bluuebunny/crossref_metadata_2025 huggingface dataset:
Heavy Metal Pollution Assessment in the Agricultural Soils of Bonao, Dominican Republic
Authors: Alberto Then Natividad Miledy , Delanoy Ramón , Rodríguez Alberto Diana , Méndez Henández Ronaldo , Díaz Rizo Oscar , Bello Lizaira
Published: December 2023

Heavy metal content in agricultural soils potentially impacts the food chain and human health. The present study assessed the levels of heavy metals in topsoil samples collected within an agricultural region situated in Bonao, Dominican Republic. The Energy-Dispersive X-ray Fluorescence (EDXRF) technique was utilized to measure the concentrations of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), and arsenic (As) in the samples. The assessment of soil pollution status and potential ecological risk (RI) involved the utilization of various soil pollution indices, such as the single pollution index (PI), integrated pollution index (IPI), and enrichment factor (EF). The average total concentrations of Fe, Mn, Cr, Cu, Ni, Zn, Pb, and As were 103,000, 2000, 347, 36, 92, 32, 9.6, and 4.2 mg·kg−1, respectively. The results showed that the Mn, Ni, Cu, and As levels exceeded the Food and Agriculture Organization (FAO)’s recommended levels for healthy agricultural soils. The distribution pattern of each individual metal was different, indicating they had different sources of origin. The average pollution indices indicated low-to-moderate pollution, and the potential ecological risk obtained was low. This study emphasizes the need for soil management practices to mitigate heavy metal contamination for food safety and environmental health.
Increase of trailing-edge noise due to inflow turbulence
Authors: Botero-Bolívar Laura , dos Santos Fernanda L. , Venner Cornelis H. , de Santana Leandro D.
Published: December 2023

Altough the regulatory imposition of low-noise limits, airframe noise currently limits the design space of several applications, such as, wind energy, marine, and aeronautics. The noise of those applications is significantly increased by the presence of inflow turbulence. It has been
believed that only the leading-edge component is increased. However, recent results show that the trailing-edge noise is also increased because of the free-stream turbulence penetration in the airfoil boundary layer. This research measures the increase of trailing-edge noise due to inflow
turbulence for NACA 63018 and NACA 0008 airfoils. Noise measurements were conducted for velocities ranging from 15 to 40 m/s, with and without inflow turbulence. A rod installed upstream of the airfoils generated an inflow turbulence of ≈ 12%. The wall-pressure fluctuations were measured
close to the trailing edge to analyze the near-field phenomenon. The inflow turbulence increases the wall-pressure spectrum level in the entire frequency range and the spanwise correlation length in the low-frequency range. The trailing-edge noise increases due to the inflow turbulence in
the entire frequency range at least 2 db up to more than 15 dB for all the cases. The contribution of leading- and trailing-edge noise to the total noise varies with the airfoil geometry, with the trailing-edge noise dominating in a larger frequency range for the thickest airfoil.
Analysis of the short-term noise situation around Bangkok International Airport prior to the second phase of airport expansion begins
Authors: Lertsawat Krittika , Pimpin Alongkorn , Huntrakool Pornnapas , Sonjai Worasai
Published: December 2023

Short-term noise measurements carried out around the Bangkok International Airport during 2014-2015 provided baseline datasets of noise levels to illustrate the overview of actual aircraft noise exposure to people living underneath the flight path. The datasets will be useful for social
surveys to draw the dose-response relationship curve, validation of noise prediction studies, and noise management plans around the airport before the second phase expansion. This study proposes a post-processing tool for extracting aircraft noise events due to aircraft flyovers from the measurements.
The actual noise exposure levels of aircraft fly-over noise events were reported to reflect the existing noise situation around the airport and contribute to the analysis of other studies conducted during the same period.
A lightweight and transparent acoustic metamaterial sheet with designed structures for sound insulation applications
Authors: Nakayama Masanari , Matsuoka Takeshi , Saito Yuya , Uchida Naoyuki , Komamura Takahiro , Koshitouge Haruki , Akasaka Shuichi , Koga Shogo
Published: December 2023

Normal sound insulation materials such as metal plates and rubber sheets follow the mass law. According to the mass law, a weight increase of sound insulators leads to high sound insulation. Therefore, novel lightweight and high-performance materials have been required in various fields
such as mobility and electronics. We developed lightweight and transparent acoustic metamaterial sheets having blocklike weights with rodlike or cylindrical shapes periodically arranged on thin films. Upon sound incidence at a target frequency, the heavier weights and the lighter film cooperatively
vibrate in opposite phase and with the same amplitude. The transmitted sound waves through those parts cancel each other out owing to the wave interference. As a result, the acoustic metamaterial sheets show high sound insulation performance beyond the mass law limit at the target frequencies.
In this study, we report the structural design, sound insulation properties and mechanisms, and application of acoustic metamaterial sheets.
Global optimization of underwater vehicle hull shape on flow resistance
Authors: PENG RENHUA , JIN ZHONGKUN , BAI GUOFENG
Published: December 2023

For underwater vehicle with axisymmetric revolution body, the hull shape in the rotation axis section is the key issue on flow resistance. In this paper, we propose to use the elliptic Fourier descriptors for arbitrary hull shape modeling. By doing so, we can achieve global optimization
of underwater vehicle hull shape on flow resistance. Experimental results using the computational fluid dynamics show superior improvement compared to the extensive used Myring shape with only first order elliptic Fourier descriptors under the same displacement constraint. In addition, the
proposed method can be easily extend to the global optimization on flow noise.
An experimental investigation of ground board mounted microphones for outdoor noise measurement
Authors: Kingan Michael J. , Go Sung Tyaek , Hall Andrew , Schmid Gian
Published: December 2023

This paper reports an experimental investigation on the use of ground board mounted microphones for making outdoor noise measurements. The experiments utilized a 400 mm diameter thin metal ground board into which a probe microphone was flush mounted at a number of different radii. The
ground board was placed on the floor of an anechoic chamber and the noise level from a source at a fixed height was measured for a large number of different ground board orientations. These measurements were used to assess the variation in the sound pressure level over the ground board.
Contra-rotating rotor noise reduction methods
Authors: Kingan Michael J. , Jung Riul , McKay Ryan S.
Published: December 2023

This paper describes an experimental and numerical investigation into the tones produced by a contra-rotating rotor system for use on small unmanned aerial vehicles. The effect of changing the blade shape and the diameter of the lower rotor is investigated and it is shown that different
blade geometries can be used to significantly reduce tone noise levels. The numerical simulations are validated against the experimental measurements.
Numerical study on the estimation of the low-wavenumber wall pressure field using vibration data
Authors: Abtahi Hesam , Karimi Mahmoud , Maxit Laurent
Published: December 2023

It is known that the low-wavenumber components of the wall pressure field beneath a turbulent boundary layer is the main cause of structural vibration in low Mach number flows. This is because the structure filters the convective ridge of the turbulent boundary layer excitation at frequencies
well above the aerodynamic coincidence frequency. This work aims to explore the possibility of estimating the low-wavenumber wall pressure filed by obtaining vibration data from a structure excited by a turbulent boundary layer. To achieve this, an analytical model of a simply-supported plate
under turbulent boundary layer is developed and the acceleration data obtained from the plate is used to evaluate the wall pressure field in the low-wavenumber domain. The wall pressure field is modelled using the Goody and Mellen models for auto-spectrum density and cross-spectrum density,
respectively. Finally, the estimated pressure field is compared with the input turbulent boundary layer to evaluate the accuracy of the proposed method.
Anomaly detection and visualization for sound data with pre-trained deep neural networks
Authors: Kimura Keisuke , Kasahara Taro , Watabe Hikaru
Published: December 2023

Anomaly detection in the industrial domain is a critical issue. Although anomaly detection needs expert's experiences or huge person-hours, recent researches of deep neural networks can save much labor. This paper proposes an anomaly detection method for sound data with pre-trained
deep neural networks, and an anomaly visualization method to specify the frequency components of anomalous sounds. Common anomaly detection methods train deep neural networks which can detect anomalies in specific domains. However, training such networks from scratch costs a lot because the
neural networks have numerous parameters and use lots of data to improve the performance. To address this problem, anomaly detection using the pre-trained image classification networks has been proposed. This method uses feature representations of classification networks and the Mahalanobis
distance as the anomaly scores. In this paper, we propose a method which can apply the above method to sound data and evaluate its performance with a dataset for industrial sound which contains machine sounds under normal and anomalous operating conditions in real factory environments. We
also propose a visualization method to specify the frequency components when abnormal sounds occur.
Development of a continuous classroom signal-to-noise ratio measurement system
Authors: Yen Benjamin , Hui C. T. Justine , Bergin Esther , Jensen Eleesa , Purdy Suzanne C. , Keith William , Hioka Yusuke , Whitlock James , Dodd George
Published: December 2023

A successful learning experience requires children to be able to hear what the teacher is saying. To that end, children need a high signal-to-noise ratio (SNR) or speech audibility to hear the teacher under background noise, but SNR in the classrooms may not always be favourable depending
on the activities taking place during a school day. We propose a classroom acoustic measurement system to monitor the time-varying SNR under interactive teaching scenarios. Emulating a child listening to the speech made by a teacher, the system utilises two consumer-grade wireless microphones,
one attached to the teacher and the other located where the children would be seated. The signal received by the teacher's microphone is used as a voice activity detector to indicate the presence of the teacher's voice or noise-only audio instances. Subsequently, the children's microphone
observes these instances to monitor the average classroom noise and estimate the resulting SNR. A pilot study was conducted at a primary school in Auckland, New Zealand where the SNR measurements were recorded and matched against behavioural coding of the classroom activities. Results show
a reasonable agreement of the SNR to the activities performed under real-life classroom teaching scenarios.
Quantification of sound quality for lawnmower radiated noise considering listening conditions
Authors: Yoshida Junji , Terada Motoki , Naoe Gaku , Ohba Mai
Published: December 2023

In this study, we investigated an influence of listening conditions on the sound quality evaluation of lawnmower radiated noise and attempted to quantify the quality. Subjective evaluation tests were conducted using various lawnmowers equipped with engine or electric motor. In the active
listening condition test, the participants operated the lawnmower by themselves and evaluated "discomfort" and "powerful" of the sound. They again evaluated the sound quality of the identical reproduced sound in a test room in the passive test. As the results, discomfort
of the sound was significantly increased in the passive condition although powerful was almost same. Subsequently, we attempted to quantify these sound quality by using psychoacoustic metrics in each condition. The result indicated that both sound quality could be expressed very well using
loudness and sharpness. Loud and high pitch sound was evaluated as more discomfort and loud and low pitch sound was more powerful. In addition, discomfort of the sound was clarified to be evaluated about 30% more in the passive condition than that in the active condition.
Effects of sound insulation and light reflection of desktop partitions on subjective impression during conversation
Authors: Nakajima Miyuri , Sakuma Tetsuya , Kozaki Miki , Matsuyama Asami , Sakai Miki
Published: December 2023

In recent years, transparent desktop partitions have often been placed in public spaces to prevent the spread of COVID-19. Moreover, to clarify the view during conversation, surface materials with low light-reflectivity are developed for the partitions. In this paper, we conducted sound
insulation measurements for partitions with four different materials, and two psychological experiments in order to examine the audio-visual effects on the ease of conversation. First, in non-visual conversation between two persons, better subjective evaluation of speech transmission was confirmed
for partitions with lower surface density which have less insertion loss. However, in normal audio-visual conversation, the low light-reflective partitions got higher evaluations of not only visual but also auditory impressions, regardless of sound insulation performance. In addition, subjective
evaluations among different materials varied in the quiet condition more remarkably than in the noisy condition.
Measurement of Acoustic Signals to Characterize Household Appliance Based on Sound Power and Directivity Analysis
Authors: KHAN Tawhidul Islam , HAKIM Luqman , SAKIB Nazmush , RAHMAN Md Abdur
Published: December 2023

Measurement of acoustic signals to characterize the household appliance is very important for developing appropriate measures to avoid health hazards of in-house personnels. Acquisition and characterization of loud noise generated from a vacuum cleaner as a household machine is presented
in the present paper. The common assumption regarding the community noise level is that the directivity of the sound radiation from a machine or any acoustic source is axisymmetric. However, it is true that this assumption does not valid when the condition of flow does not hold on. Particularly,
if the characteristics of the sound source changes regarding to the signal features like frequency, intensity the directivity pattern of the sound radiation also changes. This characteristic has great influence to the noise reduction process as well. In the present paper the directivity of
sound signal has been analyzed in anechoic chamber. Remarkable variations in acoustic signal propagation from the vacuum cleaner are recorded in the case of varying signal frequency with significant acoustic features. Furthermore, signal power from the tested devise is also clarified accordingly.
Keywords: Acoustic Measurement, Sound Pressure Level, Directivity Analysis, Signal frequency, Household Appliance
Acoustic propagation analysis of sonic boom at atmospheric variation during 10-year flight
Authors: Iura Rei , Ukai Takahiro , Yamashita Hiroshi , Kern Bastian , Misaka Takashi , Obayashi Shigeru
Published: December 2023

Loud noise due to sonic boom is strongly affected by atmospheric conditions such as humidity, temperature, and wind including velocity fluctuation in the atmospheric boundary layer. In this study, we simulated the atmospheric conditions for the past 10-years based on historical meteorological
data, and the sonic boom of the pseudo-Concorde and the Low-Boom Concept (LBC) models along the flight routes were numerically investigated under the simulated atmospheric conditions. The results show that the overpressure of a sonic boom pressure signature varies seasonally, and the overpressure
decreases in winter. Molecular relaxation due to atmospheric humidity affects mainly pressure attenuation; however, the overpressure of the LBC is less sensitive to the atmospheric variation than that of the pseudo-Concorde.
Case study of the insulation performance in different types of flanking path construction
Authors: Wang Po-Yao , Hsu Ting-Kuei
Published: December 2023

In many Asian countries, people often live in a high residential density environment due to the narrow land and dense population. As a result, It is common and unavoidable for noisy rooms and noise sensitive rooms to be adjacent (e.g., the audio-visual room is located under the living
room of the upstairs residents). In order to improve sound insulation performance, feasible methods include improving direct and flanking sound transmission. Complete insulation performance research about has addressed different types of direct path construction in previous studies. However,
to achieve higher insulation performance, the effect of the flanking path is key. The influence of the different flanking path constructions influence on sound transmission has rarely been explored. Therefore, this paper's objective is to study the overall insulation performance of different
flanking path constructions (e.g., RC or lightweight construction), and the influence of adding additional layers. In this research, we focus on the vertical room pair situation and review direct and flanking path transmissions according to ISO 12354. Furthermore, we use the simulation software
CadnaB to verify the influences of different types of construction, and then make a case in field measurements.
Dynamics of a helical spring involving intermittent frictional contact with an oscillating barrier
Authors: Nagata Marisa , Saito Akira
Published: December 2023

This study concerns the transverse and longitudinal dynamics of helical springs. When a string is wrapped in helix to form a helical spring, its bulk longitudinal stiffness reduces. This leads to complicated dynamics of the spring in both transverse and longitudinal directions especially
when it involves frictional contacts against a barrier. To simulate such dynamics, experiments and numerical simulations were conducted focusing on the intermittent contact between the helical spring and an oscillating barrier. First, to investigate the effects of longitudinal stiffness on
the dynamics of the spring, vibration tests were conducted using the helical spring and a piano string with higher longitudinal stiffness. Vibration of the spring showed slower attenuation and involved more frequency components than the piano string. Next, numerical simulations were conducted
with intermittent contact and friction between the spring and the barrier along with the deformation of the spring in the longitudinal direction. The computed vibration in the longitudinal direction with friction resulted in also slower attenuation and more frequency components than those
of the case without friction. These results indicate that by conducting simulations with longitudinal deformation and friction, the vibration of a helical spring contacting with the barrier can be simulated with high accuracy.
Soundscape: a lower level is not in any case a better sound
Authors: Genuit Klaus
Published: December 2023

The new ISO standard ISO 12913 (Part 1: Definition and conceptual framework, Part 2: Data collection and reporting requirements, Part 3: Data analysis) describes for the first time a differentiated approach to the description of an acoustic environment in considering the context and
perception by the people living there. For measurement, a binaural recording method is normatively specified and for analysis several psychoacoustic parameters are recommended, which bring forth an analysis comparable to the human hearing. Soundscape means not only reducing the level of an
acoustic environment but also to create a pleasant sound quality. This procedure will be explained with practical examples.
Reproduction and experience of a classic Japanese-style room and sound environment
Authors: Ishihara Manabu
Published: December 2023

The structure of buildings and rooms changes with countries and eras. Cultural properties, classical literature, and music were created in specific periods and are connected to the present day. Reproducing architectural structures and environments that reflect the period in which the
classical literature and music were created can help us understand the creative environment of the time. As room structures have changed, room acoustics have naturally changed as well. In this study, The open conditions, common to the opening and closing of doors and windows, resulted in the
sound resonating well. The calculation results also showed that the sound attenuates from the sound source to the edge of the wall, but seems to be amplified around the wall. This means that the sound attenuates with distance from the sound source. This can be explained by the fact that the
waves reflected from the wall were included near the wall. Next, experiments were conducted to reproduce roughness. The results showed that roughness can be reproduced by limiting the range of frequencies. In other words, one design condition for the reproduction method was presented based
on the assumption that the room was touched.
Trends of study in Japan based on "Environmental Noise Guidelines for European Region (2018)"
Authors: Shiotani Ayumi , Yagawa Keiji , Matsui Toshihiko
Published: December 2023

This paper describes the following study conducted by the author on behalf of the Ministry of the Environment in Japan from 2020 to 2021. The WHO Regional Office for Europe published "Environmental Noise Guidelines for the European Region (2018)" (hereafter referee as to "Guidelines")
in October 2018. Compared to the previous guideline (1999), these Guidelines show that Lden and Lnight are used as the index for the recommendations, cardiovascular disease is selected as a critical health outcome for developing recommendations on the health impacts of environmental noise.
In Japan, since the publication of the Guidelines (2018), we have discussed the scientific findings presented in the Guidelines and the basis for setting the recommendations, and compared the recommendations with the following Japanese environmental quality standards: noise facing roads, aircraft
noise and Shinkansen railway noise. In addition, we investigated the difference in the status of ischemic heart disease between in Japan and in Europe. Based on the stored information, we summarized issues to be discussed in the near future.
Analysis of the community responses to road traffic noise using structural equation modeling -comparison of the covariance structure models for different housing types-
Authors: Komi Yui , Yokoshima Shigenori , Tsujimura Sohei , Yamauchi Katsuya , Suda Naoki , Yamazaki Toru
Published: December 2023

As for the situation of road traffic noise problems in Japan, the percentage of areas where achieve the environmental quality standards for road traffic noise tends to increase year by year. On the other hand, number of complains about road traffic noise has not been changed recent
years. In order to determine the factors affecting annoyance due to road traffic noise, we analyzed how the annoyance was determined using the dataset derived from a social survey on community response. The social survey was conducted along arterial roads in 2019 and 2020. Total sample sizes
were 360 and 228 in detached houses and apartments, respectively. Noise exposure was estimated based on the ASJ RTN-Model. We constructed a covariance structure model which represents the hierarchical structure from noise exposure to annoyance via activity disturbances and applied multiple-group
analysis for structural equation modeling to the model. This paper focused on the difference in the direct and indirect impacts of noise exposure on annoyance between the detached houses and apartments. The analysis showed that the determination of annoyance which was affected by noise exposure
via activity disturbances differed according to housing types.
Applying time-resolved noise maps to assess the impact of road-traffic measures on wake-up reactions in urban environments
Authors: Müller Tobias S. , Nabikhani A. , Henning Arne
Published: December 2023

The present study investigates the effect of traffic measures in an urban area on the wake-up reactions at nighttime of the residents in the vicinity. These measures include road blocks and speed limits along a few selected streets in a part of Berlin representing the studied area.
A temporally resolved noise mapping method based on the CNOSSOS-EU directive is used to calculate the noise level at discrete locations. The number of reactions and the awakening frequency are estimated based on the metrics established in a previous study. The results show a reduction in adverse
sleep disturbances leading to awakening due to the traffic restrictions during the night.
Designing the rotary switch operation feeling based on cross-modal correspondences between tactile and auditory sensations
Authors: Miyairi Toru , Sakamoto Hideki , Shimomura Hisato , Otomo Takashi , Toi Takeshi
Published: December 2023

In recent years, the number of physical switches in in-vehicle devices has been reduced by consolidating several different control functions into a single control interface through active tactile devices. However, for such tactile devices to provide an improved user experience, the
design must be carefully created to provide an appropriate operational feeling for each control function. The aim of this study was to find the best suitable combination of tactile and auditory sensations for the rotary knob-type tactile device to improve the user experience. The Semantic
Differential method was used in the first experiment to evaluate electronically generated operating sounds, which enables the determination of the relationship between auditory impressions and acoustic features. In the second experiment, "the suitability of the combination of stimuli"
was used to evaluate the impressions as an index during the simultaneous presentation of tactile and operating sounds. The results revealed a tendency for the stimuli to be perceived as "well-combined," with cross-modal correspondences between tactile and auditory sensations.
The resonance mode splitting rule of the rotating tire cavity considering the vertical load
Authors: Hu Xueman , Liu Xiandong , Bao Yue , Shan Yingchun , He Tian
Published: December 2023

According to the modal splitting theory of the tire cavity at different rotation speeds and the modal splitting theory of the tire cavity under different loads, the expression of the resonance frequency of the tire cavity of the rotating tire under load conditions is proposed. Based
on the elastic contact theory, the characteristic geometric parameters of grounded tires are obtained. The resonance frequency of the tire cavity is predicted by using the common rule of the characteristic geometric parameters of grounded tires and the characteristic section parameters of
the tire cavity, to further clarify the basic rule of changes of vibration mode shapes accompanied by the resonance mode splitting of the tire cavity.
High-resolution DOA estimation in the hydrophone array shape with uncertainty based on dynamic compressed sensing
Authors: Cheng Liang , Wu Qisong , Yu Fujian , Zhang Ye
Published: December 2023

Compressed sensing (CS) technology is a popular method for the direction of arrival (DOA) estimation of underwater acoustic radiation noise due to its high resolution. However, in practical applications such as buried arrays and other arrays, uncertainty in the hydrophone array shape
can lead to model mismatch which significantly reduces DOA estimation accuracy. This paper focuses on high-resolution wideband DOA estimation in the radiated noise from underwater targets of interest using dynamic compressed sensing. The study introduces phase error into the signal model to
simulate the model mismatch, and improves DOA estimation accuracy by jointly estimating both the DOA and phase error. Simulation results demonstrate that the proposed algorithm is effective in improving the accuracy of DOA estimation.
Study on the design values of windows for high-rise residential buildings on street level based on Odeon simulation calculations
Authors: Luo Huaying , Sun Haitao
Published: December 2023

With the development of road traffic, the surrounding residents are inevitably disturbed by the increasing noise. Long-term exposure to noise can affect the daily lives of residents. Installing sound-insulating windows is a reliable way to reduce indoor noise, so it is vital to choose
the right one. However, the weighted sound insulation measured in the laboratory cannot be used directly in predictive calculations of indoor noise. This study uses Odeon to simulate the outdoor and indoor sound fields. The simulated data is analyzed based on the formulae in the Beijing Local
Standards. The results show a correction of -1.3 to 0.6 dBA for window design values in indoor rough decoration condition and -0.6 to 1.3 dBA in indoor fine decoration condition. This study provides a useful method and reference for environmental assessment work.
Active noise control with variable directivity loudspeakers
Authors: Du Bokai , Yan Qun , Dong Ningjuan , Xue Qing , Cheng Yixiao
Published: December 2023

Active noise control (ANC) is an effective way to reduce the low frequency noise level for passengers in cars or aircrafts. In these applications, secondary sources are usually monopole loudspeakers. Variable directivity loudspeaker is a kind of loudspeaker which is able to control
its own radiation directivity. It is potential to be able to control the sound field better compared monopole loudspeaker. Inspired by this, variable directivity loudspeakers are applied to an ANC system. A simulation is conducted to investigate the performance of the ANC system with variable
directivity loudspeakers. Simulation results show that the ANC system with variable directivity loudspeakers outperforms the one with monopole loudspeakers in noise control using the same number of loudspeakers.
The concept of soundscape and intervention
Authors: Schulte-Fortkamp Brigitte
Published: December 2023

The soundscape concept provides a holistic understanding of the perception of an acoustic environment. The assessment of an acoustic environment is not only based on the contribution from different disciplines but also to be seen as a heterogeneous field of research. In regard to intervention
it is a matter of collaboration to bring experiences, perception, and evaluation into the field of application. With that it becomes a technical innovation which underlies an adaption process through communities, stakeholders and the people concerned. The researches on soundscape have clearly
addressed the need also to transfer their outcomes into the practice of soundscape design. Overall, soundscape research needs more political evidence of its potential to promote healthy urban environments through cognitive restoration. This will help to disseminate the outcomes from soundscape
research and eventually to integrate this scientific field in the broader framework of policy making and urban planning. It is an open discussion whether and how the ISO Standard can support further application of soundscape approaches within communities. In providing procedures to be applied
within community noise investigation and regulations - it would be a big step forward to enhance people's quality of life in their acoustic environments.
Optimization methods for acoustic material selection in interior spaces
Authors: Sree N K Vijaya , Venkatesham B
Published: December 2023

The quality of the acoustic environment required in a room varies with the application, which could include industrial spaces, office rooms, classrooms, theatres, etc. Treatment of surfaces in rooms with acoustic materials is important in achieving the desired acoustic quality. In an
industrial environment, it is necessary to treat walls with interior and exterior acoustic linings that are both cost and acoustical quality efficient. This work intends to develop optimization strategies for acoustic material selection using cost minimization as the objective function, in
conjunction with acoustical requirements and material selection limitations. The first technique is a genetic algorithm (GA) with dual stage variable chromosome, which improves the ease of constraint implementation in the algorithm. The second method is the Shuffled Frog Leaping Algorithm
(SFLA) with an implementation over a discrete domain. A better convergence has been observed with SFLA over GA due to group improvisation with local and global best population. The described algorithms are demonstrated and compared for office and classroom acoustic treatments.
PROPELLER INFLUENCE ON SURFACE PRESSURE FLUCTUATION UNDER BOUNDARY LAYER INGESTION CONDITION
Authors: Castelucci Leandro Alan , Venner Cornelis H.
Published: December 2023

Research on propeller noise under boundary layer ingestion condition is essential for designing new aircraft concepts. Measurements of pressure spectra on a flat plate below a propeller give important information about the noise coming from the blades. These also are important for designing
surface noise mitigation structures, such as acoustic black holes, meta-materials, and liners. This paper investigates the effects of a propeller on the flat plate surface pressure under boundary layer ingestion, using bottom of the wind tunnel channel as flat plate. Tripping devices on the
wind tunnel bottom wall control the boundary layer thicknesses. The surface pressure is measured using an instrumented plate positioned underneath the propeller. The plate has 87 pressure taps to measure the unsteady and steady pressure using the remote microphone probe (RMP) technique. The
results show the influence of the propeller inflow, the advance ratio, and the number of blades on the different regions underneath the propeller, and on coherent turbulent structures of the incoming flow. The boundary layer thicknesses affects the static pressure upstream of the propeller
- creating high pressure regions. The propeller affects the turbulent structures downstream of the blades, increasing its correlation length.
NVH numerical analysis of the mounting layout of hydrostatic transmissions in continuously variable transmissions
Authors: Battarra Mattia , Guerra Davide , Bonacini Filippo , Meleti Stefano , Mucchi Emiliano
Published: December 2023

The present work proposes a numerical approach to model the dynamic behavior of the mounting layout of hydrostatic transmissions in continuously variable transmissions for off-road vehicles. The methodology takes advantage of a finite element model constituted by a rigid body, representing
the hydrostatic transmission, connected to the overall transmission frame through a combination of torsional couplings, rolling-element bearings and brackets, considered as flexible components. Bearings, in particular, are substituted with nonlinear springs, while brackets and frames are 3D
meshed according to the actual geometry of the system. The model allows to estimate the frequency dependent forces applied on the frame in reference to the loads generated within the hydrostatic transmission. The method is applied on a case study, showing that the torsional joints play a relevant
role on the overall NVH behavior of the system and their kinematic characteristics should be carefully defined to tune the loads transmitted on the transmission frame.
Research and sound quality analysis of little theaters in Guangdong universities
Authors: Zhu JiaWei , Sun HaiTao
Published: December 2023

Little theaters have become a new type of theater form with their low investment costs, diverse space designs, and rich performance genres. In this paper the building acoustic design is focused on as a key point to research the audience hall space, the spatial shape, stage form and
audience hall seating capacity in little theaters, and it is explored that the applicability of such new audience hall spaces to domestic theater design guidelines. One of the typical little theaters is studied by ODEON simulation. The simulation results show that the mid-frequency value of
reverberation time (T30) is higher, which is not meet with the mid-frequency range of the domestic theater design guidelines for reverberation time.
Counting and Localization of Multiple Unknown Harmonic Sound Sources in Entire 3D Space Using Just Five Microphones
Authors: Thakur Shikha , Singh Sneha
Published: December 2023

Counting and localization of multiple sound sources in an unknown environment has many applications, namely fault diagnosis of complex machineries, hearing aids' development, and localization of enemy vehicles in defense. However, multiple sound source localization is extremely challenging
because it requires numerous microphones, which increases the cost, computational time, and installation difficulties. Here, we present a new method to count the number of stationary harmonic sound sources and localize them in a free-field environment using a novel oblique square pyramid shaped
array of only 5 microphones. We find FFT peaks of microphone signals and compare the ratio of the magnitude of the most dominant peak with remaining peaks' one-by-one. If these ratios are below 25 dB difference, they are considered as sound source and counted. A new time delay and intensity
ratio computation is applied to the segregated source signals to calculate exact coordinates of each source. Simulation studies of four concurrent sources show that our method predicts all sources' coordinates at every octant location with mean error of 3.4%, and less than 5% error beyond
20 dB Signal-to-Noise ratio. Mean computational time is 0.92 second. Therefore, our method is low-cost, quicker, more accurate and more reliable than existing techniques.
Optimization of a Microperforated Panel backed by a Panel Resonator with Multi-resonators using Particle Swarm Optimization
Authors: Yeang Wai Yeen , Halim Dunant , Yi Xiaosu , Chen Hao
Published: December 2023

A micro-perforated panel (MPP) is perceived as the next generation of sound absorbers which has an outstanding absorbing performance in the mid to high frequency range. However, MPPs often suffer from narrow absorption bandwidth and poor sound absorption in the low frequency range below
500Hz. Therefore, an MPP is backed by a panel-type resonator with installed multiple resonators (MPR), forming an MPP-MPR composite structure is proposed, which is able to improve the sound absorption performance in the low frequency region. The present study is aimed to optimize the resonators'
resonant frequencies to further improve the low frequency absorption performance. A coupled vibroacoustic model is presented and particle swarm optimization (PSO) is employed to optimize the sound absorption performance. It is found that the optimization of all four resonators converged to
four different resonant frequencies, improving absorption valleys. The optimization algorithm has demonstrated its ability to optimize the resonant frequencies of the resonators in improving the low frequency absorption, while also extending the half-absorption bandwidth.
Numerical computation of damped vibration and sound radiation for structures having a porous layer sandwiched by double walls with an acoustic black hole
Authors: Yamaguchi Takao , Tamura Tomoki , Kamio Chihiro , Hisamura Yuta
Published: December 2023

Vibration and noise reduction are important technology to realize comfort products with safe structures. In this paper, we carry out numerical simulation of damped vibration and sound radiation for structures having a porous material sandwiched by double walls. The double walls are
consisted of a steel base plate and a steel cover plate. The cover plate in double walls has a Krylov type acoustic black hole. Damping material is on the surface of the black hole. One point in the base plate is excited by white noise. Numerical analysis is performed to clarify changes of
vibration transmission from the base plate to the cover plate due to the acoustic black hole using FEM and MSKE method(Modal Strain and Kinetic Energy method) proposed by Yamaguchi et al. Sound radiation from the cover plate is also investigated. The vibration transmission were reduced for
the model having acoustic black hole in the cover plate. Vibration energy flows into the black hole in the cover plate. This causes that vibration acceleration of the cover plate is damped effectively. Sound radiation from the cover plate also decreased. This is because high damping and shorter
wave length of vibration in the acoustic black hole.
Investigation of sound direction sense by effect of sound source height for voice evacuation guidance system in VR space
Authors: Aida Seitaro , Osumi Ayumu , Ito Youichi
Published: December 2023

We previously have been developed a voice evacuation guidance system using the precedence effect, which is a psychoacoustic effect. The system can be used to facilitate rapid evacuation to a safe area in environments with poor visibility, including those with smoke and dust, because
it uses sound to guide evacuees. To apply this system to a building, it is necessary to construct a sound space suitable for the system. In particular, it adjusts sound in the field, including speaker position and sound pressure level setting. In the present study, we applied virtual reality
(VR) technology in designing the system. If the basic design can be completed in the virtual space using VR technology, then the constructing time for the system can be substantially reduced because there is no need to experiment. In this report, we verified the sense of direction by adjusting
the installation height of the sound source in the VR space. We confirmed that we could obtain the same level of evaluation characteristics for the precedence effect in both the real and virtual spaces.
Torque dependent behavior of the vehicle background noise and its influence on masking thresholds in electric vehicles
Authors: Abbink Victor , Landes David , Altinsoy Ercan
Published: December 2023

The quality and comfort perception in vehicles is strongly influenced by the overall sound quality of the vehicle. Besides aerodynamic and tire noise, tonal powertrain noise plays an important role and can have a strong negative impact on sound quality. An assessment of the perceptibility
of tonal noise with respect to masking noise is therefore essential for the vehicle development process. Due to the absence of masking by the internal combustion engine in electric vehicles and the wider frequency range of the powertrain noise, new methods are required for this purpose. In
order to evaluate state of the art masking models and a newly developed method regarding the audibility of tonal components, masking thresholds for tonal noise in the vehicle interior are experimentally determined in listening tests. A currently developed extension of the method will also
allow roller dynamometer measurements to be used for the evaluation. Currently, the masking signals are mostly generated with torqueless coast down measurements to consider the worst-case scenario. However, a torque dependency has to be taken into consideration. In this paper the torque dependency
of the masking noise and the resulting influence on masking threshold is shown for road and roller dynamometer measurements.
Sound field visualization system by MVDR beamforming with augmented reality and point clouds
Authors: Inoue Atsuto , Teraoka Wataru , Oikawa Yasuhiro , Satou Takahiro , Iwane Yasuyuki , Kobayashi Masahito
Published: December 2023

In previous research, we proposed an augmented reality (AR) and mixed reality (MR) system visualizing the sound field data measured by the beamforming method. Our system visualized the sound pressure as a colormap on the AR/MR device in real-time. Free viewpoint and visualization of
a colormap along the spatial geometry observed by the AR/MR sensor enabled us to understand the location of the sound source. On the other hand, the spacial geometry information of the measurement space was used only for display purposes and not in the processing of sound source location estimation.
And then the previous system displaying a flat colormap projected on the spatial geometry has not been able to make measurements that precisely in space. In this paper, we propose a sound field measurement and AR/MR visualization system using point cloud data acquired by light detection and
ranging (LiDAR) sensor. The MVDR (minimum variance distortionless response) beamforming calculates the beamforming output by using point cloud data. The sound sources are assumed to be located on point clouds, and the system allows fast localization of a large number of sources. In addition,
it is possible to interpret the sound field in various ways based on the scattered sound pressure information. We show some basic experiments conducted in an anechoic chamber.
Improved SPH method based on moving least square method for acoustic problems
Authors: Yang Jie , Zhang Xinyu
Published: December 2023

Smoothed particle hydrodynamics is a widely used meshfree method. However, the order of the reproducing differential function is only the first order. To improve that, a corrective process termed as moving-least-square smoothed particle hydrodynamics, MLS-SPH, is introduced. Taylor
expansion is used to modify the relation between arbitrarily distributed particles, and the concept of moving least square is used to approximate the value of the function and partial differential functions. This modified method can improve approximate accuracy effectively. Moreover, the order
of approximate partial differential function becomes changeable, which expands the scope of its application. To investigate the advantages, a 2D complex surface approximation, a 2D model of Poisson problem with differential boundaries, and the acoustical modal of a rigid wall-bounded cavity
are simulated.
Study on the noise generated in curved sections of railways
Authors: SHIMIZU Yasuhiro , SUEKI Takeshi , NITTA Takuma
Published: December 2023

When trains run on a curved track, wheel and rail vibrations sometimes cause squeal noise (below 10 kHz) and high-frequency noise (above 10 kHz), contributing greatly to overall wayside noise and often causing complaints from residents. The measurements of noise and vibrations were
conducted in commercial lines to understand the mechanisms underlying the generation of these noises and develop methods to reduce them. It is found that the occurrence of these noises varied from train to train, and the magnitude and dominant frequency at which they occurred varied greatly
from wheel to wheel. Furthermore, the analysis of the results showed that these noises become prominent both inside and outside when outer wheel flanges contact outer rail.