Hasil untuk "Acoustics in engineering. Acoustical engineering"

Duroyon Matthieu, Susini Patrick, Misdariis Nicolas et al.

Electric vehicles are now part of the everyday automotive landscape. The resulting sonic experience is a major challenge for driver comfort. Despite this challenge being known, no solution reaching general consensus has yet been proposed. This might be due to the lack of a common culture of the sound or the expected sonic target in electric vehicles, in opposition to what existed for thermal engine. This work proposes a decisive tool to enhance communication on sound description in the electric car cabin. Inspired by soundscape studies, the methodology consists in using a semi-structured questionnaire oriented toward sound description and judgment with 12 acousticians working on electric vehicles. A verbal analysis identifies 11 specific sound names describing this sonic environment. Definitions that include three levels of description: causal, reduced and hedonic as well as audio illustrations, are proposed for each sound name. The lexicon is validated by the same group of acousticians and available online.

Banerjee Pragyan, Ojha Shivam, Kalimullah Nur M. M. et al.

This paper presents an approach to overcome the time-intensive nature of the Coulomb coupling imaging method by employing Generative Adversarial Networks (GANs) for data augmentation. Coulomb coupling, an experimental technique, is essential for visualizing ultrasonic wave propagation in piezoelectric materials and is valuable in various domains including materials research. It provides valuable insights such as finding mechanical properties and detecting anomalies in piezoelectric materials. However, the efficiency of this method is hindered by traditional time expansive point-by-point scanning. Integrating advanced machine learning into Coulomb coupling imaging has emerged as a promising solution to address this issue. Nonetheless, the lack of sufficient data has been a significant challenge. The key contribution is the use of GANs to create synthetic yet realistic images from a limited set of real data, effectively overcoming the issue of data scarcity. A large number of artificial images were successfully generated, expediting model training and enhancing generalization. This study is the first to use GANs in Coulomb coupling imaging, showing its transformative potential. By overcoming data limitations, the proposed approach enhances Coulomb coupling imaging and enables its integration with advanced technologies like AI-driven predictive modeling and real-time adaptive imaging. This opens new frontiers for applications in materials science and other imaging modalities.

Schmidt Thorsten, Müller Dirk

Heat pumps represent an essential component of the energy transition. While they are effective in generating heat, they also generate sound, which has the potential to cause annoyance. Therefore, it is essential to enhance the transparency of the sound behavior. Analyses were performed to identify the factors that influence sound levels at the component and system levels. A total of three refrigerant compressors were examined with the objective of determining the most acoustically efficient components currently available and the key factors influencing acoustics. Two low-noise axial fans are used to illustrate the differing sound characteristics when used in a heat pump application. Based on component tests and measurements at the heat pump system level, the speeds of the compressor and fan were confirmed as significant factors influencing the sound emissions of air-to-water heat pumps. In addition, the flow temperature and the operating point of the fan were identified as factors influencing. The results were employed to develop an acoustically improved heat pump demonstrator, which was based on a representative design. A sound model could be developed that is capable of describing the sound behavior for a wide range of operating conditions. This methodology allows for increased transparency in sound behavior. Different sound behaviors of heat pumps can be demonstrated on the basis of the model, and discussions on the definition of maximum sound specifications can be held on the basis of data. Sound emissions should not only be linked to heat output, as this increases the uncertainty of comparability. A transparent representation of the speeds is strongly recommended.

Thompson David J., Elliott Stephen J., Morfey Chris L. et al.

The Institute of Sound and Vibration Research (ISVR) at the University of Southampton was founded in 1963 from the Aeronautics Department. It grew rapidly into a leading centre for noise and vibration, combining research, teaching and consultancy. Although the initial focus was on the noise from aircraft and on their vibration-induced structural fatigue, there was already a recognition of the wider issues of sound in society and its subjective and medical effects. Consequently, the research interests of the ISVR quickly expanded to include aeroacoustics, automotive noise, structural dynamics, vibroacoustics, human responses to sound and vibration, data analysis and signal processing, active control, underwater acoustics and railway noise and vibration. The ISVR was a pioneer of university-industry collaboration, having many faculty positions that were supported by industrial funding as well as a strong consultancy activity. Unusual for an engineering department, teaching and research in clinical audiology featured strongly, and led to the establishment of a Cochlear Implant Centre in 1990. The paper gives a review of achievements of the ISVR in the 20th Century, identifying some of the main researchers and engineers who have inspired and guided its activities.

Terzakis Michail Evangelos, Van hoorickx Cédric, Hornikx Maarten

Environmental noise exposure has shown to have significant negative effects on people’s lives. In noise exposure studies, outdoor noise levels are usually preferred over indoor levels for investigating exposure-response relationships, introducing a systematic risk of bias. Hence, an outdoor-to-indoor sound propagation modelling framework is defined for estimating indoor noise levels based on outdoor levels. Particularly, by expressing outdoor and indoor sound propagation via energetic models and façade (multi-component and multi-layered) structures via computational sound insulation models (Transfer Matrix Method), outdoor-based indoor impulse responses can be generated. To validate the framework, a case study was conducted, showing that measured and simulated sound insulation were in good agreement. Finally, this framework was applied to generate datasets of outdoor and indoor noise levels (noise indicators) based on scenarios of outdoor environment, indoor environment, and façade structures. This allows the training of statistical learning approaches for estimating indoor noise levels and identifying important predictors. Results show that a random-forest approach outperforms a stepwise and a neural network approach across all the employed noise indicators (RMSE < 2 dB). These models enable the estimation of indoor sound exposure levels based on outdoor levels as well as the exploration of exposure-response relationships in locations with known built environment characteristics.

Antoni Jérôme, Duvauchelle Philippe, Ege Kerem et al.

The Laboratoire Vibrations Acoustique is a research unit of INSA Lyon, founded in the late 1960s to study vibrations and their consequences on noise emitted by machines and structures. The aim of this article is to review the historical contributions and main developments of the laboratory over the last fifty years. After examining the early years of the laboratory, the authors retrace the developments and key scientific contributions that have enabled it to gain renown at national and international levels in the field of vibration and acoustical engineering.

J. Mooney

This paper introduces a powerful approach to managing the complexities of modern building projects—Model-Based Systems Engineering (MBSE)—through the lens of acoustics consulting.  The growing complexity of modern building projects, particularly those requiring rigorous acoustical performance standards, demands innovative approaches to design, coordination, and verification. This paper explores the application of Model-Based Systems Engineering (MBSE) as a transformative tool for acoustics consultants and project managers alike. The method equips acoustics professionals with a systems engineering (SE) approach to manage complex acoustics requirements, ensuring traceability, performance verification, and interdisciplinary coordination throughout the project lifecycle. The method also serves as a pilot framework for project managers, providing a practical roadmap to integrate MBSE principles across all building systems in coordination with multidisciplinary teams. Through real-world examples and case studies, this paper illustrates how SE can improve project outcomes, streamline collaboration, and reduce the risk of performance failures. Readers will gain insights into structuring acoustics and other building requirements within an SE framework, leveraging Building Information Modeling (BIM) data, and efficiently managing design changes. For both acoustics consultant and project manager, this paper introduces valuable, actionable techniques to harness the power of systems engineering in complex building environments.

Warkentin Larissa, Denk Florian, Winkler Alexandra et al.

Speech recognition scores in noise can be affected by measurement conditions such as the spatial configuration, room acoustic properties, or the position and head orientation of a test person. This is critical when comparing repeated measurements, e.g., during hearing aid verification. While the basic effects of these factors are known, specific effect sizes for practically relevant configurations have not previously been reported. We investigated the effects of audiological test-room acoustics with low reverberation, and of head movements on speech-in-noise tests for typical spatial configurations. Speech-recognition thresholds (SRTs) and head movements were measured in 240 normal-hearing participants in six rooms for five loudspeaker configurations (S0N0, S0N±45, S0N±90, S0N180 and S±45N∓45). Additionally, head positions were reproduced with an artificial head, and using a binaural speech intelligibility model, binaural room impulse responses were measured to estimate the influence of head movements on the SRT. The results show that the effects of room acoustic properties and head movements varies greatly between spatial configurations. Head rotations around the vertical axis can affect speech recognition scores by up to 8 dB, most critically for the configuration S0N180. For spatially separated sound sources, different room acoustic conditions caused differences in SRT of up to 5 dB.

Kay L Gemba, Nicholas C Durofchalk, Derek R. Olson et al.

The Departments of Physics and Oceanography at the Naval Postgraduate School offer graduate programs leading to MS and PhD degrees. The acoustic track within the Department of Physics offers degrees in applied physics and engineering acoustics. Engineering acoustics degrees can be completed in either resident or distance learning modes. The department also offers stand-alone academic certificate programs in fundamentals of engineering acoustics, underwater acoustics, and sonar system applications, with a set of three certificates leading to a MS degree in engineering acoustics. MS and PhD programs are interdisciplinary, with coursework, traditional lectures, and laboratory exercises drawn primarily from the fields of physics, electrical engineering, and fundamental acoustics. The Oceanography Department offers degrees in both Physical Oceanography and a joint degree with Meteorology that are interdisciplinary. Both oceanography degrees contain a fundamentals of ocean acoustics course which is tightly coupled to the curriculum through dispersion relations. Connections between ocean processes and detection theory are made through a course on tactical oceanography. Subjects covered in both departments include fundamentals of acoustics; the generation, propagation, and reception of sound in the ocean; acoustic signal processing; and detection fundamentals.

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.

Ferrari Cesare Lupo, Cheer Jordan, Mautone Mario

Today’s cars must meet ever-higher acoustic standards, and so, to avoid compromising vehicle dynamics, handling performance and fuel consumption, standard passive methods alone do not provide sufficient performance. Active control solutions can provide a potential solution to this challenge, particularly at low frequency and such systems have been investigated for application to small cars, SUVs and luxury vehicles. These vehicles are generally characterised by fairly slow dynamics and limited noise emission and, therefore, this paper explores the challenging application of active noise control to a two-seat super sports car equipped with a naturally aspirated engine. This work aims to track and then control sounds characterised by extremely rapid frequency variation rates, up to peaks of over 80 Hz/s, and high sound pressure levels. A multi-channel, multi-order FxLMS based control system has been implemented, which has been modified to optimise performance for this application by including both convergence gain and leakage scheduling, to achieve effective control at the driver’s and passenger’s ears. To evaluate the performance of the controller, its performance has been simulated when applied to measurements taken under several vehicle manoeuvres, ranging from conventional constant engine speed to very fast engine run-ups. From the presented results, it is shown that the system can obtain high levels of control during the manoeuvre set, with the controller reducing the overall sound pressure level by more than 10 dB at certain frequencies when analysing a single order, and it reduces the overall loudness by around 5% in all of the analysed cases.

Guo Yao, Zhu Hongyan

A random finite set-based sequential Monte–Carlo tracking method is proposed to track multiple acoustic sources in indoor scenarios. The proposed method can improve tracking performance by introducing recognized speaker identities from the received signals. At the front-end, the degenerate unmixing estimation technique (DUET) is employed to separate the mixed signals, and the time delay of arrival (TDOA) is measured. In addition, a criterion to select the reliable microphone pair is designed to quickly obtain accurate speaker identities from the mixed signals, and the Gaussian mixture model universal background model (GMM-UBM) is employed to train the speaker model. In the tracking step, the update of the weight for each particle is derived after introducing the recognized speaker identities, which results in better association between the measurements and sources. Simulation results demonstrate that the proposed method can improve the accuracy of the filter states and discriminate the sources close to each other.

Lafarge Denis, Nemati Navid, Vielpeau Stéphane

We present a new stochastic simulation method for determining the long-wavelength effective dynamic bulk modulus of gases, such as ambient air, saturating porous media with relatively arbitrary microgeometries, i.e., simple enough to warrant Biot’s simplification that the fluid and solid motions are quasi-incompressible motions at the pore scale. The simulation method is based on the mathematical isomorphism between two different physical problems. One of them is the actual Fourier heat exchange problem between gas and solid in the context of Biot theory. The other is a diffusion-disintegration-controlled problem that considers Brownian motion of diffusing particles undergoing radioactive-type decay in the pore volume and instant decay at the pore walls. By appropriately choosing the decay time and the diffusion coefficient, the stochastic algorithm we develop to determine the average lifetime of the diffusing particles, directly gives the effective apparent modulus of the saturating fluid. We show how it leads to purely geometric stochastic constructions to determine a number of geometrical parameters. After validating the algorithm for cylindrical circular pores, its power is illustrated for the case of fibrous materials of the type used in noise control. The results agree well with a model of the effective modulus with three purely geometric parameters of the pore space: static thermal permeability divided by porosity, static thermal tortuosity, and thermal characteristic length.

Poirier-Quinot David, Lawless Martin S.

For augmented reality experiences, users wear head-mounted displays (HMD) while listening to real and virtual sound sources. This paper assesses the impact of wearing an HMD on localization accuracy of real sources. Eighteen blindfolded participants completed a localization task on 32 loudspeakers while wearing either no HMD, a bulky visor HMD, or a glass visor HMD. Results demonstrate that the HMDs had a significantly impact on participants’ localization performance, increasing local great circle angle error by 0.9°, and that the glass visor HMD demonstrably increased the rate of up–down confusions in the responses by 0.9–1.1%. These results suggest that wearing an HMD has a sufficiently small impact on real source localization that it can safely be considered as an HMD-free condition in most but the most demanding AR auditory localization studies.

Paul H. Scarbrough, C. Blair

Acoustical design for performance spaces is generally considered to be both an art and a science. Part of the science involves assuming an engineering mindset when deciding where to draw the line with respect to criteria for room acoustics, sound isolation, HVAC noise control, and other issues. When does sound from the outside truly become intrusive? How quiet is quiet enough when it comes to HVAC noise? Renovation projects often impose practical constraints that preclude aiming for extreme degrees of sound isolation or HVAC noise control. Even well-funded new construction projects sometimes require careful consideration of how to expend project resources to best effect. This paper will explore the authors' experiences making such decisions on a range of projects involving new construction (Las Vegas’ Smith Center for the Performing Arts), historic restoration (Cincinnati Music Hall), adaptive re-use (Milwaukee’s Bradley Symphony Center), and substantial reconstruction (David Geffen Hall at Lincoln Center).

W. D. Fonseca, E. Brandão, P. H. Mareze et al.

Acoustics is a broad field of knowledge that extends branches all over the physics of wave phenomena, psychology, natural sciences, and engineering. It is taught, in general, as part of engineering, physics, or architecture programs, or even in graduate programs specialized in the theme. In Brazil, acoustics was taught in graduate programs, until the creation of Acoustical Engineering in 2009, at the Federal University of Santa Maria, an integral undergraduate program dedicated to acoustics, audio, and vibration (lasting ten semesters). This article presents its complete academic program, its creation process, and the professional establishment of the acoustical engineer. In the following, the program of study and subjects are elucidated and detailed, and the teaching methodologies used are also discussed. The program employs several active learning strategies, like project-based learning, aiming to transform abstract into concrete knowledge. The interaction of the university, the acoustical engineer, and society is also presented and clarified. The placement of graduates in fields and their workplaces are presented as outcomes. As a fundamental part of the engineer's formation, the infrastructure used, whether state-of-the-art or cost-effective equipment, is detailed in the context of teaching and research. Finally, some of the ongoing research projects of the students are described.

O. Godin, K. Gemba

The Departments of Physics and of Electrical and Computer Engineering at the Naval Postgraduate School offer graduate programs in acoustics leading to MS and PhD degrees in applied physics and engineering acoustics. Engineering acoustics degrees can be completed in either traditional or distance learning modes. The departments also offer stand-alone academic certificate programs in fundamentals of engineering acoustics, underwater acoustics, and sonar system applications, with a set of three certificates leading to a MS degree in engineering acoustics. MS and PhD programs are interdisciplinary, with courses and laboratory work drawn principally from the fields of physics and electrical engineering. Subjects covered include waves and oscillations; fundamentals of physical and structural acoustics; the generation, propagation, and reception of sound in the ocean; civilian and military applications of sonar systems; and acoustic signal processing. Topics of recent theses and dissertations include development and field testing of novel sensors for atmospheric and ocean acoustics, modeling and measurements of ambient noise and sound propagation in the ocean, sound scattering in underwater waveguides, acoustic vector sensors and vector field properties, acoustic communications, noise interferometry, time reversal in acoustics, geo-acoustic inversion, acoustic remote sensing of the ocean, and acoustics of autonomous underwater and aerial vehicles.

Maurerlehner Paul, Schoder Stefan, Tieber Johannes et al.

The hybrid aeroacoustic approach is an efficient way to address the issue of the disparity of scales in Computational AeroAcoustics (CAA) at low Mach numbers. In the present paper, three wave equations governing propagation of flow-induced sound of low Mach number flows, namely the Perturbed Convective Wave Equation (PCWE), Ribner’s Dilatation (RIB) equation, and Lighthill’s wave equation, are applied using the Finite Element Method (FEM). An airflow through a circular pipe with a half-moon-shaped orifice at three operating flow speeds is considered, where validation data from measurements on a dedicated test rig is available. An extensive analysis of the flow field is provided based on the results of the incompressible flow simulation. The resulting acoustic source terms are investigated, and the relevant source term contributions are determined. The results of the acoustic propagation simulations revealed that the PCWE and RIB are best suited for the present task. The overall deviation of the predicted pressure spectra from the measured mean values amounted to 2.26 and 2.13 times the standard deviation of the measurement compared to 3.55 for Lighthill’s wave equation. Besides reliably predicting the flow-induced sound, the numerical procedure of source term computation is straightforward for PCWE and RIB, where the source term contributions, shown to be relevant, solely consist of time derivatives of the incompressible pressure. In contrast, the Lighthill source term involves spatial derivatives and, thus, is strongly dependent on the spatial resolution and the numerical method actually used for approximating these terms.

Biberger Thomas, Ewert Stephan D.

Auditory perception involves cues in the monaural auditory pathways, as well as binaural cues based on interaural differences. So far, auditory models have often focused on either monaural or binaural experiments in isolation. Although binaural models typically build upon stages of (existing) monaural models, only a few attempts have been made to extend a monaural model by a binaural stage using a unified decision stage for monaural and binaural cues. A typical prototype of binaural processing has been the classical equalization-cancelation mechanism, which either involves signal-adaptive delays and provides a single channel output, or can be implemented with tapped delays providing a high-dimensional multichannel output. This contribution extends the (monaural) generalized envelope power spectrum model by a non-adaptive binaural stage with only a few, fixed output channels. The binaural stage resembles features of physiologically motivated hemispheric binaural processing, as simplified signal-processing stages, yielding a 5-channel monaural and binaural matrix feature “decoder” (BMFD). The back end of the existing monaural model is applied to the BMFD output and calculates short-time envelope power and power features. The resulting model accounts for several published psychoacoustic and speech-intelligibility experiments and achieves a prediction performance comparable to existing state-of-the-art models with more complex binaural processing.

Lladó Pedro, Hyvärinen Petteri, Pulkki Ville

Auditory localisation accuracy may be degraded when a head-worn device (HWD), such as a helmet or hearing protector, is used. A computational method is proposed in this study for estimating how horizontal plane localisation is impaired by a HWD through distortions of interaural cues. Head-related impulse responses (HRIRs) of different HWDs were measured with a KEMAR and a binaural auditory model was used to compute interaural cues from HRIR-convolved noise bursts. A shallow neural network (NN) was trained with data from a subjective listening experiment, where horizontal plane localisation was assessed while wearing different HWDs. Interaural cues were used as features to estimate perceived direction and position uncertainty (standard deviation) of a sound source in the horizontal plane with the NN. The NN predicted the position uncertainty of localisation among subjects for a given HWD with an average estimation error of 1°. The obtained results suggest that it is possible to predict the degradation of localisation ability for specific HWDs in the frontal horizontal plane using the method.