5th Anniversary of Acoustics and Vibrations Section—Recent Advances in Acoustics and Vibration

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 18217

Special Issue Editor


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Guest Editor
Department of Architecture, University of Bologna, 40126 Bologna, Italy
Interests: acoustics; room acoustics; musical acoustics; emulation of nonlinear acoustic systems; 3D auralisation; multiple arrays in 3D acoustic measurements; noise barriers
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Special Issue Information

Dear Collegues,

Acoustics and vibration represent fundamental aspects in all applied sciences, with an increasing impact on all of the applications in the industrialised world. Starting from the environmental aspects of noise and vibration pollution, moving to underwater acoustics, architectural and musical acoustics, acoustics and vibrations are widely considered and studied for different (and far) scientific fields, which include architecture, engineering, environmental sciences, but also medicine, food industry, cultural heritage, and also (recently) space technologies, In other words, an interdisciplinary approach.

These two interlaced topics have been studied and communicated to the scientific community of Applied Sciences since 2016, including measurements, modelling, simulations, in a wide range of different applications.

This Special Issue celebrates the 5th year of activity of this Section in Applied Sciences. With more than 1100 scientific articles already published, this Section has covered all the aforementioned areas of acoustics and vibration, authored by the most relevant scientists worldwide.  

Authors are invited to submit their work related to the following topics (but not limited to them):

§  Linear and non-linear acoustics;
  • Atmospheric, ultrasonics acoustics and aeroacoustics;
  • Measurements methods;
  • Structural acoustics and vibration;
  • Noise and environmental acoustics;
  • Architectural acoustics;
  • Building acoustics;
  • Psychoacoustics;
  • Speech and classroom acoustics;
  • Musical acoustics;
  • Underwater and animal acoustics;
  • Computational methods in acoustics.

Prof. Dr. Lamberto Tronchin
Guest Editor

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Published Papers (11 papers)

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Research

16 pages, 5296 KiB  
Article
Acoustic Characterization and Quality Assessment of Cremona’s Ponchielli Theater
by Lamberto Tronchin, Antonella Bevilacqua and Ruoran Yan
Appl. Sci. 2023, 13(6), 4057; https://doi.org/10.3390/app13064057 - 22 Mar 2023
Cited by 15 | Viewed by 998
Abstract
The Ponchielli theater of Cremona was built in 1808 after a fire destroyed the old wooden structure. The interior, the architecture and the shape of the plan layout are reminiscent of the Teatro alla Scala, Milan, a masterpiece by the architect Piermarini, albeit [...] Read more.
The Ponchielli theater of Cremona was built in 1808 after a fire destroyed the old wooden structure. The interior, the architecture and the shape of the plan layout are reminiscent of the Teatro alla Scala, Milan, a masterpiece by the architect Piermarini, albeit on a smaller scale. The four orders of balconies crowned by the top gallery are typical features of a 19th Century Italian Opera theater. Acoustic measurements have been undertaken across the stalls and in some selected boxes according to ISO 3382. The main acoustic parameters resulting from the measurements have been used for the acoustic calibration of a 3D model representing the Ponchielli theater. The calibration has been used to compare different scenarios involving the acoustic response of the main hall at 50% and 100% occupancy. The outcomes indicate that no significant change can be detected when the seats are provided with robust upholstery, which can be considered a positive result, especially for the actors who are not forced to change their effort between rehearsal and live performance. In order to contextualize the measured values in relation to the optimal ones, a comparison with other Italian Opera theaters provided with similar architectural characteristics has been carried out. Overall, the findings indicate that the acoustics of the Ponchielli theater are suitable for both music and speech in line with the other selected theaters, as these places were mainly created for multifunctional purposes in the 19th Century. Full article
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13 pages, 6034 KiB  
Article
The Only Architectural Testimony of an 18th Century Italian Gordonia-Style Miniature Theatre: An Acoustic Survey of the Monte Castello di Vibio Theatre
by Lamberto Tronchin, Ruoran Yan and Antonella Bevilacqua
Appl. Sci. 2023, 13(4), 2210; https://doi.org/10.3390/app13042210 - 09 Feb 2023
Cited by 15 | Viewed by 1012
Abstract
The acoustic characteristics and spatial features of the world’s only surviving Italianate Gordonia-style miniature theatre, one of the smallest theatres in the world, have inspired the author to analyse the acoustic behaviour of the Monte Castello di Vibio theatre, also called “Teatro della [...] Read more.
The acoustic characteristics and spatial features of the world’s only surviving Italianate Gordonia-style miniature theatre, one of the smallest theatres in the world, have inspired the author to analyse the acoustic behaviour of the Monte Castello di Vibio theatre, also called “Teatro della Concordia”. In this paper, the geometric and architectural features of this historical and unique performing art space were first reproduced, considering that these features are essential factors affecting acoustic characteristics. Subsequently, the acoustic measurements were taken throughout the stall and inside some selected boxes, and their main parameters were acoustically characterised according to ISO 3382-1. Lastly, the main acoustic parameters of the Monte Castello di Vibio theatre were compared to those of the 1763 theatre in Bologna, which is also a miniature theatre of similar size. The aim is to explore the main influences on the acoustic parameters of miniature theatres, and the results show that the plan layout of the theatre and interior decoration are the main factors influencing the acoustic characteristics rather than volume. Preserving the acoustic features of this unique heritage building is also seen as one of the goals of this paper. Full article
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12 pages, 5431 KiB  
Article
One Novel Dynamic-Load Time-Domain-Identification Method Based on Function Principle
by Hongqiu Li, Jinhui Jiang, Wenxu Cui, Jiamin Zhao and M. Shadi Mohamed
Appl. Sci. 2022, 12(19), 9623; https://doi.org/10.3390/app12199623 - 25 Sep 2022
Cited by 1 | Viewed by 1073
Abstract
In order to ensure the reliability of the structural design, it is necessary to know the external loads acting on the structure. In this paper, we propose a novel method to identify the dynamic loads based on function principles in the time domain. [...] Read more.
In order to ensure the reliability of the structural design, it is necessary to know the external loads acting on the structure. In this paper, we propose a novel method to identify the dynamic loads based on function principles in the time domain. Assuming the external load remains constant within one micro segment, we establish a linear relationship between external load and structural response in the micro segments based on the mechanical energy conservation law. Next, the external load is obtained by solving the inverse problem in each micro-segment. Finally, the external load in the whole time domain is achieved by fitting the load-identification results in each micro segment. In order to verify the effectiveness and accuracy, single-force and two-force identification, and load identification with noise simulations, are performed on the structures, and the identification results are compared to the ones of the traditional time-domain method with a deviation of less than 5%. The proposed method can effectively solve the problem of cumulative errors in the time-domain method, while its resistance to noise interference is also strong. At last, we verify the experimental performance of the proposed method. The experimental results show the effectiveness and high accuracy of the proposed method. This work presents a first attempt to solve the structural dynamic load with an approach based on a function principle. Full article
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19 pages, 5868 KiB  
Article
Structural Dynamic Model Updating with Automatic Mode Identification Using Particle Swarm Optimization
by Kaiyang Li, Jie Fang, Bing Sun, Yi Li and Guobiao Cai
Appl. Sci. 2022, 12(18), 8958; https://doi.org/10.3390/app12188958 - 06 Sep 2022
Viewed by 1123
Abstract
Dynamic model-updating methods are a useful tool for obtaining high-precision finite element (FE) models. However, when using such methods to update a model, there will be problems with incompleteness and mode switching. To overcome these problems, this paper proposes a structural dynamic model-updating [...] Read more.
Dynamic model-updating methods are a useful tool for obtaining high-precision finite element (FE) models. However, when using such methods to update a model, there will be problems with incompleteness and mode switching. To overcome these problems, this paper proposes a structural dynamic model-updating with an automatic mode-identification method. In this method, a mode-identification index is established based on image-similarity recognition to identify the consistency between FE and experimental mode shapes, and particle swarm optimization is introduced to update the model. In addition, to reduce the computational time, Latin hypercube sampling is employed to perform probability statistics of the switching range of the concerned mode orders, and the orders of mode identification are reduced according to the statistics results. In this paper, the proposed method was validated by model-updating of a square plate. The natural frequencies and mode shapes of the plate were obtained by experimental modal analysis and used as the updating objectives of the FE model. In addition, the boundary condition of the plate was simplified by a series of springs, which were used as updating parameters along with material properties and dimensions. Finally, the FE model of the plate was updated by the present method, and the results indicate that the objective function error of the updated FE model was successfully reduced from 14.31% to 1.05%, which proves that the proposed model-updating method is effective and feasible. Full article
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19 pages, 10958 KiB  
Article
Analytical Investigation of Sound Radiation from Functionally Graded Thin Plates Based on Elemental Radiator Approach and Physical Neutral Surface
by Baij Nath Singh, R. N. Hota, Sarvagya Dwivedi, Ratneshwar Jha, Vinayak Ranjan and Kamil Řehák
Appl. Sci. 2022, 12(15), 7707; https://doi.org/10.3390/app12157707 - 31 Jul 2022
Cited by 1 | Viewed by 1430
Abstract
This paper analyzes the sound radiation behavior of a clamped thin, functionally graded material plate using the classical plate theory and Rayleigh Integral with the elemental radiator approach. The material properties of the plate are assumed to vary according to the power-law distribution [...] Read more.
This paper analyzes the sound radiation behavior of a clamped thin, functionally graded material plate using the classical plate theory and Rayleigh Integral with the elemental radiator approach. The material properties of the plate are assumed to vary according to the power-law distribution of the constituent materials in the transverse direction. The functionally graded material is modeled using a physical neutral surface instead of a geometric middle surface. The effects of the power-law index, elastic modulus ratio, different constituent materials, and damping loss factor on the sound radiation of functionally graded plate are analyzed. It was found that, for the considered plate, the power-law index significantly influences sound power level and radiation efficiency. There exists a critical value of the power-law index for which the corresponding peak of sound power level is minimum. In a wide operating frequency range, approximately 500–1500 Hz, this research suggests that the radiation efficiency is lower for the power-law index equal to 0 and 1. However, for very low frequencies (less than 250 Hz), the power-law index does not affect radiation efficiency significantly. Further, as the modulus ratio increases, the sound power peak decreases for a given power-law index. For the given material constituents of the functionally graded plate, the different values of damping loss factors do not significantly influence radiation efficiency. However, the selection of material constituents affects the radiation efficiency peak. Full article
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14 pages, 52626 KiB  
Article
How Much Does the Variety of Scenery and the Different Percentages of Audience Occupancy Affect the Indoor Acoustics at the National Theater of Zagreb?
by Lamberto Tronchin and Antonella Bevilacqua
Appl. Sci. 2022, 12(13), 6500; https://doi.org/10.3390/app12136500 - 27 Jun 2022
Cited by 15 | Viewed by 1155
Abstract
The performance of opera and the post-pandemic slow recovery of the public, who have been hesitant to return to frequent attendance of cultural venues, has inspired the authors to analyze the acoustic behavior of the National Theater of Zagreb, by reflecting five specific [...] Read more.
The performance of opera and the post-pandemic slow recovery of the public, who have been hesitant to return to frequent attendance of cultural venues, has inspired the authors to analyze the acoustic behavior of the National Theater of Zagreb, by reflecting five specific scenarios. Starting from acoustic measurements undertaken inside the National Theater of Zagreb without any scenery in place, this research study compares the main acoustic parameters simulated with the scenery of Tosca in three different acts. A numerical model was realized by reproducing the geometry and the architectural features of this historic performance arts space. Before the simulations, the absorption coefficients applied to the digital entities were calibrated with the values gathered from the recorded impulse responses. After the calibration process, the acoustic simulations were also carried out with the presence of an audience at two percentages of occupancy. Full article
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17 pages, 2270 KiB  
Article
Analysis of the Effects and Causes of Driver Horn Use on the Acoustic Environment at Urban Intersections in Taiwan
by Masayuki Takada, Shoki Tsunekawa, Kazuma Hashimoto, Tamaki Inada, Ki-Hong Kim, Yoshinao Oeda, Katsuya Yamauchi and Shin-ichiro Iwamiya
Appl. Sci. 2022, 12(12), 5917; https://doi.org/10.3390/app12125917 - 10 Jun 2022
Cited by 1 | Viewed by 2338
Abstract
Car horns were originally installed in vehicles for safety. However, many urban areas in several countries face noise problems related to the use of car and motorbike horns. To propose measures to suppress the use of horns, relationships between horn use and factors [...] Read more.
Car horns were originally installed in vehicles for safety. However, many urban areas in several countries face noise problems related to the use of car and motorbike horns. To propose measures to suppress the use of horns, relationships between horn use and factors including driver awareness and behavior, traffic environment, and the transportation system should be investigated. The present study therefore conducted surveys to grasp the current circumstances of horn use and traffic at urban intersections in Taiwan. The relationship between horn use and the traffic volume of standard-sized vehicles was found. According to an analysis of horn use during traffic signal cycles, in many cases, horns were honked after entering intersections to turn left. In particular, horns were honked when the driver waited more than 4 s for the car in front to start moving after the green light allowing left turns was turned on. An analysis of noise levels at intersections showed that the maximum noise level value (LAmax) could be reduced if vehicle horns were not used. Multiple regression analysis also indicated that LAmax values increased with the frequency of horn use. The equivalent continuous A-weighted sound pressure level (LAeq,10min) did not change with driver horn use, and increased with the traffic volume of motorcycles. Full article
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13 pages, 2557 KiB  
Article
Experimental Analysis of Transformer Core Vibration and Noise under Inter-Harmonic Excitation
by Qiang He, Chao Fan, Guang Yang, Huiqi Li, Jiadong Li and Xiaogang Chen
Appl. Sci. 2022, 12(3), 1758; https://doi.org/10.3390/app12031758 - 08 Feb 2022
Cited by 3 | Viewed by 1916
Abstract
With the wide application of power electronic devices and nonlinear loads, the resulting inter-harmonic pollution is becoming more and more serious in the power system. As important equipment in power systems, transformers have always been the focus of research. However, there are few [...] Read more.
With the wide application of power electronic devices and nonlinear loads, the resulting inter-harmonic pollution is becoming more and more serious in the power system. As important equipment in power systems, transformers have always been the focus of research. However, there are few studies on the abnormal increase in vibration and noise caused by inter-harmonic excitation. In this work, a transformer core vibration and noise measurement platform that can generate arbitrary inter-harmonic excitations was built. The real-time vibration displacement waveforms of the core model under normal and inter-harmonic conditions were experimentally measured as well as the surrounding noise level amplitude and spectrum analysis result. The influence law of excitation of intermediate harmonic content and frequency on core vibration displacement and surrounding sound pressure level was summarized. The work of this paper lays a theoretical foundation for studying the vibration and noise of power transformers and other equipment under inter-harmonics. Full article
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17 pages, 1867 KiB  
Article
Application of a Musical Robot for Adjusting Guitar String Re-Excitation Parameters in Sound Synthesis
by Marek Janusz Pluta, Daniel Tokarczyk and Jerzy Wiciak
Appl. Sci. 2022, 12(3), 1659; https://doi.org/10.3390/app12031659 - 05 Feb 2022
Cited by 2 | Viewed by 1403
Abstract
Sound synthesis methods based on physical modelling of acoustic instruments depend on data that require measurements and recordings. If a musical instrument is operated by a human, a difficulty in filtering out variability is introduced due to a lack of repeatability in excitation [...] Read more.
Sound synthesis methods based on physical modelling of acoustic instruments depend on data that require measurements and recordings. If a musical instrument is operated by a human, a difficulty in filtering out variability is introduced due to a lack of repeatability in excitation parameters, or in varying physical contact between a musician and an instrument, resulting in the damping of vibrating elements. Musical robots can solve this problem. Their repeatability and controllability allows studying even subtle phenomena. This paper presents an application of a robot in studying the re-excitation of a string in an acoustic guitar. The obtained results are used to improve a simple synthesis model of a vibrating string, based on the finite difference method. The improved model reproduced the observed phenomena, such as the alteration of the signal spectrum, damping, and ringing, all of which can be perceived by a human, and add up to the final sound of an instrument. Moreover, as it was demonstrated by using two different string plucking mechanisms, musical robots can be redesigned to study other sound production phenomena and, thus, to further improve the behaviours of and sounds produced by models applied in sound synthesis. Full article
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7 pages, 9418 KiB  
Communication
Diffraction Effects of IEC63034 Standard Micro-Baffle on the Frequency Response Measurements of Microspeakers
by Jie Huang, Jun Gu, Xuelei Feng and Yong Shen
Appl. Sci. 2022, 12(3), 1420; https://doi.org/10.3390/app12031420 - 28 Jan 2022
Cited by 1 | Viewed by 1503
Abstract
This study investigates the diffraction effects of the IEC 63034 standard micro–baffle (SMB) on the frequency response (FR) measurements of microspeakers based on the extended Biot–Tolstoy–Medwin technique. Two different cases with and without the consideration of the backward diffractions of the SMB were [...] Read more.
This study investigates the diffraction effects of the IEC 63034 standard micro–baffle (SMB) on the frequency response (FR) measurements of microspeakers based on the extended Biot–Tolstoy–Medwin technique. Two different cases with and without the consideration of the backward diffractions of the SMB were investigated, which correspond to different practical measurement conditions of microspeaker drivers and closed-box microspeaker modules. The experimental results obtained were consistent with the theoretical analysis and numerical calculations. Normalized FR curves characterizing the SMB diffraction effects were presented, which can be used to compensate the FRs measured on the SMB to obtain the results measured on an ideal infinite baffle and eliminate the SMB diffraction effects. Full article
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15 pages, 6205 KiB  
Article
Impact Noise and Vibration Sources Induced by Heavy Gym Activities: Do They in Turn Unnecessarily, Indirectly Affect Our Health?
by Sakdirat Kaewunruen and Yu Shi
Appl. Sci. 2021, 11(24), 11812; https://doi.org/10.3390/app112411812 - 12 Dec 2021
Cited by 2 | Viewed by 2516
Abstract
‘Good health and wellbeing’ is one of the key United Nations sustainable development goals (SDGs). By ensuring healthy lives and promoting positive wellbeing, physical and mental activities have been encouraged for all at all ages. In recent decades, fitness culture and industry has [...] Read more.
‘Good health and wellbeing’ is one of the key United Nations sustainable development goals (SDGs). By ensuring healthy lives and promoting positive wellbeing, physical and mental activities have been encouraged for all at all ages. In recent decades, fitness culture and industry has significantly grown in many countries to enhance healthy lives and positive wellbeing. With the vigorous development of the fitness industry, a gym has become one of the common facilities within a neighborhood or on a campus in order to promote more and more people to participate in fitness activities. At the same time, the rapid increase in gym construction also provides more employment opportunities for professional fitness coaches. On the other hand, excessive noises and vibrations stemming from certain heavy gym activities can be observed. Accordingly, the NIHL (noise-induced hearing loss) in a gym should receive more attention. According to critical literature reviews, the high-intensity noise in gyms is mainly caused by the drops of heavy steel bars or dumbbells. Today, most gyms adopt cushioned flooring in specific areas, but the effectiveness of noise suppression still needs to be evaluated. The purpose of this study was to investigate the possibility of hearing loss caused by noise doses in a gym. Noises derived from heavy gym sources (i.e., lifting of heavy weights) were monitored and collected for analyses in order to estimate the risk of NIHL in a traditional gym, as well as to assess the measurements against the authoritative criteria to derive some technical guidelines for fitness and gym managers. The outcome of this study will improve insights into acoustic monitoring techniques and practical management within a gym environment. Full article
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