Acoustic Model Research Articles

Method of Satisfaction Based On-board Acoustic Comfort Classification and Its applications

Acoustic comfort is an important factor that passengers and crew usually consider for their on-board wellness. The classification is an efficient way to show the level of acoustic comfort on board. Most of the existing classification approaches of on-board noise in different spaces are based on the decibel based indicators which describes the loudness. However, acoustic comfort is not only relevant to decibel based indicators but also perceptual attributes such as timbre and pitch. In order to provide more perceptual support, a satisfaction based classification method for acoustic comfort is modified, determining the limits of the noise in different task-oriented spaces on board. Perceptual assessments were carried out to obtain numerical values for acoustic comfort as noise comfort index (NCI) and measured satisfaction (SM) of each noise sample. Analysis made on these two descriptors indicated that the NCI has a strong relationship with SM. Therefore, satisfaction can be regarded as a basic perceptual guideline to classify the acoustic comfort and determine the limits of each level for each task-oriented space. A linear acoustic comfort model was established to predict the NCI based on the acoustic parameters. Comparison with the previous classification of on-board noise showed that there is a mismatch between the NCI and sound pressure level (SPL), and NCI can not be fully represented by SPL.

Voice Recordings from Short Mobile Sessions versus Clinical Interviews for Mental Illness Screening: A Comparative Study with Deep Transfer Learning

The prevalence of mental illness symptoms is increasing. While questionnaires are traditionally used, prior research applied machine learning to clinical interview recordings conducted by a virtual agent for depression screening. In this research, we compare their screening ability with brief mobile voice recordings. The latter reduces completion time while increasing access to screening. We collected 546 mobile voice recordings in response to four clinical interview questions from over 200 crowd-sourced adults reporting English fluency. We also collected responses to traditional screening questionnaires to use as labels in the classifiers. We extract textual transcripts from these voice recordings, facilitating both unimodal and multimodal classification. We compose acoustic and language representation models into deep learning architectures fine-tuned for mental illness screening. In our study, we compare the mental illness screening ability of four questions from mobile voice recordings and complete clinical interviews. When screening for depression, the brief mobile voice responses to individual questions proved as good or better for half of the interview questions. Overall, we achieved AUC of 0.76 for depression, 0.76 for anxiety, and 0.81 for suicidal ideation screening using our mobile voice recordings. Our findings can help guide the development of efficient and effective mental illness screening technologies.

Automated acoustic voice screening techniques for comorbid depression and anxiety disorders.

Anxiety disorders (AD) and major depressive disorders (MDD) are growing in prevalence, yet many people suffering from these disorders remain undiagnosed due to known perceptual, attitudinal, and structural barriers. Methods, tools, and technologies that can overcome these barriers and improve screening rates are needed. Tools based on automated analysis of acoustic voice could help bridge this gap. Comorbid AD/MDD presents additional challenges since some effects of AD and MDD oppose one another. Here, acoustic models that use acoustic and phonemic data from verbal fluency tests to discern the presence of comorbid AD/MDD are presented, with the best results of F1 = 0.83.

Analytical and experimental study on acoustic-vibration characteristics of double-helical planetary gear transmission systems with multi-field coupling effect

The acoustic vibration characteristics play a crucial role in determining the performance of aero double-helical planetary gear transmission systems. Considering the coupling effect among temperature, fluid, and structure in double-helical planetary gear transmission systems, an improved mesh stiffness model is constructed in this paper, which also considers the fractal tooth, tooth friction, thermal expansion, and load-sharing of “oil film-asperity”. Based on the study of mesh stiffness of fractal tooth, a centralized parametric dynamic model is established, considering the influence of friction excitations, transmission error, and tooth clearance. The bearing stiffness and the obtained dynamic mesh forces are then used as excitation sources to calculate the vibration of the gear system with its housing. Furthermore, the housing vibration displacement in the frequency domain is used as the boundary condition of the acoustic boundary element model to calculate the housing surface sound pressure and the field point sound pressure of the gearbox. Finally, experiments on vibration and acoustics are conducted to verify the correctness of the theoretical investigation. The results show that the mesh stiffness of fractal double-helical gear pairs with multi-field coupling effect is closer to the simulation value of the finite element method (FEM), the tested vibration is close to the value of the simulation, and the tested sound pressure level is close to the value obtained by the boundary element method (BEM), which indicates the validity of the proposed methods.

Low-Loss SAW Devices for Sensing Liquid Phase Based on Acoustic Model Conversion

Low-Loss SAW Devices for Sensing Liquid Phase Based on Acoustic Model Conversion

An Approach to Evaluate the Fatigue Life of the Material of Liquefied Gases’ Vessels Based on the Time Dependence of Acoustic Emission Parameters: Part 1

In the first part of this article devoted to the assessment of the fatigue life of structural steels at low temperatures, a study was conducted on the effect of pre-cycling in a low-cycle fatigue mode on the time dependences of acoustic emission parameters. Commonly used St-3 steel was tested at −60 °C with varying durabilities, after which it was fractured once during static tests. The multilevel acoustic model used made it possible to estimate the structural parameter at the stage of elastoplastic deformation. The stage of active development of microcracks and their coalescence corresponds to a homogeneous fracture with stable acoustic emission characteristics (signal duration, amplitude variation coefficient, etc.). It was shown that regardless of the maximum voltage (460, 480, and 500 MPa) in the cycle and the operating times of up to 0.3, 0.5, and 0.7, the structural parameter remains within the known limits. The parameters of the Weibull law distribution and the logarithmically normal distribution for the coefficient γ were obtained, theoretical and calculated fatigue curves were plotted, and a method was proposed for evaluating the number of cycles before fracture under irregular loading conditions in the real operation of pressure vessels based on the “rainflow” cycles counting method.

Hybrid Acoustic Metamaterial Based on Absorption Accumulation Peaks for a Broad Sound Energy Control

Controlling sound energy over a wide spectrum of frequencies through structures with a subwavelength scale is a challenge in acoustics. In this sense, a hybrid acoustic metamaterial model (HAMM) that acts over a wide frequency spectrum is presented. The structure consists of a combination of a porous layer and an acoustic metamaterial (AMM). Two samples are evaluated to establish effective control of sound energy () between 450 and 6400 Hz with the structure reaching a maximum ratio of . Furthermore, the behavior of sound waves in the structure is explored through analysis of the sound pressure field, instantaneous particle velocity, and thermoviscous dissipation. One of the highlights of the HAMM is that it is composed of an AMM that has a low phase velocity. Thus, the ultra‐slow sound in part of the structure allows the low‐frequency resonance frequency to be shifted to lower frequencies. Another characteristic is that because of the accumulation of absorption peaks below the bandgap of the AMM, a low‐frequency broadband absorption is guaranteed. Therefore, this work contributes substantially to advances in the area of sound energy control over a wide spectrum of frequencies through the use of different combined acoustic materials.

Optimization of the convergent-divergent nozzle tip and reducing the acoustic energy

One of the practical components that can be found in aircraft engines, the Delaval nozzle, works to improve the aircraft's performance in terms of its stability and its capacity to manoeuvre at different speeds of operation. This research concentrates on the acoustic behaviors shown by this nozzle during the transition from low rate to sonic speed. The modification of the nozzle tip at various degrees of inclination on the transition velocity is the procedure used to minimize the amount of acoustic energy emitted. The acoustic behavior is analyzed based on the FW-H acoustics model utilized, and the optimization problem is solved using the practical eddy simulation approach in CFD. The acoustic Power, measured in dB, is estimated at various angles on the nozzle tip, and the performance of the Delaval nozzle is used to show how the redesigned nozzle tip affects the nozzle's acoustic behavior.

MODELS FOR PREDICTING SOUND ABSORPTION OF POROUS MATERIALS

Porous materials are widely used in the field of noise control. The acoustic properties of these materials are best characterized by the sound absorption coefficient, which can be predicted using different mathematical models presented in this paper: empirical, phenomenological, and statistical. Optimization models based on biologically inspired algorithms were used to determine the non-acoustic parameters of the acoustic models. In addition to mathematical models for predicting acoustic parameters of porous materials, the paper also presents models for identifying non-acoustic parameters that are input parameters of empirical and phenomenological models. Air flow resistance is one of the most significant non-acoustic parameters of porous materials, and its values shown in this paper were measured according to the SRPS EN ISO 9053-1:2019 method. In empirical models, resistance to airflow is the only input parameter, while in phenomenological and optimization models it is one of several input parameters that establish a connection between microstructure and acoustic properties of porous materials. Based on the experimental values of the sound absorption coefficient, the non-acoustic parameters of the phenomenological models were determined using biologically inspired optimization algorithms. Statistical models are based on ANOVA analysis and determination of the sound absorption coefficient's dependence on the material layer's thickness and frequency. Predictions of the sound absorption coefficient of open-cell polyurethane foam were determined using the above models and are compared with pipe impedance measurements. In this way, the accuracy of the prediction of mathematical models for determining sound absorption was established. In addition, this research shows that low-density open-cell polyurethane foams have good sound absorption performance over a wide frequency range, and as such can be used for noise protection.

Underwater sound absorption characteristics of the acoustic metamaterials with multiple coupling substructure

The lateral plates are usually used in the field of structural design of acoustic metamaterials (AMs), which can realize the control of AMs on sound waves. Presently, researches on the application of AMs with lateral plates mainly focus on the regulation of sound waves in air media, and rarely involve the research on their underwater acoustic properties. Therefore, a composite acoustic structure is designed by inserting regularly distributed lateral plates into the viscoelastic rubber, and then, the AMs with multiple coupling substructure (AMs-MCS) can be obtained through combining the local resonance structure and functional gradient structure. Based on underwater acoustic calculation model for the functional gradient acoustic structure established by grade finite element method (G-FEM), the underwater sound absorption characteristics of the AMs-MCS are studied, and the influence of each substructure on the acoustic performance of the AMs-MCS is explored. Numerical results indicate inserting gradient-distributed multiple lateral plates inside the homogeneous acoustic structure can improve the sound absorption performance of the acoustic structure in the mid-and high-frequency ranges and the sound absorption frequency band of the acoustic structure can be effectively broadened. Moreover, the sound absorption coefficient of the AMs-MCS is greater than 0.8 at 500Hz-10 kHz, and the average sound absorption coefficient reaches 0.893, thus achieving low-frequency and broadband sound absorption performance.

Acoustical modeling and analysis of proton-exchange membrane fuel cell stack anode exhaust gas from the perspective of ultrasound testing

Abstract Proton-exchange membrane fuel cells are widely utilized in transportation and stationary power generation applications due to their high energy conversion efficiency, substantial power density, and zero emissions. To address the requirements for internal status monitoring and hydrogen purge management in the hydrogen supply subsystem of automotive fuel cell systems, this paper proposes an innovative online monitoring scheme for real-time measurement of the anode exhaust mixture concentration from the fuel cell stack, utilizing an ultrasonic flowmeter. This scheme offers high measurement accuracy, short sampling intervals, simple configuration, and low cost. An acoustic analysis model of the anode exhaust gas was developed to systematically evaluate the influence of environmental parameters such as temperature, pressure, and humidity on the ultrasonic flowmeter’s measurement. Additionally, an ultrasonic flowmeter prototype was constructed based on this acoustic model, and the accuracy of its flow rate and concentration measurements was validated using standard gases. The results indicate that, without a humidity sensor, the absolute error in hydrogen concentration can reach 7 vol%, while the absolute error in nitrogen concentration can exceed 11 vol%. Therefore, integrating additional sensors is essential for improving the accuracy of concentration calculations for the anode exhaust gas components. The relative error in flow measurement with the ultrasonic flowmeter prototype is consistently below 5%, and the absolute error in concentration measurements is less than 1%, reflecting the effectiveness and feasibility of the proposed method. Furthermore, this paper outlines a calculation method for converting sensor feedback into the mass flow rates of individual gas components in the mixture. This work offers a novel theoretical and practical framework for enhancing real-time internal status monitoring and hydrogen purge management in fuel cell systems, which is expected to significantly improve the reliability, stability, and fuel economy of automotive fuel cell systems in the future.

Investigating the influence of a bubble curtain on the underwater sound wave field generated by offshore pile driving.

Pile driving for offshore wind turbines typically generates high sound levels in the water column. Bubble curtains are frequently employed to protect marine fauna. This study aims to investigate the effect of a bubble curtain on the generated sound wave field. A recently developed seismo-acoustic model was extended by incorporating an established acoustic model of the bubble curtain. Subsequently, a detailed analysis of the sound wave field at an offshore wind farm construction site was conducted using both simulated and measured data. The results indicate a distance- and depth-dependent insertion loss, with reductions of approximately 2 to 4 dB observed at greater distances from the pile. For a more detailed analysis, a metric based on the concept of transmission loss was introduced. This demonstrates that the insertion loss caused by a bubble curtain can be formulated as a sum of two components: the loss due to the interaction between the bubbles and the sound wave field, and the altered bottom loss resulting from the scattering of the sound wave as it passes through the bubble curtain. Analysis of the simulation data highlights that sound scattering and the resulting altered bottom loss significantly contribute to the efficiency of the bubble curtain.

Insight on the complete process of photoacoustic generation and propagation of cerebrovascular in brain via multi-physics coupling method

The presence of the skull hinders photoacoustic imaging from being used for brain imaging. In order to understand the mechanism of photoacoustic signal generation of cerebrovascular in the presence of skull, a photoacoustic model of cerebrovascular was established by using COMSOL Multiphysics to achieve the visualization of the whole process of the generation and transmission of the cerebrovascular photoacoustic signal. The diffusion equation is approximated by the partial differential equations in the form of coefficients in the mathematical module of COMSOL to describe laser propagation in brain tissue. The light energy absorbed by the gray matter and blood vessels was used as a heat source, and the biological heat transfer module of COMSOL Multiphysics was used to describe the instantaneous temperature rise of gray matter and blood vessels. A thermal strain model was constructed by the solid mechanics module to visualize the surface displacement caused by the adiabatic expansion of blood vessels. The photoacoustic signal is generated by the surface displacement of the vessel, and the propagation of the photoacoustic signal is visualized using a transient pressure acoustic model of COMSOL Multiphysics. This visualization study provides theoretical guidance for the research and application of photoacoustic imaging in brain structural and functional imaging.

Intra-layer and inter-layer monitoring of laser powder bed fusion defects based on airborne acoustic and gn-Res model: pore and deformation

ABSTRACT Macroscopic deformation and microscopic pores are the main defects affecting the comprehensive performance of laser powder bed fusion (LPBF) parts. The LPBF process involves highly coupled multiple physical mechanisms over a wide time scale, making it difficult to obtain strongly correlated defect characteristics and achieve online monitoring. Thus, this study proposes an acoustic-based macro–micro defect synchronous monitoring technology. It enables monitoring by analysing process information progressively from intra-layer to inter-layer. The research identifies that high energy density leads to deformation defects, with helical scan strategy energy fluctuations exacerbating deformation. A correlation between keyhole pores and high-frequency signal components allows quantitative pore analysis directly from acoustic signals. Furthermore, an intelligent diagnosis model (gn-Res_SC) is proposed, incorporating high-order information interaction and residual structure for in-depth process analysis. The model demonstrates superior performance with accuracy (90.70%), recall (90.70%) and F1-score (90.40%) in LPBF acoustic monitoring signal evaluation.

Influence of Detail Level in Acoustic Modeling of Heritage Buildings. Case of the Lonja de los Mercaderes in Valencia

Acoustic modeling of heritage buildings presents a significant challenge due to the architectural complexity of these spaces and the need to preserve their authenticity. In particular, the precision of the virtual model in historical environments largely depends on the level of detail applied during simulation. This study examines the influence of detail level in acoustic modeling applied to the Lonja de los Mercaderes in Valencia, a prominent example of Gothic civil architecture in Europe. Using ODEON software, three virtual models of the main hall were developed with varying levels of detail, from a high-precision model to a simplified representation. The results show that a highly detailed model increases computational costs, while a reduction in detail leads to greater dispersion in results, especially at low frequencies. This research highlights the importance of finding an appropriate balance in detail level, providing reliable acoustic estimates without compromising efficiency. These findings contribute to ongoing discourse on heritage conservation practices, emphasizing how simulation technologies can aid in preserving acoustic integrity while addressing practical limitations. The conclusions have implications for the application of simulation technologies in other highly complex heritage buildings.

Dynamic behaviors for the acoustic model with variable coefficients and nonautonomous damping

Dynamic behaviors for the acoustic model with variable coefficients and nonautonomous damping

Innovative Cavity Modeling for Centrifugal Compressors Aeromechanical Analysis

Abstract Centrifugal compressor aeromechanics is playing an increasingly important role in the energy transition scenario, especially when operating with low-molecular-weight gases, such as hydrogen. For these machines, maximum impeller tip speeds are limited by structural requirements and so aeromechanical assessment must be included from the preliminary design stages. When performing forced response analysis of centrifugal impellers, it is mandatory to consider the contribution of the unsteady forces acting within front and rear cavities. The flow field inside the cavities has different time and length scales compared with the main flow field, and from a modeling standpoint, seal regions have to be included in the computational domain: this means that a comprehensive computational fluid dynamics (CFD) simulation may require substantial efforts for the setup and high computational time and resources. In this context, this article presents an acoustic analytical model for predicting pressure perturbation within centrifugal compressor cavities without solving them with unsteady CFD approaches. The model is fed with appropriate boundary conditions to be applied at the entrance of the cavities and analytically solves the pressure perturbation distribution in an annular environment. To validate the presented analytical model, unsteady calculations were performed on impeller-vaned diffuser domains with cavities at different operating conditions, and the unsteady pressure field in the cavities was used as a target solution. The comparison between the analytical model results and the CFD solution shows a very good agreement for all the different blade passing frequencies under investigation, paving the way for accurate aeromechanical evaluations in the preliminary design phase when complete unsteady CFD simulations are not compatible with design timing.

Statistical Analysis of Intermediate Frequency Underwater Acoustic Communication Channel Characteristics in Deep-Sea Sound Channel Axis

Based on experimental data from the deep-sea sound channel axis in the Western Pacific, the statistical distribution law of cluster structure and channel delay spread characteristics are analyzed for three typical receiving depths near the sound channel axis in this paper. A ray theory-based underwater acoustic channel model is used to explain the variations in channel parameters over time and the receiving depth. The results indicate that the underwater acoustic communication channel at the channel axis depth over a 20-km range exhibits a clustered structure that depends on the emission angles of sound rays. For the amplitude characteristics, the amplitude of each cluster follows an inverse Gaussian distribution, with the maximum average amplitude observed when the receiver and transmitter depths are similar. The amplitude of each cluster fluctuation decreases as the receiving depth increases. Regarding delay spread characteristics, the delay spread of each cluster, as well as the maximum and root mean square delay spread of the channel, conform to a Gaussian mixture distribution. The mean and fluctuation of the delay spread parameters increase with the receiving depth. Variations in the cluster structure and channel delay spread characteristics above are primarily attributed to the time-varying sound speed along the propagation paths of sound rays emitted at small upward angles.

Complex Crater Collapse: A Comparison of the Block and Melosh Acoustic Fluidization Models of Transient Target Weakening

AbstractThe collapse of large impact craters requires a temporary reduction in the resistance to shear deformation of the target rocks. One explanation for such weakening is acoustic fluidization, where impact‐generated pressure fluctuations temporarily and locally relieve overburden pressure facilitating slip. A model of acoustic fluidization widely used in numerical impact simulations is the Block model. Simulations employing the Block model have successfully reproduced large‐scale crater morphometry and structural deformation but fail to predict localized weakening in the rim area and require unrealistically long pressure fluctuation decay times. Here, we modify the iSALE shock physics code to implement an alternative model of acoustic fluidization, which we call the Melosh model, that accounts for regeneration and scattering of acoustic vibrations not considered by the Block model. The Melosh model of acoustic fluidization is shown to be an effective model of dynamic weakening, differing from the Block model in the style of crater collapse and peak ring formation that it promotes. While the Block model facilitates complex crater collapse by weakening rocks deep beneath the crater, the Melosh model results in shallower and more localized weakening. Inclusion of acoustic energy regeneration in the Melosh model reconciles required acoustic energy dissipation rates with those typically derived from crustal seismic wave propagation analysis.

A passive sonar based underwater acoustic channel model for improved search and rescue operations in deep sea

A passive sonar based underwater acoustic channel model for improved search and rescue operations in deep sea