Hasil untuk "Acoustics in engineering. Acoustical engineering"

M.E. Delany, E.N. Bazley

Gu Jun-Fei, Yin Jia-Hao, Li Xue-Dong et al.

This study proposes a gradient radial seismic metamaterial that integrates typical engineering core geometries with particle swarm optimization (PSO) algorithm and placement optimization to realize low-frequency, broadband surface-wave attenuation in compact footprints. Under an equal-area constraint and a band-diagram objective focused on the first two bands, the T-shaped unit emerges as the most effective core, and a front-rear graded assembly superposes Bragg-scale gaps to span 5–35 Hz, aligning with the dominant frequencies of destructive surface waves. Cylindrical-coordinate finite-element dispersion analysis, 3D frequency-domain response spectra, and time-domain excitation with the 1984 Bishop record collectively verify marked reductions in stress, displacement, and peak acceleration within the target frequency, confirming engineering feasibility. The approach addresses scalability and material-use constraints while lowering onset frequency and widening the primary band gap, offering a practical pathway for building-level seismic shielding.

Bonomo Lucas Araujo, Brambley Edward James, Cordioli Julio Apolinário

Impedance eduction methods are the current standard approach to measure the impedance of acoustic liner under sheared grazing flow. The dedicated facilities for these methods consists on a waveguide with rectangular cross-section, which implies a sheared grazing flow. A current debate in the literature is the effect of this sheared flow in the impedance eduction methods. We assess the impact of the flow profile shape on acoustic propagation in a two-dimensional duct within the typical operating range of impedance eduction facilities. Firstly, a numerical experiment is proposed in which the Pridmore–Brown equation is assumed to represent the true physical behaviour, and is used with both simplified flow profiles commonly used in the literature and a realistic representation of a turbulent boundary layer using a van Driest universal law of the wall model. The data from these numerical experiments are then used with a traditional impedance eduction process, and the resulting variation in obtained impedances are investigated. Secondly, we apply a less-traditional impedance eduction method that incorporates the sheared velocity profile to data obtained from real-world experiments. The results suggest that the Ingard–Myers boundary condition remains a good approximation to a realistic boundary layer profile, such as the universal law of the wall, at least in the two-dimensional case. However, it is also shown that the simplified flow profiles often used in the literature can lead to significant deviations from the results obtained using a realistic velocity distribution.

Stärz Felix, Van De Par Steven, Roßkopf Sarah et al.

In this study, auralisations of a real room were compared to the actual acoustics of that room using listening tests. Participants sat in a room and wore a combination of a head-mounted display (HMD) and headphones, and rated different room-acoustic attributes for an auralised loudspeaker and the corresponding real loudspeaker in the room, without knowing what they were actually listening to. Auralisations were created with varying levels of detail using either measured or simulated binaural room impulse responses (BRIRs), which were based on individual or generic Head-and-Torso simulator (HATS) data. Besides different levels of detail, some manipulations of the room acoustics were introduced into the simulation to better contextualise the results. The results show a good agreement between the auralised and the real room for both measured and simulated BRIRs. The observed deviations based on the different levels of detail were generally smaller than the introduced room acoustic manipulations. Individual head-related transfer function (HRTF) data had no real benefit, and the passive influence of the HMD headphone combination had no effect on the ratings.

Meza-Pérez Amaury, Stoppani George, Viala Romain et al.

During the Bilbao project, six violins were built with systematic geometry control in order to investigate the influence of the plate thickness on the dynamics, sound and playing characteristics of the complete instruments. To this end, three violins with medium backs, each paired with a thin, normal, or thick top and three with medium tops, each paired with a thin, medium, or thick back were made. Despite careful control and reduction of the influence of handwork by a numerically controlled machining cutting means on the outside of the plates, there remains various sources of variability, in particular in the wood properties. In order to separate the effect on the vibratory behavior of the intentional thickness variations from irreducible variability in wood properties and geometric tolerance, a complete finite element model is being developed using COMSOL software. This model takes into account the geometry of the Bilbao project violins while the wood properties are obtained by optimising the numerical vibratory behavior to match the experimental modal data of the free plates, just after they were CNC routed. This paper explains in detail this optimisation process and show the results for the six top and six back plates. The proposed approach enables the identification of material properties in multiple directions and ensures a step-by-step control of the accuracy of the modeled parts compared to the real ones.

Eley Nolan, Lavandier Catherine, Psychoyou Théodora et al.

A listening test was performed to determine whether there were any perceived differences in the playing styles of musicians as a function of the room in which the music was performed. This listening test was part of a larger study aimed at investigating the impact of room acoustics on historically informed performance (HIP) of baroque music which included an objective analysis framework designed to capture dimensions of performance important to a historical baroque playing style. The test included both flute and viol examples and included the participation of 20 musically trained listeners with a background in HIP. The results of the test showed some significant differences in certain performance parameters for both instruments. In particular, the flute examples demonstrated differences that aligned with reports from the flutists about the strategies they used to adapt to the different acoustics, and there was agreement between listener ratings and previously extracted objective parameters. These findings suggest that room acoustics play a role in shaping musical performance, and that the resulting changes can be perceived by listeners.

Vallely Sven, Schoenwald Stefan

Cross-Laminated Timber (CLT) is a wood composite that is popular due to its favourable stiffness-to-mass-density ratio and environmental benefits, among other positive attributes. This paper presents the estimation of higher-order modal parameters and their use in the verification and validation of an Equivalent Single-Layer (ESL) CLT model. The eigenvectors, eigenfrequencies, and modal damping ratios of 20 out-of-plane vibration modes were experimentally determined. The experimentally determined eigenfrequencies and eigenmodes were correlated and compared to those derived from a numerical model. The modal damping ratios were compared to damping loss factors derived from the power injection method. A broadband frequency view is also considered, with the comparison of experimental and numerical forced response models. As part of the verification and validation process, a framework of key indices and respective criteria is suggested and discussed in this contribution. Over the course of the paper, an ESL CLT model which derives its properties from a layerwise basis is validated in detail against experimental measurements. The results are intended to be of relevance to both structural and acoustic domains.

dos Santos Arthur, Pereira Jayr, Nogueira Rodrigo et al.

The increasing number of scientific publications in acoustics, in general, presents difficulties in conducting traditional literature surveys. This work explores the use of a generative pre-trained transformer (GPT) model to automate a literature survey of 117 articles on data-driven speech enhancement methods. The main objective is to evaluate the capabilities and limitations of the model in providing accurate responses to specific queries about the papers selected from a reference human-based survey. While we see great potential to automate literature surveys in acoustics, improvements are needed to address technical questions more clearly and accurately.

Dietze Anna, Reinsch Anna-Lena, Encke Jörg et al.

Identifying the causes underlying a person’s hearing impairment is challenging. It requires linking the results of listening tests to possible pathologies of the highly non-linear auditory system. This process is further aggravated by restrictions in measurement time, especially in clinical settings. A central but difficult goal is thus, to maximize the diagnostic information that is collectable within a given time frame. This study demonstrates the practical applicability of the model-based experiment-steering procedure introduced in Herrmann and Dietz (2021, Acta Acustica, 5:51). The approach chooses the stimuli that are presented and estimates the model parameters best predicting the subject’s performance using a maximum-likelihood method. The same binaural tone-in-noise detection task was conducted using two measurement procedures: A standard adaptive staircase procedure and the model-based selection procedure based on an existing model. The model-steered procedure reached the same accuracy of model parameter estimation in on average only 42% of the time that was required with the standard adaptive procedure. Difficulties regarding the choice of a reliable model and reasonable discretization steps of its parameters are discussed. Although the physiological causes of an individual’s results cannot directly be inferred using this procedure, a characterization in terms of functional parameters is possible.

Maria Cairoli

Vu Alex, Chakrapani Sunil Kishore

This article aims to study the interaction of Rayleigh or surface wave with a varying angled wedge using numerical simulations. This work uses numerical tools to understand this complex problem and fills some existing gaps such as the influence of frequency and geometry of the wedge (curved vs. sharp transition). Quantitative analysis was carried out by calculating the transmission and reflection coefficients, and qualitative analysis used displacement vector plots to study the scattering and mode conversion phenomenon. The results suggest a strong dependence of transmission and reflection coefficients on the frequency and geometry of transition, which has not been reported before in the literature.

Kiyan Roman, Bergner Jakob, Preihs Stephan et al.

When evaluating surround sound loudspeaker reproduction, perceptual effects are commonly analyzed in relationship to different loudspeaker configurations. The presented work contributes to this by modeling perceptual effects based on acoustic properties of various reproduction formats. A model of immersion in music listening is derived from the results of an experimental study analyzing the psychological construct of immersive music experience. The proposed approach is evaluated with respect to the relationship between immersion ratings and sound field features obtained from re-recordings of the stimuli using a spherical microphone array at the listening position. Spatial sound field parameters such as inter-aural cross-correlation (IACC), diffuseness and directivity are found to be of particular relevance. Further, immersion is observed to reach a point of saturation with greater numbers of loudspeakers, which is confirmed to be predictable from the physical properties of the sound field. Although effects related to participants and musical pieces outweigh the impact of sound field features, the proposed approach is found to be suitable for predicting population-average ratings, i.e. immersion experienced by an average listener for unknown content. The proposed method could complement existing research on multichannel loudspeaker reproduction by establishing a more generalizable framework independent of particular speaker setups.

Yang Jing, Barrett Jenna, Yin Zhigang et al.

This study examined how talker accentedness affects the recognition of noise-vocoded speech by native English listeners and how contextual information interplays with talker accentedness during this process. The listeners included 20 native English-speaking, normal-hearing adults aged between 19 and 23 years old. The stimuli were English Hearing in Noise Test (HINT) and Revised Speech Perception in Noise (R-SPIN) sentences produced by four native Mandarin talkers (two males and two females) who learned English as a second language. Two talkers (one in each sex) had a mild foreign accent and the other two had a moderate foreign accent. A six-channel noise vocoder was used to process the stimulus sentences. The vocoder-processed and unprocessed sentences were presented to the listeners. The results revealed that talkers’ foreign accents introduced additional detrimental effects besides spectral degradation and that the negative effect was exacerbated as the foreign accent became stronger. While the contextual information provided a beneficial role in recognizing mildly accented vocoded speech, the magnitude of contextual benefit decreased as the talkers’ accentedness increased. These findings revealed the joint influence of talker variability and sentence context on the perception of degraded speech.

Döllinger Michael, Zhang Zhaoyan, Schoder Stefan et al.

Numerical modeling of the human phonatory process has become more and more in focus during the last two decades. The increase in computational power and the use of high-performance computation (HPC) yielded more complex models being closer to the actual fluid-structure-acoustic interaction (FSAI) within the human phonatory process. However, several different simulation approaches with varying mathematical complexity and focus on certain parts of the phonatory process exist. Currently, models are suggested based on ordinary differential equations (reduced order models) but also on partial differential equations based on continuum mechanics as e.g. the Navier–Stokes equations for the flow discretized by Finite-Volume or Finite-Element-Methods. This review will illuminate current trends and recent progress within the area. In summary, the ultimate simulation model satisfying all physiological needs and scientific opinions still has to be developed.

Wang Xing, Hopkins Carl

Advanced Statistical Energy Analysis (ASEA) is used to predict vibrational response on a three-bay linear grillage of beams that supports multiple wave types when there is significant indirect coupling through tunneling mechanisms. For bending wave excitation where the component beams have identical material properties, there was agreement between measurements, ASEA and FEM (Finite Element Methods). The importance of indirect coupling was confirmed for bending-longitudinal and bending-torsional models due to ASEA predicting a higher response than SEA on beams that were distant from the source, and closer agreement between FEM and ASEA (rather than SEA) with only bending modes on all the beams or where beams supported longitudinal or torsional modes as well as bending modes. To investigate an imperfectly periodic, finite grillage that could exist due to engineering tolerances, numerical experiments with FEM were used to introduce uncertainty into the Young’s modulus for each beam. For beams modelled with Euler-Bernoulli or Timoshenko theory, the effect of this uncertainty was to reduce differences between FEM and ASEA to less than ≈3 dB. The results confirm the ability of ASEA to predict vibration transmission with significant indirect coupling across frameworks of beams that support local modes with multiple wave types.

Bouzid Islem, Côte Renaud, Fakhfakh Tahar et al.

This article presents a method for identifying the parameters of a simplified 2 degree of freedom model representative of a linear primary system coupled to a non-linear absorber in a forced harmonic regime over a wide range of amplitudes and forcing frequencies covering different dynamical regimes. This is a priori a difficult operation because it is necessary to combine two apparently contradictory steps. The first step consists in establishing models representing the physics of the system which are analytically soluble, which imposes severe approximations. The second step consists in adjusting the parameters of the models to experimental data, which reveal some phenomena ignored by the models. To do so, two approximate analytic methods, Harmonic Balance and Complexification Averaging under 1:1 resonance, are used to describe the dynamics of the nonlinear system for its different operating regimes: linear behavior, nonlinear behavior without energy pumping, energy pumping, and saturation regime. Then, using a non-linear regression, the parameters of the simplified model are identified from experiments. The values obtained correspond to the expected physical quantities.

van de Par Steven, Ewert Stephan D., Hladek Lubos et al.

While experimentation with synthetic stimuli in abstracted listening situations has a long standing and successful history in hearing research, an increased interest exists on closing the remaining gap towards real-life listening by replicating situations with high ecological validity in the lab. This is important for understanding the underlying auditory mechanisms and their relevance in real-life situations as well as for developing and evaluating increasingly sophisticated algorithms for hearing assistance. A range of ‘classical’ stimuli and paradigms have evolved to de-facto standards in psychoacoustics, which are simplistic and can be easily reproduced across laboratories. While they ideally allow for across laboratory comparisons and reproducible research, they, however, lack the acoustic stimulus complexity and the availability of visual information as observed in everyday life communication and listening situations. This contribution aims to provide and establish an extendable set of complex auditory-visual scenes for hearing research that allow for ecologically valid testing in realistic scenes while also supporting reproducibility and comparability of scientific results. Three virtual environments are provided (underground station, pub, living room), consisting of a detailed visual model, an acoustic geometry model with acoustic surface properties as well as a set of acoustic measurements in the respective real-world environments. The current data set enables i) audio–visual research in a reproducible set of environments, ii) comparison of room acoustic simulation methods with “ground truth” acoustic measurements, iii) a condensation point for future extensions and contributions for developments towards standardized test cases for ecologically valid hearing research in complex scenes.

Hejazi Nooghabi Aida, Grimal Quentin, Herrel Anthony et al.

We implement a new algorithm to model acoustic wave propagation through and around a dolphin skull, using the k-Wave software package [1]. The equation of motion is integrated numerically in a complex three-dimensional structure via a pseudospectral scheme which, importantly, accounts for lateral heterogeneities in the mechanical properties of bone. Modeling wave propagation in the skull of dolphins contributes to our understanding of how their sound localization and echolocation mechanisms work. Dolphins are known to be highly effective at localizing sound sources; in particular, they have been shown to be equally sensitive to changes in the elevation and azimuth of the sound source, while other studied species, e.g. humans, are much more sensitive to the latter than to the former. A laboratory experiment conducted by our team on a dry skull [2] has shown that sound reverberated in bones could possibly play an important role in enhancing localization accuracy, and it has been speculated that the dolphin sound localization system could somehow rely on the analysis of this information. We employ our new numerical model to simulate the response of the same skull used by [2] to sound sources at a wide and dense set of locations on the vertical plane. This work is the first step towards the implementation of a new tool for modeling source (echo)location in dolphins; in future work, this will allow us to effectively explore a wide variety of emitted signals and anatomical features.

Zacharakis Asterios, Pastiadis Konstantinos

Musically induced tension has been the subject of thorough study in the music cognition literature but its relationship with timbre is still poorly investigated. This study examines how the dynamic variation of a tone’s inharmonicity may affect a number of auditory qualities, namely brightness, roughness and mass along with felt tension under different acoustical conditions (i.e., F0, spectral shape and type of inharmonicity). Fifty-six musically trained participants gave real-time continuous ratings on eight time-varying stimuli upon the aforementioned qualities. Static ratings over the initial purely harmonic parts of the stimuli were also obtained by a subgroup of the listening panel. The fundamental frequency exhibits the strongest influence on the responses of the four qualities, followed by the type of inharmonicity and the spectral shape to a lesser degree. The profile patterns of mass and brightness proved to be strong predictors for tension profile patterns while the roughness profile magnitudes show a significant main effect on the magnitude of tension profiles. Overall, these results demonstrate that time-varying inharmonicity affects continuous responses on both timbral semantics and tension, while indicating that felt tension may be influenced by underlying timbral qualities in a dynamic context.

Edwards Matthew, Chevillotte Fabien, Bécot François-Xavier et al.