it was determined that cochlear or brainstem implants were not an option and tactile aids were not available anymore, a bone conduction device (BCD) on a softband was tried as a tactile aid. The usual retroauricular position and a second position close to the wrist, preferred by the patient, were compared. Sound detection thresholds were measured with and without the aid. Additionally, three bilaterally deaf adult cochlear implant users were tested under the same conditions. Results: At 250–1000 Hz, sounds were perceived as vibrations above approximately 45–60 dB with the device at the wrist. Thresholds were approximately 10 dB poorer when placed retroauricularly. Differentiation between different sounds seemed difficult. Nevertheless, the patient uses the device and can perceive loud sounds. Conclusions: Cases where the use of tactile aids may make sense are probably very rare. The use of BCD, placed, e.g., at the wrist, may be useful, but sound perception is limited to low frequencies and relatively loud levels.

A system of initially immobile spherical liquid drops placed in another liquid in the field of a propagating acoustic wave is considered. The acoustic radiation force acting on each spherical liquid drop is determined as the function of the incident wave frequency, making use of the solution of a problem of plane harmonic wave scattering on a system of two spherical bodies. The problem is solved by the variable separation method. To satisfy the boundary conditions on spherical surfaces, the expansion of the incident and reflected wave potentials over the spherical wave functions are used. Required constants in the solution are calculated from an infinite system of the algebraic equations, which is solved by a truncation method. It is established that the value of the acoustic radiation force affecting each liquid drop depends significantly on the densities, speed of sound in the outer and internal liquid, as well as on the distance between drops. It is also found that the acoustic radiation force has the same or opposite direction as the incident sound wave depending on its frequency. As result, at different frequencies, the liquid drops can start moving towards or further away from each other. [ABSTRACT FROM AUTHOR]

This study considers the practical issue of severe noise observed in a multi-stage sleeve control valve within an engineering project. Employing computational fluid dynamics (CFD) methodology, we initially performed numerical simulations to analyze the steady-state flow field within the control valve. Subsequently, we identified the underlying factors contributing to the noise issue within the valve. To assess the aerodynamic noise of the control valve, we applied the FW-H acoustic analogy theory and determined the intensity and distribution characteristics of the aerodynamic noise. Finally, we validated the numerical simulation results of the aerodynamic noise against theoretical calculations. Our findings indicate that the steam medium experiences high-speed flow due to disturbances caused by various components within the valve, resulting in significant turbulence intensity. This intense turbulence leads to pressure fluctuations in the steam, serving as the main catalyst for noise generation. The aerodynamic noise of the control valve exhibits a roughly symmetrical distribution along the pipe–valve system, with noticeable increases in noise levels upstream and downstream of the valve compared to other regions. The distribution cloud map obtained from the numerical simulations serves as a valuable reference for analyzing the locations where aerodynamic noise is generated. Comparing the numerical simulation results with the theoretical calculations at the noise monitoring points, we found that the noise error of the monitoring points was less than 5%, which proves the effectiveness of the numerical simulation method. These results provide essential data support for the acoustic detection of aerodynamic noise in control valves, carrying significant practical implications for engineering applications. [ABSTRACT FROM AUTHOR]

The holographic signal-processing method for a single vector scalar receiver (VSR) in the high-frequency band in shallow water is developed in the paper. The aim of this paper is to present the results of the theoretical analysis, numerical modeling, and experimental verification of holographic signal processing for a noise source by the VSR. The developed method is based on the formation of the 2D interferogram and 2D hologram of a noise source in a shallow-water waveguide. The 2D interferograms and 2D holograms for different channels of the VSR (P sound pressure and VX and VY vibration velocity components) are considered. It is shown that the 2D interferogram consists of parallel interference fingers in the presence of a moving noise source. As a result, the 2D hologram contains focal points located on a straight line, and the angular distribution of the holograms has the main extreme value. It is shown in the paper that the holographic signal-processing method allows detecting the source, estimating the source bearing, and filtering the useful signal from the noise. The results of the source detection, source bearing estimation, and noise filtering are presented within the framework of experimental data processing and numerical modeling.

Copyright of Materiały Budowlane is the property of Wydawnictwo SIGMA-NOT 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.)

In response to the drawbacks of low efficiency, cumbersome calculation, and easy-to-fall local optimal solutions in existing shallow water acoustic parameters inversion research, this paper proposes a shallow water acoustic parameters inversion method based on a feedback (BP) neural network model. Firstly, the theoretically predicted values of the shallow water sound pressure field are obtained through the fast field method (FFM). Secondly, a relationship model between the predicted sound pressure field and the inversion of ground sound parameter values is established based on the BP neural network model. Finally, the measured sound pressure field data are brought into the neural network model to obtain the inversion results. The application results of the method indicate that, compared to the classical simulated annealing (SA) algorithm, the BP neural network model converts the data-matching process of the optimization algorithm into the construction of a relationship model between the input data and the desired parameters, avoiding repeated matching and optimization processes. Therefore, it can directly, accurately, and efficiently output the inversion results. Under the premise of setting the same accuracy, the iteration number of the BP neural network model is reduced to 2% of the SA algorithm, cutting the calculation time to 30% of the SA algorithm. It has broad application prospects in shallow sea acoustic parameters inversion algorithms. [ABSTRACT FROM AUTHOR]

Background: With the advent of cochlear implants, tactile aids for the profoundly deaf became obsolete decades ago. Nevertheless, they might still be useful in rare cases. We report the case of a 25-year-old woman with Bosley–Salih–Alorainy Syndrome and bilateral cochlear aplasia. Methods: After it was determined that cochlear or brainstem implants were not an option and tactile aids were not available anymore, a bone conduction device (BCD) on a softband was tried as a tactile aid. The usual retroauricular position and a second position close to the wrist, preferred by the patient, were compared. Sound detection thresholds were measured with and without the aid. Additionally, three bilaterally deaf adult cochlear implant users were tested under the same conditions. Results: At 250–1000 Hz, sounds were perceived as vibrations above approximately 45–60 dB with the device at the wrist. Thresholds were approximately 10 dB poorer when placed retroauricularly. Differentiation between different sounds seemed difficult. Nevertheless, the patient uses the device and can perceive loud sounds. Conclusions: Cases where the use of tactile aids may make sense are probably very rare. The use of BCD, placed, e.g., at the wrist, may be useful, but sound perception is limited to low frequencies and relatively loud levels. [ABSTRACT FROM AUTHOR]

The possibility of controlling localized fields in multimode shallow water waveguides based on the principle of interference invariance was studied. Within the framework of the numerical experiments in a wide frequency range of 100–350 Hz and range intervals of 10–100 km, the possibilities of focusing the sound field by wavefront reversal and controlling of the focusing of the focal spot by frequency tuning in shallow water waveguides was analyzed. The focal spot scanning was carried out by frequency tuning with a fixed distribution of the sound field at receiving and transmitting vertical antenna apertures. A comparative analysis of the features of focusing and focal spot control for summer and winter stratification of the water layer was carried out. It is shown that the parameters of the focal spot during frequency tuning were more stable in the winter waveguide. It is demonstrated that the sound frequency tuning had a piecewise continuous character and was carried out on a domain of one continuous track and jump-passing on the other track in accordance with the waveguide interference fringes in the range–frequency domain. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic 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 Large Electric Machine & Hydraulic Turbine is the property of Large Electric Machine & Hydraulic Turbine Editorial Office 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.)

The sound field model of an irregular enclosure with two elastic walls and an inclined wall is established by the modal theory. The modal parameters of the irregular enclosure are obtained by the envelope rectangular technique. The influence of the inclination wall angle on the sound field in the irregular enclosure is discussed. When the inclination angle is increased from 0° to 45°, the resonance frequencies of the acoustic enclosure are basically reduced in the frequency range of 0∼250 Hz. When the inclination angle is increased from 0° to 45° every 15° interval, the amplitude of a certain acoustic mode itself decreases, while the amplitudes of the acoustic modes coupled to it basically increase. The acoustic potential energy peaks in the enclosure basically shift to the low frequency with the increase of the inclination angle. Furthermore, the change trend of the acoustic potential energy is regular in the low-order modes, but relatively chaotic in the high-order modes. In addition, in order to verify that the accurate description of the primary sound field is the basis of effective noise control, the two-elastic plate model is deliberately treated as one-elastic plate model, and its influence on the performance of active noise control is discussed. Also, if the multi-elastic plate model is regarded as a simplified automobile cab, the research results can be used for the preliminary acoustic design of the cab; that is, the research results can be used for the acoustic design of similar models. [ABSTRACT FROM AUTHOR]

A system of initially immobile spherical liquid drops placed in another liquid in the field of a propagating acoustic wave is considered. The acoustic radiation force acting on each spherical liquid drop is determined as the function of the incident wave frequency, making use of the solution of a problem of plane harmonic wave scattering on a system of two spherical bodies. The problem is solved by the variable separation method. To satisfy the boundary conditions on spherical surfaces, the expansion of the incident and reflected wave potentials over the spherical wave functions are used. Required constants in the solution are calculated from an infinite system of the algebraic equations, which is solved by a truncation method. It is established that the value of the acoustic radiation force affecting each liquid drop depends significantly on the densities, speed of sound in the outer and internal liquid, as well as on the distance between drops. It is also found that the acoustic radiation force has the same or opposite direction as the incident sound wave depending on its frequency. As result, at different frequencies, the liquid drops can start moving towards or further away from each other.

A new definition of the hydroacoustic field invariant based on a stable estimate of the invariance of orthogonal projections of the sound-pressure-phase gradients on the "distance–frequency" plane is introduced. Such a definition generalizes the concept of an invariant to all existing zones of shallow and deep seas including the near and far zones of illumination of the deep sea in which it is impossible to estimate and apply the Chuprov interference invariant. In the zone of existence of the Chuprov invariant, its values almost coincide with the values of the new invariant. [ABSTRACT FROM AUTHOR]

The relatively low piezoelectric constant of aluminum nitride (AlN) piezoelectric film limits the development and application of the acoustic field performance of AlN-based micromachined ultrasonic transducers; thus, in this study we establish a mid- to low-frequency transducer unit model to address this problem. The transducer operates at 4.5 MHz, and the construction of a clamped structure is first investigated to ensure the feasibility of performance analysis. Secondly, the effectiveness of the optimized upper electrode distribution proposed in this paper in improving the acoustic field radiation of the array element is also compared with the original structure. Finally, the influence of the optimized electrode geometry parameters on the acoustic wave direction is analyzed. The finite element simulations are performed in the COMSOL Multiphysics (COMSOL) software and post-processing results are analyzed. Based on the simulation results, the proposed optimal distribution of the upper electrode makes the radiation beam uniform and symmetrical in the case of both the clamped model and the optimized structure model. In the case of the upper electrode radius of 28 µm, this electrode division operation makes the unit vibration mode switching in the frequency range more moderate. The sound field radiation improvement of the proposed optimized structure model is better than that of the clamped structure. [ABSTRACT FROM AUTHOR]

Radial shock wave therapy is used for different therapeutic indications. In order to assess the effect on the treated tissue, it is important to know the sound field parameters. However, it is challenging to measure the pressure curves of ballistic devices, especially at high pulse repetition rates. In the new standard IEC 63045:2020 two possibilities for sound field measurements of non-focusing devices are described, a wet and a dry test bench. The whole sound field can be characterised using a wet test bench, but the process is cumbersome and cavitation is likely to occur at high pulse repetition rates. This effect is avoided using a dry test bench where the measurement position is limited to a single spot. Therefore, a hybrid test bench was developed combining the dry bench’s device mounting and coupling with a small water basin. The ballistic device was coupled to the basin filled with degassed ultrapure water using a latex membrane covered with ultrasound gel and the contact pressure was applied with a spring. A fibre optic probe hydrophone was used for the sound field measurements. The pressure curves of every 10th shot were measured on the beam axis in a distance of 1mm to the membrane. The device was analysed at 3.5 bar with different pulse repetition rates (1 Hz, 10 Hz, 20 Hz). The test setup enables an easy handling and reproducible results at all pulse repetition rates. The ballistic device provides constant peak pressures over different frequencies. The small water basin has the advantage that the water quality is easy to control and the measuring process is fast and uncomplicated. Cavitation suppression requires a clean water basin filled with degassed ultrapure water kept at a constant, low temperature. The hybrid test bench can be used to easily study shock wave parameters of ballistic devices at high repetition rates.

In response to the drawbacks of low efficiency, cumbersome calculation, and easy-to-fall local optimal solutions in existing shallow water acoustic parameters inversion research, this paper proposes a shallow water acoustic parameters inversion method based on a feedback (BP) neural network model. Firstly, the theoretically predicted values of the shallow water sound pressure field are obtained through the fast field method (FFM). Secondly, a relationship model between the predicted sound pressure field and the inversion of ground sound parameter values is established based on the BP neural network model. Finally, the measured sound pressure field data are brought into the neural network model to obtain the inversion results. The application results of the method indicate that, compared to the classical simulated annealing (SA) algorithm, the BP neural network model converts the data-matching process of the optimization algorithm into the construction of a relationship model between the input data and the desired parameters, avoiding repeated matching and optimization processes. Therefore, it can directly, accurately, and efficiently output the inversion results. Under the premise of setting the same accuracy, the iteration number of the BP neural network model is reduced to 2% of the SA algorithm, cutting the calculation time to 30% of the SA algorithm. It has broad application prospects in shallow sea acoustic parameters inversion algorithms.

We consider a two-dimensional problem of diffraction of a harmonic sound wave emitted by a point sound source located near the sharp angle of an infinite wedge asymmetrically with respect to its faces. The boundary is considered as acoustically rigid. Using boundary integral equations for an asymmetric location of a source of sound, the problem is reduced to a system of two Fredholm integral equations of the second kind. The behavior of the solution by approaching the vicinity of the corner of the wedge is determined by the Meixner condition. The pressure value at the wedge end at the corner point is found in an explicit form. An asymptotic estimate of the behavior of the pressure function at infinity is performed. Discretization reduces the system of basic boundary integral equations to a system of linear algebraic equations. An "enhanced" discretization scheme with three intervals of different densities at each face is proposed. The pressure in a scattered field is constructed. [ABSTRACT FROM AUTHOR]

The ultrasonic Lamb wave detection principle can realize the noncontact measurement of liquid level in closed containers. When designing an ultrasonic Lamb wave sensor, it is vital to thoroughly study and select the optimal wedge size at the front of the sensor. In this paper, firstly, we select the best working mode of Lamb waves according to their propagation dispersion curve in aluminum alloy, and we obtain the best angle of wedge through experiments. Secondly, we study the impact of the size of the wedge block on the results, and we obtain the selection method of wedge block parameters. The evaluations show that, when the frequency–thickness product is 3 MHz·mm, the Lamb waves work in the A1 mode, and the experimental effect is the best. At this time, the incident angle of the ultrasonic wave is 27.39°. The wedge thickness should be designed to avoid the near-field area of the ultrasonic field, and we should choose the length as odd multiples of 1/4 wavelength. The rules obtained from the experiment can effectively select the best working mode for ultrasonic Lamb waves, while also providing a basis for the design of the wedge block size in a Lamb wave sensor. [ABSTRACT FROM AUTHOR]

The possibility of controlling localized fields in multimode shallow water waveguides based on the principle of interference invariance was studied. Within the framework of the numerical experiments in a wide frequency range of 100–350 Hz and range intervals of 10–100 km, the possibilities of focusing the sound field by wavefront reversal and controlling of the focusing of the focal spot by frequency tuning in shallow water waveguides was analyzed. The focal spot scanning was carried out by frequency tuning with a fixed distribution of the sound field at receiving and transmitting vertical antenna apertures. A comparative analysis of the features of focusing and focal spot control for summer and winter stratification of the water layer was carried out. It is shown that the parameters of the focal spot during frequency tuning were more stable in the winter waveguide. It is demonstrated that the sound frequency tuning had a piecewise continuous character and was carried out on a domain of one continuous track and jump-passing on the other track in accordance with the waveguide interference fringes in the range–frequency domain.

This paper presents a method for calculating the insertion loss of barriers on the ground. The method combines the classic imaging method for an analysis of sound propagation with the secondary source model for diffraction by barriers in the time domain, which is different from other frequency-domain methods. The validity of the proposed method is verified by comparing the theoretical results with those derived from the MacDonald method, and a valid approximation for the infinite barrier is discussed. [ABSTRACT FROM AUTHOR]

To study the transient characteristics of the sound field of the piezoelectric ultrasonic internal detector probe array, a finite element model of the probe array in the pipeline was established by COMSOL Multiphysics software, and the correctness was verified under experimental test conditions of the self-developed piezoelectric ultrasonic internal detector. Transient characteristics of the sound field under working conditions of single probe and double probes were studied respectively, and the variation of sound pressure at each point of the sound field under the two working conditions was obtained. The results show that the influence of echo signals on the signal reception of adjacent probes is small. When two adjacent probes work at the same time, the sound pressure superposition area is far away from the probe surface, and its influence on signal reception of adjacent probes can be easily eliminated. This model can determine the total sound field of a probe array in the pipeline under given conditions, and provide theoretical basis for the design of the piezoelectric ultrasonic internal detector.

The engine of a vehicle, particularly a passenger car, is one of the main sources of noise radiated into the environment and creates a noise load in residential areas, which has a negative impact on people. Experts in the field of acoustics perform computational and experimental acoustic studies both at the design stage, and at the stage of putting into production and directly operating the engine as part of the car to reduce engine noise. An important stage of acoustic research is the localization of the most intensely radiating noise of systems, mechanisms, nodes and engine parts. The article presents the results of experimental studies on localization of internal combustion engine noise sources of a LADA car.

Many studies have investigated the effects of music listening from the viewpoint of music features such as tempo or key by measuring psychological or psychophysiological responses. In addition, technologies for three-dimensional sound field (3D-SF) reproduction and binaural recording have been developed to induce a realistic sensation of sound. However, it is still unclear whether music listened to in the presence of 3D-SF is more impressive than in the absence of it. We hypothesized that the presence of a 3D-SF when listening to music facilitates listeners' moods, emotions for music, and physiological activities such as respiration rate. Here, we examined this hypothesis by evaluating differences between a reproduction condition with headphones (HD condition) and one with a 3D-SF reproduction system (3D-SF condition). We used a 3D-SF reproduction system based on the boundary surface control principle (BoSC system) to reproduce a sound field of music in the 3D-SF condition. Music in the 3D-SF condition was binaurally recorded through a dummy head in the BoSC reproduction room and reproduced with headphones in the HD condition. Therefore, music in the HD condition was auditorily as rich in information as that in the 3D-SF condition, but the 3D-sound field surrounding listeners was absent. We measured the respiration rate and heart rate of participants listening to acousmonium and pipe organ music. The participants rated their felt moods before and after they listened to music, and after they listened, they also rated their felt emotion. We found that the increase in respiration rate, the degree of decrease in well-being, and unpleasantness for both pieces in the 3D-SF condition were greater than in the HD condition. These results suggest that the presence of 3D-SF enhances changes in mood, felt emotion for music, and respiration rate when listening to music. [ABSTRACT FROM AUTHOR]

Many studies have investigated the effects of music listening from the viewpoint of music features such as tempo or key by measuring psychological or psychophysiological responses. In addition, technologies for three-dimensional sound field (3D-SF) reproduction and binaural recording have been developed to induce a realistic sensation of sound. However, it is still unclear whether music listened to in the presence of 3D-SF is more impressive than in the absence of it. We hypothesized that the presence of a 3D-SF when listening to music facilitates listeners’ moods, emotions for music, and physiological activities such as respiration rate. Here, we examined this hypothesis by evaluating differences between a reproduction condition with headphones (HD condition) and one with a 3D-SF reproduction system (3D-SF condition). We used a 3D-SF reproduction system based on the boundary surface control principle (BoSC system) to reproduce a sound field of music in the 3D-SF condition. Music in the 3D-SF condition was binaurally recorded through a dummy head in the BoSC reproduction room and reproduced with headphones in the HD condition. Therefore, music in the HD condition was auditorily as rich in information as that in the 3D-SF condition, but the 3D-sound field surrounding listeners was absent. We measured the respiration rate and heart rate of participants listening to acousmonium and pipe organ music. The participants rated their felt moods before and after they listened to music, and after they listened, they also rated their felt emotion. We found that the increase in respiration rate, the degree of decrease in well-being, and unpleasantness for both pieces in the 3D-SF condition were greater than in the HD condition. These results suggest that the presence of 3D-SF enhances changes in mood, felt emotion for music, and respiration rate when listening to music.

• Sound fields of complex forms as long subway platforms have been revealed. • Average SPL attenuations were greater than that in a corresponding long enclosure. • Average RT 30 was shorter than that in a corresponding long enclosure. • Geometric parameter as ground perimeter was negatively related to SPL attenuation. • The results are expected to provide references for soundscape in long enclosure. While the sound field characteristics of idealised long enclosures have been demonstrated, this study aimed to reveal the sound field of subway platforms with complex forms. The sound fields of ten actual subway platforms with complex forms were simulated, and the sound pressure level (SPL) attenuation and reverberation time (RT 30) were analysed. The results indicated that the average SPL attenuations of actual platforms with complex forms were 3.0 ∼ 7.7 dB greater than that with a corresponding idealised long enclosure, and the average RT 30 was 0.1 ∼ 0.5 s shorter. Regarding the receivers along the length, with the source-receiver distance increasing, the SPL attenuation showed an approximately logarithmic curve, and RT 30 presented a slightly increasing trend. The distance from the centre of each protruding space to the source was linearly correlated to both the average SPL attenuation and average RT 30 in each space. The geometrical parameters of ground perimeter, ground area, and average width were negatively correlated with the average SPL attenuation, and they were not significantly correlated with the average RT 30 for the actual subway platforms with complex forms. These results are expected to provide a reference for the design of underground subway platforms, acoustic environment controls, and soundscapes. [ABSTRACT FROM AUTHOR]

The ultrasonic Lamb wave detection principle can realize the noncontact measurement of liquid level in closed containers. When designing an ultrasonic Lamb wave sensor, it is vital to thoroughly study and select the optimal wedge size at the front of the sensor. In this paper, firstly, we select the best working mode of Lamb waves according to their propagation dispersion curve in aluminum alloy, and we obtain the best angle of wedge through experiments. Secondly, we study the impact of the size of the wedge block on the results, and we obtain the selection method of wedge block parameters. The evaluations show that, when the frequency–thickness product is 3 MHz·mm, the Lamb waves work in the A1 mode, and the experimental effect is the best. At this time, the incident angle of the ultrasonic wave is 27.39°. The wedge thickness should be designed to avoid the near-field area of the ultrasonic field, and we should choose the length as odd multiples of 1/4 wavelength. The rules obtained from the experiment can effectively select the best working mode for ultrasonic Lamb waves, while also providing a basis for the design of the wedge block size in a Lamb wave sensor.

This paper presents a method for calculating the insertion loss of barriers on the ground. The method combines the classic imaging method for an analysis of sound propagation with the secondary source model for diffraction by barriers in the time domain, which is different from other frequency-domain methods. The validity of the proposed method is verified by comparing the theoretical results with those derived from the MacDonald method, and a valid approximation for the infinite barrier is discussed.

Aim - justification of the method of monitoring the noise hazard of the environment. Objects and methods. A residential area with installed equipment to assess noise hazard; determination of the spectral composition of real noise. Results. The article establishes and substantiates the ratio between the intensity (pressure) of the sounds of different frequencies and the loudness of the perceived tones as the inverse law of Weber-Ovchinnikov The ways of studying the relief of the sound field and monitoring of the acoustic landscape of the environment are outlined.