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Acoustics
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Vibration and Noise
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Vibration and Noise

A special issue of Acoustics (ISSN 2624-599X).

Deadline for manuscript submissions: closed (25 August 2023) | Viewed by 63237

Special Issue Editor

Dr. Yat Sze Choy

E-Mail Website
Guest Editor
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong
Interests: sound induced vibration; noise control; building acoustics; environmental noise measurement and control; sound sources identification
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nowadays, increasingly stringent regulations are coming into force, limiting the vibration and noise levels exposed to human beings and working environment. In this regard, the research on the control of vibration and noise is of growing importance. Therefore, this Special Issue of vibration and noise aims to include original research about the most recent advances in vibration and noise. The topics include, but are not limited to, the following: interaction of vibration and noise; vibrations caused by noise; radiation of noise from vibrating structures; control of low-frequency vibration and noise; the insulation and absorption of vibration and noise; theoretical, numerical, and experimental studies of vibration and noise; generation and propagation of vibration and noise; control of vibration and noise in aircraft, automobiles, machinery, and vehicles; materials for the control of vibration and noise. In addition, methods for the detection, measurement, and analysis of vibration and noise are within the scope of this Special Issue. As the topic of vibration and noise encompasses multidisciplinary areas, the coupling among structural vibration, noise, and fluid are also welcomed.

Dr. Yat Sze Choy
Guest Editor

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Keywords

  • noise control
  • noise generation
  • vibration control
  • vibration and Noise measurement and analysis
  • aircraft noise
  • automobile or vehicle noise
  • machinery noise
  • vibroacoustic coupling

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Related Special Issue

Published Papers (20 papers)

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Research

14 pages, 456 KiB  
Article
Using Feature Extraction to Perform Equipment Health Monitoring on Ship-Radiated Noise
by Nicholas Marasco, Haidy Elghamrawy and Donald McGaughey
Acoustics 2023, 5(4), 1180-1193; https://doi.org/10.3390/acoustics5040067 - 18 Dec 2023
Cited by 1 | Viewed by 2101
Abstract
The current state of the art in hydroacoustics research employs a variety of feature extraction techniques with the goal of accurately classifying a ship based on its radiated noise. These techniques are capable of accuracy in excess of 95%. A question arises as [...] Read more.
The current state of the art in hydroacoustics research employs a variety of feature extraction techniques with the goal of accurately classifying a ship based on its radiated noise. These techniques are capable of accuracy in excess of 95%. A question arises as to whether similar techniques could be applied to a known vessel to identify and monitor individual systems from the ship’s noise. In this paper, the fast orthogonal search algorithm is used as a basis for a feature extraction and classification algorithm. This algorithm is applied to real recordings of ship-radiated noise and is shown to be capable of identifying the running status of a subset of the ship’s systems, providing a proof of concept for the detection and monitoring of a ship’s systems based solely on the ships hydroacoustic noise. Full article
(This article belongs to the Special Issue Vibration and Noise)
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33 pages, 8555 KiB  
Article
Reducing Data Requirements for Simple and Effective Noise Mapping: A Case Study of Noise Mapping Using Computational Methods and GIS for the Raebareli City Intersection
by Md Iltaf Zafar, Shruti Bharadwaj, Rakesh Dubey, Saurabh Kr Tiwary and Susham Biswas
Acoustics 2023, 5(4), 1066-1098; https://doi.org/10.3390/acoustics5040061 - 14 Nov 2023
Cited by 1 | Viewed by 2279
Abstract
The accurate prediction of noise levels at outdoor locations requires detailed data of the noise sources and terrain parameters and an efficient model for prediction. However, the possibility of predicting noise with reasonable accuracy using less input data is a challenge and needs [...] Read more.
The accurate prediction of noise levels at outdoor locations requires detailed data of the noise sources and terrain parameters and an efficient model for prediction. However, the possibility of predicting noise with reasonable accuracy using less input data is a challenge and needs to be studied scientifically. The qualities of the noise data, terrain parameters, and prediction model can impact the accuracy of the prediction significantly. This study primarily focuses on the dependency of noise data for efficient noise prediction and mapping. This research article proposes a detailed methodology to predict and map the noise and exposure levels in Ratapur, Uttar Pradesh, India, with various granularities of noise data inputs. The noise levels were measured at various places and at different times of the day at 10 min intervals. Different data input proportions and qualities were used for noise prediction, namely, (1) a large data-based method, (2) a small data-based method, (3) a source point average data-based method, (4) a Google navigation data-based method, and (5) accurate modelling using an ANN-based method, integrating accurate noise data with a sophisticated modelling algorithm for noise prediction. The analysis of the variation between the predicted and measured noise levels was conducted for all five of the methods using the ANOVA technique. Various methods based on less noise data methods predicted the noise levels with accuracies within the ±4–10 dB(A) range, while the ANN-based technique predicted it with an accuracy of ±0.5–2.5 dB(A). Interestingly, the estimation of the noise exposure levels (>85 dB(A)) and the identification of hazard zones around the studied road intersection could also be performed efficiently even when using the data-deficient models. This paper also showcased the possibility of predicting an accurate 3D map for an area by extracting vehicles and terrain features from satellite images without any direct recording of noise data. This paper thus demonstrated approaches to reduce the noise data dependency for noise prediction and mapping and to enable accurate noise-hazard zonation mapping. Full article
(This article belongs to the Special Issue Vibration and Noise)
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12 pages, 4346 KiB  
Article
Sound Environment during Dental Treatment in Relation to COVID-19 Pandemic
by Tomomi Yamada, Kazunori Nozaki, Mikako Hayashi and Sonoko Kuwano
Acoustics 2023, 5(4), 987-998; https://doi.org/10.3390/acoustics5040056 - 26 Oct 2023
Cited by 1 | Viewed by 2309
Abstract
This study delves into the acoustic environment within dental clinics, particularly focusing on the impact of extraoral suction devices employed for infection control amid the COVID-19 pandemic. The research encompasses a comprehensive investigation, including a questionnaire survey of dental professionals, sound level measurements [...] Read more.
This study delves into the acoustic environment within dental clinics, particularly focusing on the impact of extraoral suction devices employed for infection control amid the COVID-19 pandemic. The research encompasses a comprehensive investigation, including a questionnaire survey of dental professionals, sound level measurements at suction device openings, acoustic imaging, and a detailed analysis of sound levels and their spectral characteristics during dental procedures. Additionally, ambient sound levels within clinical settings were monitored over two consecutive days. The findings reveal notable observations. Dental professionals expressed concerns regarding increased sound levels and associated distress caused by extraoral suction device operation. Objective measurements identified varying A-weighted sound pressure levels ranging from 86.0 dB to 96.7 dB at suction device openings, highlighting elevated sound pressure levels and a wide frequency range, especially in the vicinity of both the dentist and the patient’s facial area during dental aerosol procedures. On the other hand, for the entire clinical room, the equivalent continuous A-weighted sound pressure level during the consultation hours was not considered problematic. In light of these findings, it becomes evident that there is a pressing necessity to refine the acoustic characteristics of extraoral suction devices to foster a more accommodating acoustic environment for both patients and dental healthcare professionals within dental clinics. Full article
(This article belongs to the Special Issue Vibration and Noise)
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39 pages, 19134 KiB  
Article
On the Influence of Scattered Errors over Full-Field Receptances in the Rayleigh Integral Approximation of Sound Radiation from a Vibrating Plate
by Alessandro Zanarini
Acoustics 2023, 5(4), 948-986; https://doi.org/10.3390/acoustics5040055 - 24 Oct 2023
Cited by 5 | Viewed by 2578
Abstract
Spatially dense operative deflection shapes and receptances, acquired in broad frequency bands, increase the detail in the spatial and frequency domains of the responses of parts in actual dynamic loading, manufacturing and mounting conditions. This work remarks the potential benefits of greater [...] Read more.
Spatially dense operative deflection shapes and receptances, acquired in broad frequency bands, increase the detail in the spatial and frequency domains of the responses of parts in actual dynamic loading, manufacturing and mounting conditions. This work remarks the potential benefits of greater spatial resolution in the Rayleigh integral approximation of sound pressure—here reformulated to exploit the increased quality output from experiment-based optical full-field technologies in contactless structural dynamics—radiated by a vibrating surface in a broad frequency band. But in some cases the noise that is scattered over the estimated receptance maps might be heavier, or with different patterns, than expected, with potential repercussions on the sound pressure simulations that come thereof. This work covers this specific latter issue with insight over examples from experiment-based receptances of a lightweight vibrating plate. The effects of error spreading are analysed in the space and frequency domains, with special attention to the contribution of the experiment-based full-field receptance maps to the accuracy of the vibro-acoustic frequency response function maps. Full article
(This article belongs to the Special Issue Vibration and Noise)
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16 pages, 2486 KiB  
Article
Experimental Determination of the Masking Threshold for Tonal Powertrain Noise in Electric Vehicles
by Victor Abbink, David Landes and M. Ercan Altinsoy
Acoustics 2023, 5(4), 882-897; https://doi.org/10.3390/acoustics5040051 - 28 Sep 2023
Cited by 2 | Viewed by 2488
Abstract
Tonal powertrain noise can have a strong negative impact on vehicle sound quality. Therefore, an assessment of the perceptibility of tonal noise with respect to masking noise is essential for the vehicle development process. In electric vehicles, due to the missing masking by [...] Read more.
Tonal powertrain noise can have a strong negative impact on vehicle sound quality. Therefore, an assessment of the perceptibility of tonal noise with respect to masking noise is essential for the vehicle development process. In electric vehicles, due to the missing masking by the combustion engine, new methods are required for this purpose. In this study, listening tests were conducted to determine the masking threshold in the electric vehicle interior for various driving speeds (30 km/h, 60 km/h, and 90 km/h) with an Adaptive-Forced-Choice method. The novelty of this study is that it used vehicle interior noise as a masker, compared to broadband or narrowband white and pink noises. It could be shown that the masking threshold in electric vehicles strongly depends on the driving speed, and the investigated interior noise mainly affects frequencies up to 6400 Hz in this speed range. For frequencies greater than 6400 Hz, the masking noise has no significant effect on perceptibility of tonal noise in the investigated vehicle, and only the subjects’ individual absolute threshold of hearing is relevant. Additionally, a strong variation in the masking threshold between the subjects was found for high frequencies. With these results, methods that estimate masking thresholds in electric vehicles can be improved. Furthermore, threshold targets can be adjusted for different customer groups. Full article
(This article belongs to the Special Issue Vibration and Noise)
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10 pages, 233 KiB  
Article
Extending Soundwalking Practice: Soundsitting as an Inclusive and Complementary Method to Soundwalking
by Neil Spencer Bruce
Acoustics 2023, 5(3), 788-797; https://doi.org/10.3390/acoustics5030046 - 22 Aug 2023
Cited by 1 | Viewed by 2477
Abstract
This paper proposes the ‘soundsit’ as an alternative method to be used independently or in conjunction with current soundwalking methodological practice. The soundsit seeks to address the limits of the soundwalking method in relation to issues of transition, changing context, event [...] Read more.
This paper proposes the ‘soundsit’ as an alternative method to be used independently or in conjunction with current soundwalking methodological practice. The soundsit seeks to address the limits of the soundwalking method in relation to issues of transition, changing context, event occurrence, temporality, and inclusivity. Soundwalking and soundsitting are both methods of experiencing soundscape: soundwalking involves exploring and listening to the sounds of the environment while moving through it, while soundsitting involves sitting still in a particular place and listening to the sounds that exist in situ. The soundsit provides the participant or researcher with a fixed perspective and place to observe and experience sounds, within a defined soundscape context, enabling them to gain a longer-term experiential understanding of a space. Analogous with acoustic measurements, soundsitting is comparable to capturing average energy equivalent sound level LAeq measurements in allowing the perception of and activities within a soundscape to settle into a steady state. Beyond obtaining a longer-term impression of a chosen sound environment, soundsitting allows for a participant to disengage with the visual, which allows for deeper engagement and focus when listening to a soundscape; in addition, soundsitting removes the safety implications and distractions of walking practice and, as such, is a more inclusive form of activity, allowing those who are unable to walk to engage in the practice. The static nature of the listening experience allows for a different type of immersion through engaged active listening, something which is not possible on a soundwalk, allowing for deeper qualitative analysis and insight into the soundscape of a specific space or location. The primary findings show with test group of n = 6 that both methods are effective soundscape study tools, and further work with diverse groups is required. Full article
(This article belongs to the Special Issue Vibration and Noise)
19 pages, 4682 KiB  
Article
Key Factors That Influence the Frequency Range of Measured Leak Noise in Buried Plastic Water Pipes: Theory and Experiment
by Oscar Scussel, Michael J. Brennan, Fabrício Cézar L. de Almeida, Mauricio K. Iwanaga, Jennifer M. Muggleton, Phillip F. Joseph and Yan Gao
Acoustics 2023, 5(2), 490-508; https://doi.org/10.3390/acoustics5020029 - 12 May 2023
Cited by 4 | Viewed by 3736
Abstract
The frequency range of the leak noise in buried water pipes, measured using acoustic correlators, depends significantly on the type of pipe and its location as well as the type of sensors used. Having a rough idea of this frequency range can be [...] Read more.
The frequency range of the leak noise in buried water pipes, measured using acoustic correlators, depends significantly on the type of pipe and its location as well as the type of sensors used. Having a rough idea of this frequency range can be beneficial for operators prior to conducting tests; however, there is currently no method of predicting it except through practical experience, and no model-based approach yet exists. This issue is addressed in the present paper by using a concise and relatively simple analytical model of the water-pipe–soil system combined with the sensors’ frequency response. The influence of the various physical parameters of the system, such as the pipe and soil properties and the sensor type, on the cross-power spectral density (CPSD) of leak noise signals and, furthermore, the frequency range are investigated. The main factors that affect the bandwidth are the distance between the sensors, wave speed of the predominantly fluid-borne wave in the pipe and the attenuation of this wave. It is shown that the external medium has a profound effect on the propagation and, in turn, on the bandwidth. The approach to predicting this bandwidth is validated using experimental data from three different test sites. Full article
(This article belongs to the Special Issue Vibration and Noise)
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14 pages, 1250 KiB  
Article
Experimental Methodology to Characterize the Noise Paths in a Horizontal-Axis Washing Machine
by Cristian Albero and Beatriz Sánchez-Tabuenca
Acoustics 2023, 5(2), 476-489; https://doi.org/10.3390/acoustics5020028 - 9 May 2023
Viewed by 2678
Abstract
In this paper, an experimental methodology to characterize the noise paths in a washing machine with a horizontal axis was developed. The noise paths considered in this research were the noise that escapes through holes, the non-resonant path through the panels, and the [...] Read more.
In this paper, an experimental methodology to characterize the noise paths in a washing machine with a horizontal axis was developed. The noise paths considered in this research were the noise that escapes through holes, the non-resonant path through the panels, and the noise radiated by the panels of the cabinet. The characterization method was based on several sound intensity measurements on the outside panels of the washing machine. In addition to these measurements, characterization of the radiation factor was performed by applying a method that relates intensity and vibration measurements while the structure of the washing machine is excited using a shaker. Applying the methodology to a washing machine, the main transmission path of the noise along the frequency domain where this home appliance has its highest values was identified. This methodology can provide the manufacturer with a guide to improve the acoustic performance of washing machines by applying noise control solutions in the noise path depending on the frequency domain. Full article
(This article belongs to the Special Issue Vibration and Noise)
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13 pages, 2011 KiB  
Article
Diagnosis of Noise Inside Neonatal Incubators under Free-Field Conditions
by Francisco Fernández-Zacarías, Juan Luis Beira-Jiménez, Virginia Puyana-Romero and Ricardo Hernández-Molina
Acoustics 2023, 5(2), 354-366; https://doi.org/10.3390/acoustics5020021 - 26 Mar 2023
Cited by 2 | Viewed by 2691
Abstract
The study aims to diagnose the sound pressure levels inside incubators in a controlled environment under free-field conditions. The tests were carried out in a semi-anechoic room under the standard UNE-EN ISO 3745:2012/A1:2018 in three different operating states: off, on, and on with [...] Read more.
The study aims to diagnose the sound pressure levels inside incubators in a controlled environment under free-field conditions. The tests were carried out in a semi-anechoic room under the standard UNE-EN ISO 3745:2012/A1:2018 in three different operating states: off, on, and on with a temperature alarm triggered. Sound pressure levels were analyzed in three different models of incubators, both inside and outside. The main noise indices analyzed were the corrected equivalent continuous level (LKeq) and the equivalent continuous level (Leq) in third-octave bands. The results obtained under normal operating conditions showed variations among the different incubators, with overall values between 48.8 and 56.3 dBA. The influence of the alarm considerably worsened these data. The values obtained showed that premature newborns are exposed to noise levels above international recommendations. All incubators tested showed the presence of tonal components, both outside and inside the incubator cabin, and, in some cases, low-frequency components, but no impulsivity components were observed in any case. Full article
(This article belongs to the Special Issue Vibration and Noise)
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12 pages, 1744 KiB  
Article
Effects of Conventional and Musician-Specific Hearing Protection Devices on Speech Intelligibility
by Giovanna Cardoso Pinto, Clayton Henrique Rocha, Carla Gentile Matas and Alessandra Giannella Samelli
Acoustics 2023, 5(1), 242-253; https://doi.org/10.3390/acoustics5010014 - 27 Feb 2023
Viewed by 2440
Abstract
(1) Background: To assess and compare speech intelligibility with conventional and universal musician-specific hearing protection devices (HPD); (2) Methods: The sample comprised 15 normal-hearing musicians of both sexes who had been professionals for more than 5 years. They underwent thorough audiological assessment and [...] Read more.
(1) Background: To assess and compare speech intelligibility with conventional and universal musician-specific hearing protection devices (HPD); (2) Methods: The sample comprised 15 normal-hearing musicians of both sexes who had been professionals for more than 5 years. They underwent thorough audiological assessment and free-field audiometry to measure the attenuation levels of three HPD models (musician-specific, silicone, and foam devices). The sentence recognition thresholds in quiet (SRTQ) and noise (SRTN) were assessed with the Lists of Sentences in Portuguese. User satisfaction with musician HPD was assessed after 2 months; (3) Results: Conventional HPD had higher pure-tone mean attenuation levels than musician HPD. No statistically significant differences were found in SRTQ and SRTN between the three HPD types. However, the musician HPD had higher mean signal-to-noise ratios and percentages of correct words from sentences presented in noise than the other HPD. The answers also indicated a positive trend toward satisfaction with the musician-specific HPD; (4) Conclusions: Despite the lack of significant differences in speech intelligibility while wearing the three HPD models in either quiet or noise, the musician-specific HPD provided greater musical sound quality. This reinforces the possibility of an effective and adequate use of protection to preserve musicians’ hearing. Full article
(This article belongs to the Special Issue Vibration and Noise)
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12 pages, 6249 KiB  
Article
FEM-BEM Vibroacoustic Simulations of Motion Driven Cymbal-Drumstick Interactions
by Evaggelos Kaselouris, Stella Paschalidou, Chrisoula Alexandraki and Vasilis Dimitriou
Acoustics 2023, 5(1), 165-176; https://doi.org/10.3390/acoustics5010010 - 2 Feb 2023
Cited by 4 | Viewed by 3338
Abstract
The transient acoustic dynamics of a splash cymbal are investigated via the Finite Element Method-Boundary Element Method. Real three-dimensional motion data recorded from the interaction of drummer–drumstick–cymbal provide the initial and the loading conditions to the simulated interaction of the drumstick–cymbal Finite Element [...] Read more.
The transient acoustic dynamics of a splash cymbal are investigated via the Finite Element Method-Boundary Element Method. Real three-dimensional motion data recorded from the interaction of drummer–drumstick–cymbal provide the initial and the loading conditions to the simulated interaction of the drumstick–cymbal Finite Element Models. Progressively intensified free strokes are used as loading conditions for both experiment and simulation. The velocity values of the moving drumstick in various drumming conditions are monitored, recorded, and analysed to provide input data into the time domain simulations. The synergy of motion capturing and numerical methods allows computing the sound generated by the combined interaction of the vibroacoustic behaviour of the cymbal with the motor-interaction of the performer. The proposed methodology promotes a novel perspective in musical instrument design, optimization, and manufacturing considering performance discrepancies intentionally introduced by performers. Full article
(This article belongs to the Special Issue Vibration and Noise)
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33 pages, 9560 KiB  
Article
GIS Based Road Traffic Noise Mapping and Assessment of Health Hazards for a Developing Urban Intersection
by Md Iltaf Zafar, Rakesh Dubey, Shruti Bharadwaj, Alok Kumar, Karan Kumar Paswan, Anubhav Srivastava, Saurabh Kr Tiwary and Susham Biswas
Acoustics 2023, 5(1), 87-119; https://doi.org/10.3390/acoustics5010006 - 13 Jan 2023
Cited by 7 | Viewed by 5970
Abstract
Determination of health hazards of noise pollution is a challenge for any developing city intersection. The people working at roadside open-air shops or near the congested roads of any intersection face intense noise pollution. It becomes very difficult to efficiently determine the hazards [...] Read more.
Determination of health hazards of noise pollution is a challenge for any developing city intersection. The people working at roadside open-air shops or near the congested roads of any intersection face intense noise pollution. It becomes very difficult to efficiently determine the hazards of noise on the health of people living near the intersection. An attempt was made to determine the noise-induced health hazards of the developing city of Bahadurpur, UP, India. The noise levels were monitored over 17 station points of the intersection for three months at different times of the day. Equivalent noise level (Leq) maps were determined within an accuracy of ±4dB. Areas adjacent to intersections indicated noise exposure levels close to 100 dB. Health hazards for the people of the intersection were determined through the testing of auditory and non-auditory health parameters for 100 people. A total of 75–92% of the people who work/live near the noisy intersection were found to be suffering from hearing impairment, tinnitus, sleep disturbance, cardiovascular diseases, hypertension, etc. Whether the recorded health hazards were indeed related to noise exposure was confirmed by testing the health parameters of people from the nearby and less noisy area of Pure Ganga. The nearby site reported mild hazards to the health of the population. An alarming level of hearing impairment was prevalent in the noisy Bahadurpur intersection (79–95%) compared to the same in Pure Ganga (13–30%). The estimated noise-induced health hazards were also compared for noisy and less-noisy study sites using ANOVA statistics. The results suggested that the health hazards reported in the two sites are not similar. Further, the severe hazards to people’s health at the underdeveloped intersection were found to be primarily caused by the intense exposure to noise. Full article
(This article belongs to the Special Issue Vibration and Noise)
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15 pages, 16625 KiB  
Article
Study of Tire–Pavement Noise Acoustic Performance in Resilient Road Pavement Made of Strain-Hardening Cementitious Composites
by Ali Aryo Bawono, Nen NguyenDinh, Janaki Thangaraj, Maximilian Ertsey-Bayer, Christoph Simon, Bernhard Lechner, Stephan Freudenstein and En-Hua Yang
Acoustics 2023, 5(1), 57-71; https://doi.org/10.3390/acoustics5010004 - 9 Jan 2023
Viewed by 2643
Abstract
A modified strain-hardening cementitious composite (SHCC) material, fabricated using corundum aggregates (SHCC-Cor), has been proposed for roadway applications as it offers high structural performance and high skid resistance. However, the acoustic performance of SHCC is unclear and has not been well studied in [...] Read more.
A modified strain-hardening cementitious composite (SHCC) material, fabricated using corundum aggregates (SHCC-Cor), has been proposed for roadway applications as it offers high structural performance and high skid resistance. However, the acoustic performance of SHCC is unclear and has not been well studied in the past. Theoretically, SHCC may not provide the optimum solution in acoustic performance as it provides a low texture profile, high density, and low porosity. In this study, the acoustic performance of pavement slabs made of SHCC and modified SHCC-Cor are investigated using a nondestructive method to determine the surface roughness (macro texture) of slab surfaces. The pavement–tire noise level was then simulated using SPERoN software. As result, the noise level coming from the pavement made of SHCC could be up to 65 dB(A), while the noise level for SHCC-Cor increased up to 69.2 dB(A) because of the lower shape factor (G) due to a rougher surface as a result of the existence of corundum aggregate on the SHCC surface. The aeroacoustics were also increased compared to the SHCC slab. The modification of SHCC-Cor by introducing grooves (SHCC-Cor-Gro) successfully reduced the sound level coming from the vibration. Full article
(This article belongs to the Special Issue Vibration and Noise)
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11 pages, 2101 KiB  
Article
Investigation of the Change of Acoustic Pressure in an Element of Acoustic Barrier with an Elliptical Shape
by Krasimir Nedelchev, Elitsa Gieva, Ivan Kralov and Ivelina Ruskova
Acoustics 2023, 5(1), 46-56; https://doi.org/10.3390/acoustics5010003 - 31 Dec 2022
Cited by 1 | Viewed by 3015
Abstract
In the presented article we have investigated the variation of the sound pressure level in characteristic areas around an element of an acoustic barrier with an elliptical shape at different frequencies (from 100 Hz to 2000 Hz). The variation of the sound pressure [...] Read more.
In the presented article we have investigated the variation of the sound pressure level in characteristic areas around an element of an acoustic barrier with an elliptical shape at different frequencies (from 100 Hz to 2000 Hz). The variation of the sound pressure level in four characteristic areas located on the axis of symmetry of the acoustic barrier element is investigated. The purpose of the research is to determine in which of the areas it is most efficient to place devices for generating electrical energy from acoustic noise. The results were analyzed and relevant conclusions were drawn. Full article
(This article belongs to the Special Issue Vibration and Noise)
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27 pages, 5416 KiB  
Article
A Hybrid Multistep Procedure for the Vibroacoustic Simulation of Noise Emission from Wind Turbines
by Marc Zarnekow, Thomas Grätsch and Frank Ihlenburg
Acoustics 2023, 5(1), 1-27; https://doi.org/10.3390/acoustics5010001 - 22 Dec 2022
Viewed by 3166
Abstract
This paper proposes an efficient hybrid analytical-computational approach for the simulation of mechanical vibrations and sound radiation in wind turbine drive trains.The computational procedure encompasses the detailed modeling of vibrational sources and structural sound paths as well as the major panels of airborne [...] Read more.
This paper proposes an efficient hybrid analytical-computational approach for the simulation of mechanical vibrations and sound radiation in wind turbine drive trains.The computational procedure encompasses the detailed modeling of vibrational sources and structural sound paths as well as the major panels of airborne noise radiation. The angle-varying mesh stiffness is obtained from a series of quasi-static finite element simulations. A novel procedure is proposed to obtain the time-varying mesh stiffness at fluctuating speed. The varying mesh stiffness is introduced as a parametric excitation in an analytical gear model, and the Fourier-transformed results are used as vibrational sources in a finite-element-based harmonic response analysis of the drive train. The present paper focuses on the modeling of gear contact and gearbox vibrations. The models and procedures are outlined, and computational results are compared to physical measurements on a 2.5 MW wind turbine. The results are in good qualitative agreement at tonal frequencies. This is particularly the case at fluctuating speed, where both the simulation and the measurement show the characteristic effect of frequency modulation. The computational procedure has been expanded to the whole drive train and is effectively applied in the conception and evaluation of design measures for the reduction of tonal amplitudes. Full article
(This article belongs to the Special Issue Vibration and Noise)
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17 pages, 4915 KiB  
Article
A Modification of the Monte Carlo Filtering Approach for Correcting Negative SEA Loss Factors
by Paweł Nieradka and Andrzej Dobrucki
Acoustics 2022, 4(4), 1028-1044; https://doi.org/10.3390/acoustics4040063 - 16 Dec 2022
Cited by 1 | Viewed by 1893
Abstract
Monte Carlo Filtering (MCF) is one of the methods of Experimental Statistical Energy Analysis (E-SEA), which allows the correction of negative LFs (Loss Factors). In this article, a modification of the MCF method, called DESA (Diagonal Expansion of the Search Area), is proposed. [...] Read more.
Monte Carlo Filtering (MCF) is one of the methods of Experimental Statistical Energy Analysis (E-SEA), which allows the correction of negative LFs (Loss Factors). In this article, a modification of the MCF method, called DESA (Diagonal Expansion of the Search Area), is proposed. The technique applies a non-uniform extension of the search area when generating a population of normalized energy matrices. The degree of expansion of the search area is controlled by the Diagonal Penalty Factor (DPF). The authors demonstrated the method’s effectiveness on a system that could not be identified in several frequency bands by the classical MCF method. After applying DESA, it was possible to fill in the problematic bands that were missing CLF (coupling loss factor) and DLF (damping loss factor) values. The paper also proposes a way to minimize the errors introduced by using overly high DPF values. Full article
(This article belongs to the Special Issue Vibration and Noise)
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15 pages, 4160 KiB  
Article
Impact of Damping on Oscillation Patterns on the Plain Piano Soundboard
by Rolf Bader and Niko Plath
Acoustics 2022, 4(4), 1013-1027; https://doi.org/10.3390/acoustics4040062 - 2 Dec 2022
Cited by 1 | Viewed by 3142
Abstract
The influence of internal damping on the vibration of a piano soundboard is investigated using a Finite-Difference Time Domain (FDTD) physical model and experimental measurements. The damping constant of the model is varied according to a range similar to those found with measurements [...] Read more.
The influence of internal damping on the vibration of a piano soundboard is investigated using a Finite-Difference Time Domain (FDTD) physical model and experimental measurements. The damping constant of the model is varied according to a range similar to those found with measurements on a real grand piano at different production stages. With strong damping, a clear driving-point dependency of the forced string oscillation on the oscillation pattern of the soundboard is found. When decreasing the damping, this driving-point dependency is decreasing, nevertheless, it is still present. High damping, therefore, decreases soundboard vibration when strings drive the soundboard at the soundboard’s eigenfrequencies. However, such large damping increases soundboard vibrations when strings drive the soundboard at frequencies which are not eigenfrequencies. Therefore, strong damping smooths out the frequency response spectrum of an instrument. Extreme damping without any presence of distinct eigenmodes leads to a radiation of the strings sound spectrum without soundboard filtering. Low damping leads to a strong influence of the soundboard on the string’s radiated sound. Therefore, the amount of soundboard characteristics can be designed to alter internal damping process by choice of materials, including wood or varnish, and geometry. Additionally, damping reduces the presence of ’dead spots’, notes which are considerably lower in volume compared to other notes. Full article
(This article belongs to the Special Issue Vibration and Noise)
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14 pages, 4935 KiB  
Article
Correlation between Seismic Waves Velocity Changes and the Occurrence of Moderate Earthquakes at the Bending of the Eastern Carpathians (Vrancea)
by Anica-Otilia Placinta, Felix Borleanu, Iren-Adelina Moldovan and Alina Coman
Acoustics 2022, 4(4), 934-947; https://doi.org/10.3390/acoustics4040057 - 1 Nov 2022
Cited by 1 | Viewed by 3238
Abstract
Seismic velocity is the geophysical property that has a key role in characterizing dynamic processes and the state of the stress around the faults, providing valuable information regarding the change in the tectonic regime. The stress in the crust is an important indicator [...] Read more.
Seismic velocity is the geophysical property that has a key role in characterizing dynamic processes and the state of the stress around the faults, providing valuable information regarding the change in the tectonic regime. The stress in the crust is an important indicator of the possible occurrence of a major earthquake, and the variation of seismic velocities, in time, can provide a clearer picture on the tectonic processes taking place in the region. In the crust, velocities change before, during, and after earthquakes through several mechanisms related to fault deformations, pore pressure, stress changes, and recovery processes. In this study, we investigate the possible correlation between the changes of seismic velocities (Vp/Vs) in time and the occurrence of moderate size crustal and intermediate depth earthquakes from the Vrancea region. Our findings show that there are no significant variations in Vp/Vs for the intermediate depth earthquakes, while crustal events have decreased seismic activity prior to the main earthquake and no high Vp/Vs anomalies. Our results indicate key aspects, and such analyses should be carried out in real-time to continuously explore any unusual pattern pointed out by the seismic velocity changes. Vp/Vs and their standard errors can also be used to describe seismic activity patterns that shape the tectonic evolution of the area. Full article
(This article belongs to the Special Issue Vibration and Noise)
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19 pages, 7021 KiB  
Article
Flow Dynamics and Acoustics from Glottal Vibrations at Different Frequencies
by Jinxiang Xi, Mohamed Talaat, Xiuhua Si and Haibo Dong
Acoustics 2022, 4(4), 915-933; https://doi.org/10.3390/acoustics4040056 - 28 Oct 2022
Cited by 3 | Viewed by 2948
Abstract
Glottal vibration is fundamental to breathing-related disorders and respiratory sound generation. However, responses of the flow and acoustics to glottal vibrations of different frequencies are unclear. The objective of this study is to numerically evaluate the influences of glottal vibration frequencies on inspiratory [...] Read more.
Glottal vibration is fundamental to breathing-related disorders and respiratory sound generation. However, responses of the flow and acoustics to glottal vibrations of different frequencies are unclear. The objective of this study is to numerically evaluate the influences of glottal vibration frequencies on inspiratory airflow dynamics and flow-induced sound signals; this is different from normal phonation that is driven by controlled expiratory flows. A computational model was developed that comprised an image-based mouth–throat–lung model and a dynamic glottis expanding/contracting following a sinusoidal waveform. Large Eddy simulations were used to solve the temporal and spatial flow evolutions, and pressure signals were analyzed using different transform algorithms (wavelet, Hilbert, Fourier, etc.). Results show that glottal vibrations significantly altered the flows in the glottis and trachea, especially at high frequencies. With increasing vibration frequencies, the vortices decreased in scale and moved from the main flow to the walls. Phase shifts occurred between the glottis motion and glottal flow rates for all frequencies considered. Due to this phase shift, the pressure forces resisted the glottal motion in the first half of contraction/expansion and assisted the glottal motion in the second half of contraction/expansion. The magnitude of the glottal flow fluctuation was approximately linear with the vibration frequency (~f0), while the normal pressure force increased nonlinearly with the frequency (~f01.85). Instantaneous pressure signals were irregular at low vibration frequencies (10 and 20 Hz) but became more regular with increasing frequencies in the pressure profile, periodicity, and wavelet-transformed parameters. The acoustic characteristics specific to the glottal vibration frequency were explored in temporal and frequency domains, which may be used individually or as a combination in diagnosing vocal fold dysfunction, snoring, sleep apnea, or other breathing-related diseases. Full article
(This article belongs to the Special Issue Vibration and Noise)
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18 pages, 1183 KiB  
Article
A Time-Domain Finite-Difference Method for Bending Waves on Infinite Beams on an Elastic Foundation
by Katja Stampka and Ennes Sarradj
Acoustics 2022, 4(4), 867-884; https://doi.org/10.3390/acoustics4040052 - 5 Oct 2022
Cited by 1 | Viewed by 3061
Abstract
To model the vibration and structure-borne sound excitation and propagation of a railway rail, it can be modeled as an infinite beam on an elastic foundation. Existing analytical or numerical models are either formulated in the frequency domain or consider only finite beams [...] Read more.
To model the vibration and structure-borne sound excitation and propagation of a railway rail, it can be modeled as an infinite beam on an elastic foundation. Existing analytical or numerical models are either formulated in the frequency domain or consider only finite beams in the time domain. Therefore, a time-domain approach for bending wave propagation on an effectively infinite beam on an elastic foundation is proposed. The approach makes use of an implicit finite-difference method that allows for varying properties of the beam and the foundation along the length of the beam. Strategies for an efficient discretization are discussed. The method is validated against existing analytical models for a single layer and two layers, as well as continuous and discrete support. The results show very good agreement, and it can be concluded that the proposed method can be seen as a versatile method for simulating the behavior of a beam on different kinds of elastic foundations. Full article
(This article belongs to the Special Issue Vibration and Noise)
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