bluuebunny/crossref_metadata_2025 huggingface dataset:
A concept to evaluate activity-based acoustic settings in preschools for children aged three to six
Authors: Loh Karin , Seitz Julia , Rust Frederike , Fels Janina
Published: December 2023

Describing common noise patterns caused by different activities and situations in educational buildings is a complex topic. First categorizations of activities have been developed for primary schools addressing children starting from the age of six. They were based on the teacher-to-children-communication
pathways or the teaching activity, such as math class versus music lessons. Until now, preschools and, thus, children younger than six have been rarely examined in previous literature. This study seeks to investigate activities in preschools for the age group of three- to six-year-olds and
discusses a categorization of activity patterns concerning the educators-to-children interaction and communication pathways. For this, acoustic measurements were conducted in preschools. Differences in selected noise descriptors (e.g., sound pressure level and psychoacoustic parameters) were
explored and discussed with respect to the proposed categorization. Furthermore, this study focuses on adding children's points of view into the evaluation by integrating effects assessed using a child head and torso simulator.
Measuring directivity of half-inch measurement microphones
Authors: Milhomem Thiago Antonio Bacelar
Published: December 2023

The directivity of a microphone is the relative sensitivity variation as a function of incidence angle. This is an important characteristic when every sound arriving at the microphone position is relevant. This paper presents the measuring directivity of half-inch measurement microphones.
The microphone is placed in a free sound field and exposed to a sound pressure. The unloaded output voltage is measured. Then, the microphone is rotated in 30o steps, while both the acoustic centers of the microphone and the sound source remain in fixed positions in the sound field, and is
exposed to the same sound pressure. The unloaded output voltage for each angle of incidence is measured and them the difference relative to 0 deg. of incidence is calculated as a function of frequency. The directivity of eight measurement microphones from the same manufacturer but of different
types and frequency response characteristics (i.e. pressure field, random incidence or free-field) were measured. Results showed that the microphones object of this investigation have similar directivities in the frequency range from 16 Hz to 12.5 kHz regardless of their frequency response
characteristics.
Practical tutorial on cylindrical structure vibro-acoustics Part 2 - Acoustics
Authors: Hambric Stephen A.
Published: December 2023

In part 1 of this tutorial (proceedings of Inter-noise 2022) I explained vibrations in cylindrical shell structures. In that paper I limited the mathematics and focused on the key behavior of shells based on critical parameters like the ring frequency, helical wavenumbers, and mean
mobilities over different frequency ranges. I compared measured data to the simple theories. In part 2, I focus on the acoustics of cylindrical shells, including sound within shells and the sound radiated outside them. Exterior sound radiation depends strongly on the circumferential order
of the shell modes. Breathing modes near the ring frequency radiate sound extremely well, but have very high impedances, so can be difficult to excite. Beam-like modes, where the entire shell cross-section vibrates transversely, radiate less efficiently, but can be easily driven. Higher order,
or 'lobar' modes radiate even less efficiently, but nevertheless are commonly observed in radiated sound spectra due to their low impedances. I also review statistical estimates of radiation efficiency of groups of shell modes, which show clear peaks at both the ring frequency as well as at
the critical frequency of bending waves. The mathematics of sound inside cylindrical shells is some of the most challenging in vibro-acoustics. At low frequencies, however, the interior sound is dominated by simple one-dimensional planar acoustic waves. At higher frequencies, the sound depends
on how well a shell vibration field matches the interior acoustic field based on proximity of resonance frequencies and the similarity of mode shape orders, as well as the 'cut on' frequencies of higher order internal acoustic modes. Finally, I review the well-known phenomenon of how a low
shell wall impedance can reduce the effective acoustic sound speed of one-dimensional waves inside cylindrical shells.
Tire-road noise assessment
Authors: Hashimoto Takeo , Hatano Shigeko
Published: December 2023

The powertrain of passenger cars is now in place of an electric motor instead of a conventional reciprocal gasoline engine for reducing carbon dioxide for not to increase atmospheric temperature. By this change, sound emitted from passenger cars are becoming quieter compared with the
former stage. And because of this, exterior and interior sound atmosphere are far quieter than before and while running on the road, interior tire-road noise and tire-pattern noise are more significant under quiet atmosphere. So, the treatment of tire-road noise is important for comfortable
atmosphere. This paper deals with the tire-road noise for better impression in that how we should deal with the tire-road noise in frequency content.
Recent situations of flight operation and noise exposure observed by the pilot noise monitors at Noi Bai International Airport in Vietnam
Authors: Nguyen Thu Lan , Vu Thi Thanh , Sakoda Keishi , Yamada Ichiro
Published: December 2023

This paper introduces the result of data analysis on recent situations of aircraft operation and noise exposure at Noi Bai International Airport (NIA), using observations by the pilot noise monitoring equipment installed in 2019 under a cooperation project on airport environment preservation
and aircraft noise monitoring in Vietnam. The results of the noise monitoring over the period from 2019 to 2023 reflect the significant changes in aircraft operation at NIA due to the pandemic of COVID-19. Noise exposure decreased after the epidemic outbreak, with a significant drop at the
time when the government ordered travel restrictions, and gradually recovered under a new normal context. The result of data analysis suggests the degree of change in the sound environment in the vicinity of NIA under the different scenarios of aircraft operation. It also provides us with
the information necessary to create noise prediction maps. The level of noise exposure observed at each monitoring station was largely in line with the calculated noise levels. Besides, analysis of aircraft operation and noise exposure situations by period revealed that the level of noise
exposure varies with the time of day. Additionally, the analysis raises concerns about the impact of nighttime noise, which may disrupt the sleep of residents living near the NIA.
Influence of truck platooning with various vehicular gaps on bridge vibration
Authors: Fukada Saiji , Mori Tatsuaki , Iwabuki Hiroshi , Sano Yasuyuki , Matsumoto Yasunao , Kamiakito Noboru , Yabe Akito
Published: December 2023

Truck platooning tests using automated driving technology have been conducted on expressways to address issues such as truck driver shortages, an aging workforce, and rising fuel costs. These tests involved three trucks traveling at a speed of 80 km/h, with the trailing two trucks unmanned
and maintaining approximately 9 m between vehicles. When multiple trucks cross a bridge with a specific gap between them, the combined vibration of the vehicles and the bridge can cause significant bridge vibrations. In recent years, many bridges have been constructed as continuous structures
to improve their seismic performance. Consequently, numerous vibration modes of multiple bridges exist in proximity. Hence, it is believed that many coupled vibrations between trucks and bridges are generated. However, it is possible to control the bridge vibration response by altering the
gap between vehicles and their traveling speed. In this study, the effect of the gap between vehicles during actual truck platooning tests on changes in bridge vibrations is investigated.
Development of a method for predicting traffic vibration transmitted from viaducts
Authors: Fukada Saiji , Mori Tatsuaki , Iwabuki Hiroshi , Sano Yasuyuki , Matsumoto Yasunao , Kamiakito Noboru , Yabe Akito
Published: December 2023

It is important to predict the traffic vibrations generated by viaducts and to consider countermeasures against environmental vibration problems that are transmitted to surrounding houses. However, it is difficult to predict the vibration propagating from viaducts owing to various parameters,
such as the structural type of bridge, ground conditions, road surface conditions, and traffic load conditions (running speed, running position, vehicle weight, traffic volume, etc.). Therefore, in this study, vibration tests were conducted on an actual viaduct, detailed bridge and vehicle
models were developed that can reproduce the vibration phenomena on an actual bridge, and a method was developed to predict traffic vibration propagated from the viaduct using vehicle running simulations.
Loudness of double impulsive sounds and its relation to temporal masking curves
Authors: Hashimoto Takeo , Hatano Shigeko
Published: December 2023

The loudness of double impulsive sounds is examined from the viewpoint of temporal masking in that why the loudness of double impulsive sound becomes louder with the shorter duration compared with longer duration. The stimuli are set of various rise/fall times and various durations
with the energy inside the stimuli remained unchanged. And to compare the loudness, it is least with the equal rise/fall times that with the short rise and long fall time and long rise time and short fall time. This is also true for single impulsive sounds. And together with this, the loudness
is louder with the duration of the stimuli in that the louder the loudness the shorter the stimuli. The results of temporal masking curves are shown for explaining the cause of this loudness variations why it becomes louder with the shorter durations.
Modified insertion loss (IL) analysis for nonuniform trapezoidal (zigzag wall) and sinusoidal (crinkle-crankle wall) 3-D sound barriers
Authors: Giora Rosenhouse
Published: December 2023

The trigonometric Maekawa triangles and Pierce quadrilaterals are regularly used to calculate the insertion loss (IL) of plane, semi-infinite and finite sound barriers. By applying these approximate solutions and basic mathematical geometrical tools (e.g., Rosenhouse, 2019, 2020, 2021),
the author solves IL of more irregular barrier shapes of barriers like irregular zigzag, sinusoidal and other types of barriers. Solved examples are presented and the author's added proof for the optical inclination factor use in acoustic diffraction, that is given in appendix A.
Neural-network clustering for evaluating immersive sound fields
Authors: Kim Sungyoung , Howie Will
Published: December 2023

Evaluating immersive sound fields requires a group of trained and experienced listeners. This study investigates whether unsupervised clustering using a self-organizing map can be used to group listeners based on their perceptual responses to immersive reproduction of two orchestral
music recordings. The study trained a clustering model using 82 subjects' subjective responses, which consisted of five attribute ratings and one preference rating. Subsequently, the model was validated with a new data set from 19 subjects. The results showed that the model was 84% accurate
compared to manual clustering. The clustered group's cognitive characteristics were similar to a previous study, supporting the efficacy of the proposed neural-network clustering. The authors will continue to collect more data to further validate and update the model, which will reliably and
quickly evaluate a participant's degree of training and experience to determine their eligibility for relevant subjective evaluations of immersive auditory experiences.
Spatial audio reproduction for studying second language speech perception in varying acoustic environments
Authors: Hioka Yusuke , Hui C.T. Justine , Masuda Hinako , Watson Catherine I. , Osawa Eri , Arai Takayuki
Published: December 2023

This paper introduces recent attempts of utilising spatial audio reproduction in linguistic studies and discusses challenges of the new methodology. Thanks to its high reproducibility of arbitrary acoustic environments in a controlled laboratory setting, spatial audio reproduction has
a potential to address the difficulties of examining participants with different language background that have to be recruited in geographically separated locations. A case study that investigated the difference in speech intelligibility in noise between first and second language listeners
in varying acoustic environments is reported with its experimental results. The paper then attempts to verify the validity of the methodology using spatial audio reproduction by comparing experimental results conducted in real and virtual rooms.
Quadcopter Sound Characterization using a UAV Test Stand
Authors: Schmal Jared , Herrin D. W. , Comesaña Daniel Fernández
Published: December 2023

Unmanned Aerial Vehicles (UAVs) generate a complex acoustic field that is not entirely understood. Many components and their interactions contribute to the overall noise level and behavior of the acoustic field. A UAV test stand configured to emulate a small quadcopter with a wheelbase
of 61 cm was used to determine the acoustic response of a multicopter. Microflown Technologies Scan & Paint 3D solution was utilized to obtain sound pressure, particle velocity, and sound intensity measurements close to the source, along with propagation planes for three-dimensional visualizations
containing both amplitude and direction. Draw away measurements using a PU probe were also completed to analyze the sound field characteristics further from the source. The number of propellers in operation was varied to determine the impact of adding additional sources. Aeroacoustic sources,
near and far field behavior, interaction noise, directivity, and the sound field propagation of each case is discussed.
Research progress and development trends in urban tranquil areas from the soundscape perspective
Authors: Yan Wei , Meng Qi
Published: December 2023

Building urban tranquil areas has become a critical initiative to improve societal well-being as noise pollution has emerged as a severe environmental risk and health threat. This paper uses a systematic review and comprehensive analysis to concentrate on the research progress and trends
of urban tranquil areas from the soundscape perspective to fully understand the research dynamics of urban tranquil areas and advance future research and practice. This paper presents three major priorities and three major trends in urban tranquil areas research:1) The concept of urban tranquil
areas has a variety of connotations. The conceptual connotations reflect a shift from an objective acoustic perspective to an open soundscape perspective. 2) There are many ways to identify urban tranquil areas. Identification methods show a trend of moving from the construction of indicators
to big data identification; 3) The perception assessment of the urban tranquil areas is rich in content. The focus of the evaluation shows a trend from focusing on auditory experiences to focusing on multi-sensory experiences. The results of the study can further contribute to the development
of research and the construction of urban tranquil areas. Keywords: urban tranquil areas; soundscape; identification methods; perceptual evaluation; trends
Boundary treatments for the finite element analysis of shell vibration fields of architectural structures extracted with edge truncations
Authors: INOUE Naohisa , CAO Da , SAKUMA Tetsuya
Published: December 2023

The finite element analysis of a vibration field of a large-scale architectural structure is often conducted by extracting a local part to reduce the computational cost. A common way of extraction is to truncate the structure around the junction consisting of walls and floors. This
paper proposes two boundary treatments to be given to the truncated edge. One is giving an impedance boundary condition of a junction. The impedance values are determined by the transfer matrix method (TMM). The other is a non-reflecting edge truncation realized by the perfectly matched layer
(PML) shell element, which is a numerical model of the infinitely extending structure. Firstly, formulations of the two treatments are provided in detail. Secondly, impedances of basic shape junctions consisting of semi-infinite members are investigated by the TMM for a better understanding
of the physical behavior. Thirdly, the proposed PML element is validated in two problem settings: the distance attenuation in the free field and the cross-junction's absorption property. An appropriate parameter tuning for the calculation using the PML element is also discussed.
Case study of sound insulation performance of a first pure timber 3-story elementary school in Japan
Authors: Hiramitsu Atsuo , Kubo Hisashi , Muraoka Masaki
Published: December 2023

In Japan, "the Act on Promotion of Use of Wood in Buildings to Contribute to the Realization of a Decarbonized Society" promotes the use of wood in buildings in general. The school buildings as public buildings are being promoted to be constructed with timber construction
since timber school buildings effectively improve the educational environment. This paper presents the measurement results of the sound insulation performance in "the Uozu City Municipal Hoshinomori Elementary School", which is a first all-timber construction 3-story elementary school
in Japan. By adopting a dry-type double floor structure for the floor finish structure and an independent ceiling for the ceiling structure, the floor impact sound insulation performances of the classrooms were Lr-60 for both heavy-weight floor impact sound and light-weight floor impact sound
when evaluated using JIS A 1419-2. Moreover, the recommended reverberation time values of the Architectural Institute of Japan Environmental Standards were generally satisfied by installing dressed rockwool sound absorbing board on the ceiling.
A study on source separation of traffic vehicle noise using deep learning
Authors: Jeong ManYong , Yamazaki Toru , Kurihara Kai , Shirahashi Yoshihiro
Published: December 2023

In order to reduce the environmental damage caused by road traffic noise, it is not only necessary to measure the amount of traffic by vehicle type and the resulting noise level but also convert them into big data for monitoring them. To achieve this, a monitoring system needs to be
developed that can more accurately classify vehicle types and evaluate the noise level of each vehicle in motion. In recent years, the development of AI has significantly improved the performance of vehicle counting systems, and these systems are already being used in traffic volume surveys.
However, a system that simultaneously measures traffic noise and converts it into data has yet to be developed, and the specification and prototyping of such a system is of utmost importance. This paper presents a Traffic Monitoring System, a novel system that automatically collects data on
road traffic noise, which includes a noise source separation system to evaluate traffic noise, and strives to establish the related elemental technologies. Specifically, the Traffic Monitoring System uses cameras and microphones installed on edge devices to acquire road video and audio, and
the system then performs vehicle detection, vehicle speed estimation, and noise evaluation for each vehicle.
Prediction and analysis of flow-induced noise of a real-size high-speed train using compressible Large Eddy Simulation and vortex sound source
Authors: Lee Kwongi , Cheong Cheolung , Kim Jaehwan
Published: December 2023

As technology advances, high-speed trains have become faster, and the aerodynamic noise generated by their exterior flow fields has become a critical consideration in the design process. Accurately predicting the flow-induced noise of high-speed trains requires high-resolution sound
source generation in the near-field and noise propagation in the acoustic field without numerical dissipation. This necessitates the appropriate design of the grids from the point of aerodynamic noise generation and propagation in association with the length scales of the relevant components
of an actual train. To address this challenge, this research study employs a three-dimensional compressible Large Eddy Simulation (LES) technique with high-resolution grids to simultaneously calculate the external flow and acoustic fields of a real-size high-speed train consisting of five
cars running in open field. Further analysis is carried out to evaluate the contribution of major components, including the cap, pantograph, bogie, intercoach, and HVAC cover, which are known to be significant contributors to high-speed train flow noise. The study also employs the vortex sound
source to analyze the generation mechanism of flow-induced noise for each component, providing insights for reducing aerodynamic noise.
Validation of rolling-stock interior noise simulation in viaduct and tunnel environments
Authors: Sapena Joan , Dalmagne Clement
Published: December 2023

Acoustic comfort for modern rolling stock is a standard design requirement. The use of standard measurement conditions (ballast and free-field conditions) is the best way to identify quiet vehicles but operators (specially metro operators and some suburban) prefer to set noise targets
in their own infrastructure. Metro infrastructures are mainly today done with ballastless tracks either in elevated track (viaduct) or tunnels. Therefore it is critical for rolling stock suppliers to develop methodologies to simulate interior noise performances on those scenarios to be able
to propose design solutions and to control the risks. In this paper, the methodology used by Alstom to simulate interior noise in tunnels and viaduct is described. Methodology uses databases of acoustic transfer functions between sound power level of noise sources and acoustic wall pressures
around vehicles. These transfer functions are modified in function of the environment (viaduct or tunnel) taking into account the type of acoustic field. Then, analytical or numerical models of the train structure plus interiors are calculated. Simulation cases and validation of the models
are discussed to evaluate the pertinence of using virtual validation instead of interior noise type tests.
Experimental investigation of the effect of material on the non-linear properties of perforated plates
Authors: Khodashenas Niloofar Sayyad
Published: December 2023

Perforated plates are one of the effective passive noise controllers in the aeroacoustics system and industry. Effective absorption, resistant in harsh environment and easy maintenance are main reasons for perforated plates having several applications. Literature shows that even though
perforated plates are common sound absorbers, they can be relatively easy non-linear. There are many reasons for this, for instance, temperature, and high level sound pressure. High sound pressure level can have non-linear impact at fairly low levels. Therefore, identification and understanding
of this phenomenon is important. This is an essential reason for this study to experimentally investigate perforated plates with different material and study the non-linear properties of them. Two perforated plates with different material, fiberglass and steel, have been studied. The results
illustrate that the geometry such as perforation, its thickness and the perforated plate material affect the non-linear properties of the perforated plate.
Effect of leading edge and trailing edge serrations on a rotating Wells turbine
Authors: YASUI Hiroki , AKATANI Naoya , KURIHARA Eru , HAMAKAWA Hiromitsu
Published: December 2023

Wells turbine used for wave and wind power generation is known to generate loud noise during its operation. Aerodynamic noise reduction is an important issue in the design of the turbines. Since aerodynamic noise depends highly on behavior of the vortices around the turbine and the
flow structure in the wake region, understanding of behavior of the unsteady flow past a rotating turbine plays important role. In this study, we modeled Wells turbine with normal (solid) blades and serrated turbine. To visualize the flow separation and vortex generation near the rotating
turbine at its startup, LES simulations were performed by using moving mesh and transient inlet condition. In addition to the detailed flow structure around the turbine, the results show that the axial torque of the turbine increases with respect to the monotonically increasing inlet velocity.
It is also found that positive axial torque generated for the normal and trailing edge serrated turbines as the inlet flow velocity increased, but no torque was obtained for the leading edge serrated turbine due to flow separation at the leading edge.
Drone audition: improved Gaussian mixture model Wiener filtering approach for audio signal enhancement
Authors: Manamperi Wageesha N. , Abhayapala Thushara D. , Samarasinghe Prasanga N. , Zhang Jihui (Aimee)
Published: December 2023

Audio signal enhancement is an integral function of drone audition systems which emerges intelligent audio applications for military and civil environments. Signal enhancement using a drone is challenging due to its emission of significant noise from drone motors and propellers resulting
in an extremely low signal-to-drone noise ratio level. A method for signal enhancement from an on-board microphone array on a drone for static flight conditions in adverse noisy environments is proposed. In this paper, we present an improved Gaussian mixture model Wiener filter approach for
a noisy drone platform in the presence of interfering noise sources such as wind, and traffic. The key to this method is to exploit the spatial properties of the noise sources by using a set of Gaussian components to derive an accurate estimate of the power spectral densities of both residual
drone noise and interfering noise sources to obtain the enhanced target sound source signal. We demonstrate the method's general applicability for both speech, and bird calls using an extensive experimental study, including an experimental recording from a drone acoustics dataset using measured
impulse responses, and an outdoor measurement from a hovering drone for a bioacoustic application, respectively.
Improving the sound environment and preventing risky practices for youth
Authors: Rozec Valerie
Published: December 2023

Noise environment to which young children are subjected in their daily lives can be experienced as annoying and their listening practices with headphones are also increasingly early. During our noise prevention campaigns aimed at elementary school, a questionnaire is proposed before
the prevention session to find out their perception of sound environment and their listening practices in terms of headphones or earphones and a second questionnaire during the second session aims to evaluate the knowledge acquired during the first session and the prevention tools tested.
The aim is to better understand their perception of the sound environment in order to adapt prevention messages to their practices and to improve the quality of the sound environment of young children. The results (3541 pupils from second to fifth grade) show that young children suffer more
from noise at school and in their leisure time than their elders. listening practices which are hazardous for hearing increase with age. The prevention campaigns conducted by the CidB have taken these results into account and thus provide young students with appropriate recommendations for
improving the noise environment in the classroom and to protect themselves from high noise levels at leisure.
Influence of emitter's position in the field of view of the acoustic camera and ground reflection in sound source localization with beamforming
Authors: Fredianelli Luca , Pedrini Gregorio , Bernardini Marco , Bolognese Matteo , Licitra Gaetano
Published: December 2023

Acoustic cameras are powerful tools that combine a video camera with a microphone array to locate noise sources. Different beamforming techniques can be applied to the acquired sound signals, allowing to visualize noise or distinguish the contribution of multiple different sources even
emitting simultaneously. A procedure has been previously developed by the authors for the analytical analysis of the output images of the acoustic cameras. In fact, output images contain only visual information on the origin of the sound in the visual field of the camera, without providing
analytical information about their position. The procedure allows to quantify the localized position and also evaluate the distance from the real emission point when know, making possible comparison between different acoustic camera or different beamforming algorithms. In the present work,
the aforementioned procedure is applied to test measurements carried out with a known emitter in an open field to evaluate the effect that source's height from the ground and position in the field of view have in the localization with beamforming techniques.
Reverse design of involute helical gear pairs considering machining errors based on IMAGEWARE and HYPERMESH
Authors: Li Shanran , Zuo Shuguang , Liu Panxue , Li Huan
Published: December 2023

Gears inevitably contain errors during the manufacturing and installation process, which can increase the vibration and noise of the gear system. The finite element model with error can accurately solve the variation of vibration and noise and meshing characteristics of such gear systems.
This paper develops a combined analytical and simulation method for involute helical gears when machining errors are included. First, the tooth profile accurate point clouds of the involute gear are derived by cutting the tooth blank with the rack and the coordinate transformation function.
Subsequently, the gear is reconstructed by the IMAGEWARE and UG. With HYPERMESH's powerful node editing capabilities, sinusoidal profile errors can be assigned to gears. Also, the intersection of the error gear with the tooth blank is used to find the apex, which has an essential effect on
noise. Finally, the difference in static transmission errors of gears with and without errors is analyzed by ABAQUS. The results show that gears containing errors increase the peak-to-peak values of transmission errors, i.e., increasing noise. The method proposed in this paper can provide
a basis for modeling and analysis of meshing characteristics of special gears that cannot be directly parameterized or gears with various errors.
Outdoor engine test using acoustic liners combined with Fine-Perforated-Film
Authors: Murata Yo , Ishii Tatsuya , Enomoto Shunji , Oinuma Hideshi , Nagai Kenichiro , Oki Junichi , Kubo Gai , Daiguji Hirofumi
Published: December 2023

Resonant-type liner panels are one the primary countermeasures for the fan noise of aircraft engines, though the noise reduction performances of the liners are known to be tolerated by the flow streaming on the liner surface. Therefore, suppressing the effect of the flow on the liners
is greatly important for larger noise reduction. In this study, a liner panel with a special surface structure was manufactured and applied to an outdoor test using a small turbofan engine, DGEN 380. The surface structure consisted of a special thin film, Fine-Perforated-Film (FPF), and a
gap. The gap was fixed between the FPF and liner surface. In addition, a typical resonant-type liner and a hard wall were used for comparison, to investigate the effect of the structure. During the test, the samples were installed to the exhaust bypass duct of the DGEN 380 engine. The acoustic
pressure was measured with a far field microphone array. Analysis and comparison of the results showed that the new structure suppressed the effect of the grazing flow and caused a larger amount of noise reduction, compared to the typical liner sample.
Underwater target material classification based on feature extraction of finite element simulated signal
Authors: Wang Yiting , Han Ning
Published: December 2023

Feature extraction is crucial for underwater target classification and recognition, and this paper aims to propose a scheme for accurately classifying the material features of underwater targets. Finite element simulation software COMSOL is used to obtain echo signals, and then Auto
Regressive (AR) coefficient, cepstrum feature, spectral peak and its frequency of Smoothing Pseudo Wigner-Ville Distribution (SPWVD) of echo signals are extracted as the input of the pattern recognition network. The classification results show that the proposed scheme is able to effectively
differentiate among four types of materials: metal, brick, plastic and rubber. The scheme also shows good robustness for the target size and shape, and the proposed scheme has the potential to be applied to the practical underwater target classification.
An adaptive multichannel speech dereverberation approach based on robust estimation
Authors: Zeng Xiaojin , He Hongsen , Zhu Zhen
Published: December 2023

Room reverberation usually produces adverse influence on the quality of speech in human-machine interaction scenarios. To improve the clarity and intelligibility of reverberant speech, an adaptive multichannel speech dereverberation approach is proposed in this work. Unlike the traditional
least-squares cost function for speech dereverberation, a robust estimator with an adaptive parameter is adopted to define a flexible cost function of the adaptive speech dereverberation algorithm. As a consequence, the developed adaptive filtering algorithm can dynamically track the non-stationarity
and non-Gaussian properties of speech so that the reverberation component of speech is effectively suppressed. Numerical simulation experiments validate the dereverberation performance of the proposed approach.
The research of the acoustic perceptibility of silent electrified vehicles and acoustic vehicle alert system (AVAS)
Authors: Subbotkin Anton , Stepanyuk Alexey , Tyurin Alexandr , Maksimenko Timofei
Published: December 2023

The paper is devoted to the study of subjective acoustic perceptibility by pedestrians of silent electrified vehicles of various types moving at a constant speed, as well as ways to increase perceptibility using the Acoustic Vehicle Alert System (AVAS). The paper presents the results
of naturally (travel) measurements of subjective acoustic visibility.
A portable augmented/virtual reality auralisation tool for consumer-grade devices with companion desktop application
Authors: Beresford Tim , Wong Jack
Published: December 2023

Auralisation is the technique of presenting realistic acoustic scenarios to interested parties, through simulation using appropriately processed audio signals, without the need for the scenario to be physically constructed. Current state-of-the-art auralisations typically require a
dedicated listening room with very low reverberance, very low background noise, and a multi-channel loudspeaker setup. More recently, auralisations have been coupled with virtual reality (VR) visualisations to enhance the user experience, through use of VR head-sets. Recent computational power
increases in portable consumer-grade devices, such as smart phones and tablets, have meant that rendering a 3D augmented reality (AR) or VR simulation is now a possibility on such devices. The AR/VR auralisation application, AiHear, has been developed which utilizes the portable device platform
in conjunction with an off-the-shelf (calibrated) headphone setup to play back accurate auralisation audio. An Ai-Hear companion desktop application enables rapid creation and modification of auralisation scenarios, and allows the audio and visuals to be previewed before they are imported
onto the portable device. This paper looks at some of the technical aspects of successfully implementing an AR/VR auralisation application for use on a low-cost consumer-grade platform.
Survey of undesirable noises in an industrial clean room
Authors: Yamashita Daisuke , Harashima Kazuaki , Takeda Aoi , Sato Naru , Umayahara Hiromitsu , Nakaichi Takeshi , Higashikubo Ichiro
Published: December 2023

In industrial clean rooms, air conditioning systems and other necessary equipment are a constant source of noise. Out of the three clean rooms (X, Y, and Z) managed by us, Room X had particularly annoying noise levels, and required investigation. In this study, surveys are performed
to determine how the noise can be minimized: the facilities in each room are investigated, the working environment and personal noise exposure are measured, the noise sources are subjected to frequency analysis, and hearing tools are evaluated to reduce annoyance among clean-room users. The
measurement results show that the noise level in room X was more than 5 dB higher than that in rooms Y and Z. The frequency analysis results show that the dominant frequency spectrum of the fan filter unit (FFU) operating noise is around 100 Hz, and that of the air blowing noise is in the
high frequency range above 10 kHz. Finally, hearing tools (noise-canceling earphone and earplugs) are distributed to workers in Room X, who rank their effectiveness. The results show that noise-canceling earphones are preferred, although no statistically significant differences are obtained.
Consequently, the work environment is effectively improved.
Improving flow and noise performances of centrifugal pump in dishwasher through impeller design optimization
Authors: Song Younguk , Ryu Seo-Yoon , Cho Sung Dae , Cheong Cheolung , Kim Tae-hoon , Koo Junhyo
Published: December 2023

Noise and performance are critical factors in the customer's selection of dishwashers. The centrifugal pump, which circulates water for washing dishes, dominantly influences the performance and noise of a dishwasher. This study aims to improve the performance and reduce the noise of
a centrifugal pump by modifying its impeller design. Priorly, the flow and noise characteristics of the target pump were experimentally characterized. Then, the flow performance of the pump was predicted using a virtual pump performance tester based on the computational fluid dynamics techniques
to solve the three-dimensional unsteady incompressible Reynolds Averaged Navier-Stokes equations. The noise radiation generated by the impeller was predicted using the Ffowcs Williams-Hawkings equation. The results were validated by comparing the predicted with the measured. The Response Surface
Method, where the blade inlet and outlet angles at the hub and shroud locations were used as design variables, was applied to improve the flow and noise performance of the pump. The optimized impeller design increased the pump flow rate by 17.5% and reduced the flow noise level by 3.5 dB at
the same flow rate, as per the fan law predictions.
Subjective evaluation of source distance in dynamic 2.5D local sound field synthesis
Authors: Asano Takashi , Matsumoto Ryota , Ikeda Yusuke , Oikawa Yasuhiro
Published: December 2023

Many loudspeakers are required to reproduce the immersive and physically-accurate sound field up to high frequency. Especially, at high frequency, a limited number of loudspeakers degrade the reproduction accuracy because of spatial Nyquist frequency. When use the same number of loudspeakers,
reducing the extent of the reproduction region can improve the reproduction accuracy. However, by narrowing the reproduction region, the extent of movement for the listener is reduced. In our previous studies, we proposed the dynamic reproduction system of local sound field by moving the reproduction
region to the listener's current position. Using a limited number of loudspeakers, the proposed system achieved the sound reproduction with high accuracy allowing the freedom of listener movement. In this study, we conduct the subjective evaluation of the dynamic 2.5D local sound field synthesis
for sound source distance. Especially, we investigate the distance perception by allowing listeners to move around freely.
Sound field reproduction based on physical-model-based pressure matching with frequency-dependent variable control regions
Authors: Matsumoto Ryota , Tsunokuni Izumi , Suzuki Yukika , Ikeda Yusuke
Published: December 2023

The pressure matching (PM) method, one of the numerical sound field reproduction methods, requires the measurement of many transfer functions. Thus, it was difficult to modify the extent of the control region and the number of control points. In our previous studies, we proposed physical-model-based
PM method by using sparse equivalent sources. Since the sound field from each loudspeaker is modeled by the superposition of equivalent sources, we can obtain the transfer functions at any position from the loudspeaker. Thus, the density and extent of control points can be freely modified.
On the other hand, the PM method has the limitation that the reproduction accuracy depends on the extent of the controlled region. In this study, we proposed physical-model-based PM method with frequency-dependent variable control regions. In the simulation experiment, we evaluate the relationship
between the extent of the reproduction region and the reproduction accuracy at each frequency. We also discuss the total reproduction accuracy when the extent of the reproduction region is modified for each frequency.
Measurements of underwater noise genenrated during wind turbine operation in Korea Southwest Offshore Wind Farm
Authors: Yoon Young Geul , Han Dong-Gyun , Choi Jee Woong
Published: December 2023

Offshore wind power generation, a representative eco-friendly energy generation, is known as one of the promising solutions for sustainable development. However, the potential negative impact of underwater noise emitted from wind turbine operation on the marine ecosystem may limit development.
Measurements of underwater noise generated from the operation of a 3-MW offshore wind turbine in the Korea Southwest Offshore Wind Farm located off the southwest coast of Korea were made twice in late February to early March and November 2021, and the acoustic characteristics of operational
noise with wind speed, rotor speed, and tower vibration were investigated. As a result, the tonal frequencies of the underwater noise and tower vibration acceleration signal coincided, and their changes showed high correlations with the wind speed and rotor speed. Our results may be used as
a reference to evaluate the impact of underwater operational noise of offshore wind turbines on the marine environment.
Acoustic Metamaterial for Broadband Soundproofing and Ventilation
Authors: Lee Inho , Yoon Gwanho
Published: December 2023

Conventional materials for noise control are effective at absorbing and insulating sound waves, but they are often bulky and heavy. Acoustic metamaterials, on the other hand, can achieve similar level of noise control with maintaining more compact and lightweight structures. Acoustic
metamaterials are typically realized by embedding resonance structures or coiling up spaces. Herein, we present a labyrinthine acoustic metamaterial that induces phase differences for destructive interference. The designed structure consists of two regions: a central open area for normal wave
propagation and a surrounding labyrinthine area for wave propagation over longer distance with phase differences. This design exhibits the noise attenuation over a broad frequency range from 992 Hz to 1710 Hz with phase differences of 3.12 rad and -3.15 rad at the peak frequency. Hence, our
acoustic metamaterial enables to insulate the noise in the broadband frequency with the ventilation.
Line Spectrum Trajectory Detection Method of Underwater Acoustic Signal Based on Particle filter
Authors: Zhang Minjie , Luo Xinwei
Published: December 2023

Line spectrum detection is a significant task to detect, track, and classify weak target sources for passive sonar systems. In order to solve the problem of tracking time-varying frequency trajectories, a track-before-detect (TBD) algorithm based on the two-layer particle filter structure
is proposed. The detect layer deals with the potential tracks by maintaining a low-threshold dynamic detection grid, which is used to determine the birth, death, and false alarm of targets. The tracking layer utilizes the particle filter to compute the joint multitarget probability density
through a Bayesian framework. Simulation results show that the proposed algorithm can effectively detect and track time-varying frequency trajectories in a low signal-to-noise ratio situation, which has certain research and application value in weak signal detection.
Widespread area estimation of Shinkansen Superexpress Railway noise for noise mapping in Japan
Authors: Maruyama Naoya , Harada Kazunori , Sugahara Akiko , Hiraguri Yasuhiro , Yokoshima Shigenori
Published: December 2023

The Environmental Quality Standards for Shinkansen Superexpress Railway (SSR) Noise in Japan stipulate that the maximum noise level measured at a representative point 25 meters away from the railway track is used for evaluation, without any estimation of noise levels, such as road-traffic
noise evaluation for the Environmental Quality Standards for Noise in Japan. In this study, a noise estimation model being studied by the Ministry of Environment in Japan was referred and its accuracy was verified by comparing it with actual measurements. A trial estimation of the SSR noise
levels was conducted in the area along the SSR line in Osaka Prefecture, Japan. The estimated values were accurate to within a plus or minus 5 dB at 34 out of 56 receiver points when compared to the measured values. However, the accuracy was poor in areas near tunnel entrances and where multiple
reflections from noise barriers were present, which were not taken into account in the noise estimation model. The results of the widespread area estimation showed that the noise level variation within an area was significantly affected by the location of buildings in relation to the railway
tracks.
Mixed Reality visualization of sound field using the room impulse responses modeled by room geometry and physical model
Authors: Uchida Ayame , Tsunokuni Izumi , Ikeda Yusuke , Oikawa Yasuhiro
Published: December 2023

For room acoustic design and detecting noise problems, the sound field visualization is useful to understand sound propagation in a room. In our previous study, we proposed the Mixed Reality (MR) visualization system for steady sound field with mapping the three-dimensional sound intensities
measured by moving a microphone array. To visualize the transient sound field, time-synchronization of multi-point measurements is required. However, the measurement time for the transient sound field becomes significantly larger compared to the stationary sound field. In this study, we proposed
the Mixed Reality visualization of sound propagation based on sound field modeling. From smaller measured data, we estimate the transient sound field by spatial interpolation based on the equivalent sound sources and room shape acquired by Simultaneous Localization and Mapping. The estimation
results were visualized by MR technology using Microsoft HoloLens2.
Data-driven simulation for two-dimentional sound field considering room shape
Authors: Sato Gen , Ikeda Yusuke
Published: December 2023

Estimating the sound fields in a room using numerical simulations based on the wave equation typically requires extensive computation time. Consequently, several recent studies have explored the use of deep learning to reduce computation time. However, these studies have not adequately
accounted for differences in room shapes, which significantly affect reverberation. In this study, we propose a novel approach that utilizes sound field simulation results for deep learning training data to estimate the sound field in rooms of various shapes. Our target data were obtained
using the boundary element method, and we employed full-resolution residual networks as our deep learning models. Through our experiments, we evaluated the accuracy of our proposed method for sound field estimation as well as the computational time required.