bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of machine learning based algorithms for active noise control of machinary noise
Authors: Sharma Arvind Kumar , Puri Amrita
Published: December 2023

Machine learning is becoming a part of every field. After the discovery of deep learning, its application in various fields are increasing day by day. This paper presents a study of three machine learning based active noise control algorithms to reduce machinary noise. Three algorithms
studied in this work are: filtered-x backpropagation neural network (FxBPNN), radial basis function (RBF) and deep recurrent neural network (DRNN). Experimentally recorded noises of band saw, CNC and compressor are used in the simulation study. Two cases of primary path are considered: a)
linear path and b) nonlinear path, along with a linear secondary path. Performance of the three algorithms are evaluated based on steady state residual noise.
Overview of the acoustics and psychoacoustics of reverse alarms installed on moving vehicles
Authors: Nélisse Hugues , Giguère Christian , Laroche Chantal , Vaillancourt Véronique , Boutin Jérôme
Published: December 2023

Audible alarms are often used on mobile equipment to alert nearby workers of safety risks, in particular with reversing vehicles. A prompt reaction to the alert is required but depends on many technical factors (e.g., mounting location on vehicle), acoustic factors (e.g., alarm emission
level, sound propagation pattern behind the vehicle) and psychoacoustic factors (e.g., perceived urgency, ability to localize alarm, effect of hearing loss and hearing protection). These factors are not fully addressed in applicable regulations or standards. This paper presents an overview
of the main results of a series of research studies carried out as a collaborative effort by the "Institut de recherche Robert-Sauvé en santé et sécurité du travail" in Montreal and the University of Ottawa in the past twelve years. A main objective was
to compare the relative benefits of two types of alarm signals, the widely-used conventional tonal signal and the relatively recent, but emerging, broadband signal. Overall, results indicate that the broadband alarm presents some benefits such as more uniform acoustic propagation patterns,
lower alarm reaction thresholds and better sound localization compared to the tonal alarm. The latter two advantages are emphasized when hearing protectors are worn.
On the test method for short-term level fluctuation of sound calibrators
Authors: Wu Lixue , Koukoulas Triantafillos
Published: December 2023

Most noise bylaws state that a precision sound level meter which meets the International Electrotechnical Commission Publication 651 or the American National Standards Institute S1.4-1983 needs to be used for noise measurements. To ensure measurement accuracy, sound calibrators are
used to check the sound level meter accuracy before and after any such measurements, as required by most noise regulations. The sound calibrator itself needs to be calibrated routinely and traceable to national standards. The International Standard IEC 60942, Electroacoustics - Sound calibrators,
specifies performance requirements for the sound pressure level, short-term level fluctuation, frequency, and distortion and associated test methods. However, the test method for short-term level fluctuation specified in IEC 60942 is problematic. The short-term level fluctuation cannot be
measured in some cases using the method specified in IEC 60942. In this paper, a detailed theoretical analysis is presented addressing this particular issue. Closed-form solutions are obtained for typical sinusoidal sound signals. Two experimental setups and measurement results for the validation
of the theoretical analysis are also presented. One uses a commercial sound level meter and the other uses a precision sound pressure measurement system developed recently at the National Research Council Canada.
Experimental investigation of the effect of absorption material on the non-linear properties of perforated plates
Authors: Khodashenas Niloofar Sayyad
Published: December 2023

Combinations of perforated plate and porous material are used in numerous applications for noise reduction at high sound pressure level, such as in aircraft engines and automotive mufflers. Therefore, it is important to have a better understanding of the acoustic property of these systems.
A semi-empirical model is a common way to calculate and understand the sound absorption of these systems. Previous studies show that the interface between a perforated plate and porous material have direct effect on the non-linear property of the perforated plate and sound absorption. Therefore,
in this study two conditions of perforated plate and porous material combinations was considered. First, when the perforated plate has direct contact to the porous material and second, when there is air gap between them. Results of this research shows that the variation of non-linear acoustic
resistance in case either with or without a cavity gap of air is relatively small.
Investigation on the comparison analysis of the characteristics between the Forward and Backward curved fan system and the Improvement on flow/noise performances by optimizing blade angles in clothes dryers
Authors: Choi Jinho , Choi Wonick , Jang Jinman , Chung Bosun , Kim Youngsoo
Published: December 2023

Recently, the needs for clothes dryers are rapidly increasing due to the consumer's interest in convenience for time reducing and cleanliness like dust. The drying performance of these clothes dryers is greatly affected by the fan system. The fan system affects the flow performance
and is related to drying time of clothes dryer. Also, the aerodynamic noise generated by the fan system in the dryer has a great influence on the overall noise of the machine. Because of these reasons, many manufacturers are conducting researches on improving the performance of the fan system
in the dryers. The purpose of this study is to improve the flow & noise performance of a fan system in clothes dryer using CFD (Computational Fluid Dynamics) and acoustic analogy based on FW-H (Ffowcs-Williams and Hawkings) equation. The numerical analysis on the flow characteristics of
the fan system is conducted by ANSYS FLUENT. The 3-dimesnsional incompressible RANS (Reynolds Averaged Navier-Stokes) equation is adopted as the governing equation and the SST k-ω model is used for turbulent model. The integral surface for FW-H equation to analyze the acoustic field
is composed of the closed surfaces including the scroll. This study investigates more suitable fan for a dryer system by comparing the flow characteristics of a backward curved fan, already adopted to a dryer, with a new forward curved fan which has same diameter. To improve the flow performance,
the blade angles have been tuned by the design optimization which is the response surface method for geometric parameters. As a result, the dryer with the forward curved fan, which had optimal blade angles, reduced the rotating speed with the same volume flow rate as the original fan. And
finally it showed the much reduced noise level compared to the original fan when the dryer ran.
Noise-aware UAS flight path planning based on virtual flight simulation
Authors: Tan Qichen , Bao Hongsen , Zhou Peng , Zhang Xin , Lo Hong Kam , Zhong Siyang
Published: December 2023

This paper proposes a noise-aware flight path planning method to reduce the noise pollution caused by low-altitude flights of unmanned aerial systems (UAS) in urban areas. A noise assessment platform is used to obtain noise maps at discretized airspace blocks, considering sound reflection
and absorption by obstacles, as well as diffraction and attenuation by the atmosphere. An improved cost-based A* algorithm is employed to search for the optimal path with the minimum sound exposure level. Virtual flight simulations demonstrate the effectiveness of the proposed method in reducing
en-route noise exposure from flying drones. This cost-effective and efficient approach has the potential to benefit air traffic planning and management.
Verification of simplified underwater radiated noise estimation tool using Brown's formula
Authors: Shiraishi Koichiro , Kume Kenichi , Arakawa Daijiro , Kamiirisa Hikaru
Published: December 2023

In recent years, the impact of underwater radiated noise from ships on marine life has attracted considerable global attention. Therefore, various research institutions are investigating this phenomenon through research and development efforts. In this study, authors have developed
an underwater radiated noise estimation tool that can be used in the early stages of ship design. This tool calculates the underwater radiated noise level by applying Brown's formula, a simple estimation formula for predicting the noise generated by ships. The parameters required for Brown's
formula are estimated using HOPE Light, a ship performance estimation software developed by the National Maritime Research Institute. The extent of cavitation is estimated using Burrill's diagram, a tool for assessing the occurrence of cavitation. The accuracy of the developed tool has been
verified by comparing its results with full scale measurements of underwater radiated noise levels obtained off-board hydrophone array system.
Optimum design of TMDs for reduction of floor vibration using evolutionary computation
Authors: Araki Yozo , Taguchi Norio , Masuda Kiyoshi
Published: December 2023

Perceptible floor vibration can arise due to human activities such as walking, especially in steel-framed buildings. A general strategy to reduce floor vibration is to install tuned mass dampers (TMDs) between the floor slab and a raised OA floor. For the TMDs to act effectively, two
parameters must be designed properly depending on the dynamic characteristics of the target floor: eigenfrequency and damping ratio. Conventionally, even when installing multiple TMDs in a floor, design has been carried out using fixed-point theory, which was originally used to design a single
TMD. With the purpose of improving the performance of multiple-TMD installations, this paper describes the use of evolutionary computation (EC), a mathematical optimization method, to design the parameters for multiple TMDs. The new technique is first verified by implementing a numerical simulation
using the spectral element method, a high-efficiency numerical analysis method. TMDs designed with EC are shown to suppress floor vibration more efficiently than those designed with fixed-point theory. Next, in experiments with an actual steel-framed building, sufficient vibration suppression
performance is achieved with fewer EC-designed TMDs.
Optimal design for a perforated panel absorber combined with Helmholtz-resonance and plate vibration
Authors: Fujimoto Nozomu , Sanada Akira , Takata Suguru
Published: December 2023

This study proposes a perforated panel sound absorber combined with Helmholtz-resonance and plate vibration and its optimal design method to broaden the sound absorption characteristics. The proposed perforated absorber has a simple structure consisting of a flexible panel with a hole
and an air cavity. The conventional optimal design theory of the dynamic vibration absorber is applied to the perforated absorber. The proposed absorber is designed so that the acoustic impedance density will be equalized and almost minimized at two points independently of the damping of the
panel. Optimal parameters are related to the Helmholtz-resonance frequency, the natural frequency of the panel, and the loss factor of the panel. The absorber with the optimal parameters was fabricated, and the sound absorption coefficient was measured using an acoustic impedance tube. The
experimental results shows that the proposed method can effectively design the perforated panel absorber with the broadband sound absorption characteristics.
Review of strategies for mitigation countermeasures of aircraft noise in Japan and current issues
Authors: SHINOHARA Naoaki
Published: December 2023

In Japan, systematic countermeasures against aircraft noise have already been implemented since the 1970s. It is also in accordance with the later ICAO Balanced Approach. The measures could be divided into three main categories, which are reducing of noise source, Improvement of airport
structure and facility, and countermeasures for remedial compensation. The priority strategies were placed on introduction of low-noise aircraft, restrictions on night flights, construction of offshore airports, and remedial compensation such as soundproofing for houses etc. As a result, by
the 1990s, compensation measures for severe noise were completed, and nighttime flight restrictions prevented health effects resulting from sleep disturbance. However, since the beginning of the 2000s, residents' acceptance of aircraft noise has changed, and issues have appeared regarding
not so loud noise at locations far from airports. In addition, some airports are expanding late-night operations to meet the recent growth in aviation demand. This paper describes the review of strategies of mitigation countermeasures for aircraft noise in Japan and current issues such as
the new phase for making coexisting with surrounding residence area in currently, and the need for strategies.
Uncertain sound transmission loss of composite laminated plates with embedded viscoelastic damping layer
Authors: Zhu Xiaosong , Dong Ningjuan , Jiao Lijuan , Zheng Hui
Published: December 2023

Laminated composite structures have been widely applied in the engineering field due to their excellent capacities such as high specific stiffness, high specific strengths and tailorable anisotropic elastic properties. Embedding the viscoelastic damping layers into the laminated composites
to construct co-cured composite damping structures provides an effective way to improve the sound insulation capability. In this paper, a semi-analytical model is proposed to investigate the sound transmission loss (STL) of composite laminated structure with embedded viscoelastic damping layer
considering its frequency-dependent characteristic. Furthermore, Polynomial Chaos Expansion (PCE) method in conjunction with the semi-analytical model is employed for uncertainty propagation analysis of sound transmission loss of the composite laminated plates subjected to uncertain parameters
of frequency-dependent interleaved viscoelastic damping layer. Moreover, numerical simulations are conducted to demonstrate the impacts of the uncertain parameters of the embedded viscoelastic damping layer on the STL of the composite laminated plate. Finally, experiments are carried out to
investigate the uncertain acoustic insulation performance of composite laminated plates with embedded damping layer. Key words: Laminated composite structure; Sound transmission loss; Uncertainty analysis; Damping layer; Frequency-dependent properties
Subjective Response Test of Auralized Brushless Direct Current Motor-Propeller System Noise
Authors: Jeong Jaeheon , Ko Jeongwoo , Lee Wonhee , Lee Soogab
Published: December 2023

The auralization can be an effective asset in the design of unmanned aerial vehicles (UAV) and urban air mobility vehicles, serving as a valuable resource in decision-making regarding the mitigation of noise-related issues. However, in order to be effective, the auralization must be
perceptually accurate. During the process of auralization, a multirotor noise evaluation framework based on multidisciplinary principles was employed to model the periodical fluctuations in rotational speed. The subjective response test was utilized to evaluate synthesized UAV-like noise.
The tests included participants becoming acquainted with different noise sources (ice-breaking), assessing participants' emotional responses to different noises (helicopter and UAV-like), and evaluating participants' ability to differentiate between measured and auralized sounds. Statistical
analysis of the results of the subjective response test showed that the measured noise and the auralized noise were not identical, but were not perfectly indistinguishable. These results demonstrate the effectiveness of psychoacoustic methods and statistical analysis in the perceptual assessment
of noise and validate a comprehensive rotor noise assessment framework based on a multidisciplinary approach.
A Deep Learning Approach to Optimize Airfoil Shape for Reduced Trailing Edge Noise in Urban Air Mobility Rotors
Authors: Lee Wonhee , Lee Soogab
Published: December 2023

The objective of this research is to optimize the airfoil shape of UAM VTOL rotors for trailing edge noise reduction. Our study focuses on employing deep learning techniques for airfoil shape optimization with an emphasis on noise reduction. We implement a neural network that combines
a Variational Autoencoder and Generative Adversarial Networks to learn the representation of airfoil shapes. The generated airfoil shapes are then evaluated for aerodynamic performance using XFOIL and trailing edge noise using acoustic diffraction model. The optimization process employs a
Particle Swarm Optimization algorithm to find optimal latent features for airfoil generation. The results show that the optimized airfoil shapes have improved aerodynamic performance and reduced noise levels compared to the airfoil VR-12 used in NASA's conceptual UAM. These findings demonstrate
that our optimization process has the potential to reduce trailing edge noise while ensuring enhanced aerodynamic performance, which warrants further investigation.
Subjective evaluation test on the effect of tonal components on broadband noise
Authors: Yonemura Miki , Sakamoto Shinichi
Published: December 2023

Environmental noise sometimes contains tonal components, and it has been pointed out that this can be responsible for increasing the annoyance of noise. In Japan, noise problems related to tonal noises generated from wind turbines and heat pump systems have recently been occurring.
To solve the noise problem, it is necessary to quantitatively understand the effect of tonal components on noise annoyance. In this study, annoyance evaluation experiments were conducted using broadband noise containing a tonal component. Four types of noise were used for the auditory test:
white noise, pink noise, and low-frequency prominent noise that simulated indoor- and outdoor environmental noise. The frequencies of tonal components added to the broadband noise were from 50 to 2000 Hz, with intensities where the tonal audibility was 0, 5, 10, and 15 dB. The results show
that the annoyance increases with the intensity of the tonal component, but the amount of increase depends on the frequency characteristics of the background noise and the tonal frequency. This increase in annoyance was quantified as a penalty in A-weighted sound pressure level.
Modeling and reproduction of sound field by moving complex sound source
Authors: Sasaki Yo
Published: December 2023

Previously, Wave Field Synthesis (WFS), Near-field Compensated Higher-Order Ambisonics (NFC-HOA), Boundary Surface Control (BoSC), and the Spectral Division Method (SDM) have been proposed as sound field synthesis methods. These methods are based on matching the acoustic physical quantities
at the boundary of the reproduced sound field with those of the desired sound field. Sound field synthesis techniques can be classified into data-based and model-based methods. The former aim at reproducing sound fields captured by microphone arrays, while the latter aim at synthesizing sound
fields based on mathematical models. Most existing sound field reproduction methods only consider simple sound source models, such as static point sources, instead of sound sources with complex radiation properties. To generate a more realistic sound image, this study investigated the formulation
of a sound field generated by a sound source with complex radiation properties moving along arbitrary trajectories in a spherical harmonic domain, and reproduced the sound field using loudspeaker arrays.
Free vibration analysis of corrugated plate based on improved Fourier series method
Authors: Meng Hongbo , Zhang Runze , Zhang Shanyue , Cao Yipeng
Published: December 2023

Corrugated plates are widely used in ships, underwater vehicles and other engineering fields due to their good bending stiffness and strength characteristics. The properties of corrugated plates are determined by their corrugated shape, wavelength, and wave height, which affect each
direction differently. In order to model these properties quickly and accurately, this paper employs an improved Fourier series method. The method is based on the Kirchhoff plate theory and equivalent stiffness method, expanding the displacement of the corrugated plate using Fourier series.
By applying the energy principle, the free vibration characteristics of the corrugated plate can be determined. This approach allows for efficient and comprehensive multi-parameter control modeling of corrugated plates. The influence of structural form, material parameters and convergence
on the vibration characteristics of corrugated plate is analyzed. This paper lays a foundation for the subsequent dynamic study of sandwich corrugated plate structure.
Engine Knocking Detection using Time-varying Specific Loudness and Microphone Array
Authors: Nakajima Yasutaka , Yasaka Takamitsu , Nishidome Chiaki , Mouri Etsunori , Shinohara Kenjiro
Published: December 2023

In the evaluation of internal-combustion engine knocking, the overall knocking level, such as no problem, slight, and obvious, is evaluated by a skilled person using auditory sense based on the knocking frequency of how often it occurs and the degree of knocking. In this study, we developed
a method to detect knocking based on both the steep rise using derivatives and the level of non-stationary specific loudness of radiated sound. Additionally, by using a microphone array, we aimed to improve the detection accuracy that is dependent on the location of knocking and microphone
position. Through experimental verification, we will compare the knocking level, which is the result of auditory evaluation by skilled listeners, with the knocking detection frequency of this method to validate the detection accuracy.
Effect of micro-slit entries on the sound absorption and size of a labyrinthine acoustic metamaterial
Authors: Pavan Golakoti , Singh Sneha
Published: December 2023

Low frequency noise attenuation is a pressing issue in the field of acoustics and noise control. In this regard, labyrinthine acoustic metamaterials have shown high potential in achieving low frequency sound absorption. This paper presents two new acoustic metamaterial designs consisting
of a labyrinthine of sub-wavelength straight folded air channels with a rectangular cross-section surrounded by sound hard boundaries, combined with a micro-perforated slit panel. Design 1 has two micro-slits at the end channels, whose lengths are the same as the width of labyrinthine channels.
Design 2 has two micro-slits of unequal length at the end channels. A simulation study using COMSOL Multiphysics is conducted to check the effect of the slit lengths on the sound absorption of these metamaterials. It is found that having micro-slits with unequal lengths for sound wave entry
leads to a higher absorption peak and a lower peak absorption frequency compared to that of micro-slits with equal lengths. Moreover, it leads to a better sound absorption performance with increasing thickness. The experimental results of the sound absorption coefficient are in good agreement
with the simulation results. Thus, Design 2 can be used for extremely low frequency sound absorptions in machinery with space constraints.
Vibration Control of a Multi-Disc Rotor System with Active Lateral Bearings and Disturbance Estimation
Authors: Ran Liaoyuan , Halim Dunant , Thein Chung Ket , Galea Michael
Published: December 2023

A rotor system used in a wide range of engineering applications generally consists of a rotor shaft, multiple discs, blades and other essential components, generating a multi-disc rotor arrangement. System uncertainties caused by unbalanced discs and disc mass variation, compounded
with external disturbances under different operating conditions, can lead to a variation in rotor-dynamic characteristics with multiple structural resonances, potentially causing an excessive level of rotor lateral vibration. Therefore, to effectively suppress lateral vibration for such a
multi-disc rotor system, an active vibration control approach using active lateral bearings with disturbance estimation is presented in this work. The utilized active lateral bearings can generate necessary bearing displacement regulations to eliminate the bearing forces so to effectively
control the lateral vibration of the rotor system. The disturbance estimation approach is used to estimate the unknown uncertainties associated with the system's internal dynamics and external disturbances affecting the rotor system, incorporating an extended state observer (ESO). Utilizing
the total disturbance estimated by the ESO to cancel out the effects of the disturbance using active lateral bearings, the rotor lateral vibration can be satisfactorily suppressed with sufficient control robustness against uncertainties in the rotor internal dynamics, particularly associated
with the degree of mass unbalance of rotor discs, demonstrating the effectiveness of the active vibration control approach for suppressing vibration in a rotor system.
Direction-of-arrival estimation of impulse noise using MUSIC algorithm
Authors: Asai Takuro , Masuda Kiyoshi
Published: December 2023

Spatial information about the source of sounds can be obtained by measuring amplitude and phase differences among multiple microphones in a microphone array. Various methods have been proposed for estimating the direction of arrival, including beam-forming methods, but generally their
spatial spectral resolution degrades with a low-frequency source in the far-field. In architectural acoustics, it is important to obtain high spatial resolution in the low-frequency band, especially in investigations to understand phenomena such as sudden impulse noise. In this paper, direction-of-arrival
estimation using the MUltiple SIgnal Classification (MUSIC) method is discussed. We propose a microphone array structure designed according to the Cramer-Rao lower limit. It is shown that this technique improves the accuracy of elevation angle estimates at low frequencies while maintaining
good horizontal angle estimation accuracy. The proposed method was tested in a real building in which impulse noise occurred and its effectiveness in identifying the source direction with high spatial resolution even at low frequencies was confirmed.
Snapping shrimp noise detection methods based on linear prediction analysis
Authors: Park Soo Hyun , Park Jinuk , Hong Jungpyo
Published: December 2023

This paper proposes features for detecting snapping shrimp noise based on linear predictive analysis. Snapping shrimps are a species inhabiting the ocean depths and are one of the main sources of underwater noise due to their high-amplitude signals that occur frequently. The proposed
features utilize the characteristic of sudden onset and rapid decay of pistol shrimp noise by using linear predictive analysis to accurately detect the noise segments and mitigate the impact of snapping shrimp noise. The large error between the predicted values by linear predictive analysis
and the actual measured values allows for effective detection of pistol shrimp segments. Additionally, the proposed features are combined with a fixed-threshold detector to further improve the performance of noise segment detection. When compared to the state-of-the-art method known as multilayer
wavelet packet decomposition, the proposed method outperformed with an average improvement of 0.12 in terms of receiver operating characteristic curve and area under the curve. Moreover, the proposed method had lower computational complexity.
Application of Active Impulsive Noise Control (AINC) for Excavator Cabin Using Advanced Convex-Combined Normalized step size Algorithm and Verification of Robustness
Authors: Lee Donghyeon , Kim Narae , Jang Yeonjin , Jang Yeonjin , Park Junhong
Published: December 2023

Conventional Active Noise Control (ANC) algorithms, such as Filtered-x least mean square (FxLMS), is not suitable for Active Impulse Noise Control (AINC). Because it lacks robustness to the impulsive sample input, it is unstable and diverges very easily. Therefore, AINC algorithm must
be robust to impulse. The heavy equipment such as excavators often occur frequent impulse noise during operations. Also, in working environment of operating excavator, impulsive noise is prone to occurred by other heavy equipment. Therefore, it is necessary to examine the AINC algorithm that
is suitable for excavators and its robustness. In this study, Convex Combined Step Size (CCSS), which is simulated better effects in AINC than conventional ANC algorithms, is tried to AINC of excavator. In addition, the noise reduction performance and robustness to undesirable sound were verified
in the simulated experiment environment of the excavator cabin.
Ultrasound focusing enhancement through the stiff plate with inversely optimized metamaterial lens
Authors: Gao He
Published: December 2023

Conventional ultrasound focusing implementations generally rely on steering the transmitted ultrasound wave through the openings in the designed lenses, which are ineffective for ultrasound focusing through a plate without openings. Here, we have proposed an inverse optimization scheme
to fabricate a metamaterial lens that can enhance ultrasound focusing through a stiff plate immersed in water without any openings. This metamaterial lens can enhance the power transmission, and at the same time focus the transmitted power well. The optimized acoustic focusing enhancement
lens shows great potential in medical imaging and disease treatment.
Enhance signal of underwater locator beacon by adaptive filter and simulation received signal
Authors: Hung Ching-Tang , Wu Chao-Jung , Peng Chiao-Ming , Lai Jian-Wu , Chuang Li-Chang , Yang Wen-Rong , Chen Chi-Fang
Published: December 2023

Searching for and recovering a flight recorder at sea is a complex and demanding task. Once the flight recorder is submerged, the underwater locator beacon (ULB) mounted on it will activate. In this study, we developed an algorithm combining an adaptive filter and a simulated received
signal to enhance the signal-to-noise ratio (SNR), thereby increasing the probability of detecting the ULB signal. The experiment was taken place off the coast of Kaohsiung, Taiwan, with a ship towing an array and circling a prepositioned ULB to collect underwater acoustic data. The ULB signal
was significantly amplified using the proposed algorithm. This research offers a pre-processing technique for ULB signal enhancement, demonstrating its applicability in real-world scenarios.
Active Noise Control in The New Century: The Role and Prospect of Signal Processing
Authors: Shi Dongyuan , Lam Bhan , Gan Woon-Seng , Cheer Jordan , Elliott Stepehen J.
Published: December 2023

Since Paul Leug's 1933 patent application for a system for the active control of sound, the field of active noise control (ANC) has not flourished until the advent of digital signal processors forty years ago. Early theoretical advancements in digital signal processing and processors
laid the groundwork for the phenomenal growth of the field, particularly over the past quarter-century. The widespread commercial success of ANC in aircraft cabins, automobile cabins, and headsets demonstrates the immeasurable public health and economic benefits of ANC. This article continues
where Elliott and Nelson's 1993 Signal Processing Magazine article [1] and Elliott's 1997 50th anniversary commentary [2] on ANC left off, tracing the technical developments and applications in ANC spurred by the seminal texts of Nelson and Elliott (1991), Kuo and Morgan (1996), Hansen and
Snyder (1996), and Elliott (2001) since the turn of the century. This article focuses on technical developments pertaining to real-world implementations, such as improving algorithmic convergence, reducing system latency, and extending control to non-stationary and/or broadband noise, as well
as the commercial transition challenges from analog to digital ANC systems. Finally, open issues and the future of ANC in the era of artificial intelligence are discussed.
Aeroacoustic measurements of a contra-rotating UAV vehicle
Authors: Pereira Lourenco Tercio Lima , Puroja Brian , Zamponi Riccardo , Rosa Ilaria , Ragni Daniele
Published: December 2023

The aerodynamic sound linked to the increasing presence of Unmanned Aerial Vehicles (UAVs) is becoming a societal concern. Assessing the aeroacoustics of these vehicles is of utmost importance, as it enables the evaluation and mitigation of the associated noise emissions. An experimental
wind-tunnel investigation is carried out with an octo-quad multi-rotor model UAV with 4 sets of contra-rotating propellers, representative of a heavy-lifting drone, to assess the acoustic emissions of the vehicle under different flow and thrust conditions. The experiments are performed in
the Open Jet Facility of the Delft University of Technology. The acoustic measurements from several microphones are combined to create the noise signature of the UAV, while the data from a balance are processed to compute the thrust. The results of this research demonstrate that it is possible
to reduce the noise emissions of the drone by varying the operating input between the fore and aft motors. In particular, an attenuation in the overall sound pressure level of 5 to 8 dBA can be achieved if the RPM of the fore motors is decreased while that of the aft motors is increased.
Multi-channel active noise reduction system realizes the local area sound field control of the subway driver's cabin
Authors: Peng An , Zhang Xiaojie , Wu Hengliang , Li Xiaohu , Yin Ziyu , Tong Zongpeng
Published: December 2023

Aerodynamic noise, air conditioning fan noise, and wheel-rail noise during subway operation have an adverse effect on drivers' physical and emotional well-being and can jeopardize the safe operation of vehicles. On the basis of the original passive acoustic treatment, multi-channel
active control technology is used to manage the local sound field in order to further enhance the acoustic comfort of subway drivers' working environment. The multi-channel active noise reduction system installed on the driver's seat is described in this paper. In order to properly prevent
the issues of ear pain and obstruction brought on by prolonged use of noise-canceling headphones, the system integrates reference sensors, error sensors, speakers, and a power amplifier within the headrest. The noise in the carriage is picked up using a multi-channel reference signal, and
a low delay and anti-interference algorithm is investigated in accordance with the wide frequency band's characteristics and the abrupt change in sound pressure level when the vehicle is running. The test results demonstrate the system's ability to stabilize under situations of abrupt changes
in driving noise and in-car broadcast, as well as to successfully minimize noise in the head area of subway drivers.
Acoustic Performance and Lifecycle Assessment of Common Building Materials: A Comparative Case Analysis
Authors: Kotyck David , Ng Alex Ho Ting , Chan Henry Chi-Kee , Ng William Chi-Wing
Published: December 2023

Motivated by the Hong Kong Climate Action Plan 2050, a lifecycle case analysis assessment of various typical construction materials often proposed for acoustic purposes has been performed. The findings have been analysed and a metric has been explored which assesses a material's combined
value based on its sound insulation ability and carbon emissions produced by its use in a project.
Evaluating the effect of masks on the vocal health and speech intelligibility of healthcare workers in various hospital unit
Authors: Oktavi Khairini , Sarwono Sugeng Joko , Nitidara Ni putu amanda , Sudarsono Anugrah Sabdono , Hidayah Nurul , Ziwei P.J. Lee dan S. , Selintung Gladys Thenny
Published: December 2023

The COVID-19 pandemic has enforced mandatory mask usage, particularly in hospitals, and its impact on the vocal problems and speech intelligibility of healthcare workers was examined in this study. A total of 76 healthcare workers from various units, including emergency, inpatient,
outpatient, and intensive care, participated in an online questionnaire survey to assess vocal issues experienced while wearing masks. The participants' self-assessed vocal handicaps were quantified using the Vocal Handicap Index (VHI) score. The findings revealed that healthcare workers in
emergency units faced the most severe vocal problems, followed by those in outpatient units. The most reported vocal symptoms were clearing the throat and throat dryness. Additionally, noise levels were measured continuously for four hours in each unit, and sources of noise were identified.
The measured sound pressure levels (SPL) in emergency, inpatient, outpatient, and intensive care units were 68.64, 63, and 72 dBA, respectively. These values exceeded the World Health Organization's recommended limit of 30-40 dBA, indicating significant discomfort. Lastly, to delve deeper
into the increased vocal effort required when wearing masks, the Speech Transmission Index (STI) parameter was analyzed using the recorded SPL as background noise and audio recordings of healthcare workers in different mask-wearing conditions. The study discovered that using a mask considerably
reduced speech intelligibility compared to not wearing a mask. Keyword: healthcare workers, vocal problems, noise level, pandemic
Effects of size and hardness of pinna on cartilage conduction hearing: Comparison between auricular hematoma and normal subjects
Authors: Tamura Akane , Irwansyah  , Otsuka Sho , Nakagawa Seiji
Published: December 2023

Bone conduction (BC) is a method of perceiving sound via biological tissue by presenting a vibrator to the skull. BC has been applied to hearing aids for the conductive hearing loss and earphones which can be used even in noisy environments. However, a vibrator needs to be pressed strongly
in BC and this causes discomfort and pain. Therefore, cartilage conduction (CC), in which a vibrator is presented onto the auricle cartilage instead of the skull, has been proposed to solve these problems and actually applied to smartphones and hearing aids. However, influence of the properties
of the auricle itself on CC is still being studied. In this paper, we measured the auricle hardness, size, and thresholds of CC in patients with auricular hematoma and normal ear-shape subjects. We compared results with between these two subjects' groups and investigated relationships between
hardness and size of the auricle and thresholds of CC. Our results indicate that subjects with auricular hematoma have different perceptual characteristics compared to the normal-ear group and that the auricle hardness and size affect thresholds of the cartilage conduction.
A questionnaire survey on the prevalence of self-reported voice disorders in school teachers, and classroom noise in Japan
Authors: Evans Naoko , Kaneko Miki , Shigematsu Taiki , Sakamoto Hirokazu , Kiyono Ken
Published: December 2023

School teachers are known as professional voice users, hence any damage to their voice or throat could compromise their work as well as their lives. We conducted a questionnaire survey of 830 teachers working at elementary schools, junior-high schools, high schools and schools for children
with special needs in Saitama prefecture in Japan. We investigated the prevalence of self-reported voice disorders in teachers and how their quality of life might be influenced. We also asked the teachers to share some of their experience with noise in classrooms. We found the following three
points. Firstly, more than a quarter have consulted medical doctors for problems with their voice or throat. Secondly, quality of life of female teachers are slightly more affected by their voice problems than their male peers. Thirdly, approximately 20 percent of teachers are concerned about
the noise in their classrooms.
Effect of masker selection schemes on the perceived affective quality of soundscapes: A pilot study
Authors: Ong Zhen-Ting , Ooi Kenneth , Lam Bhan , Wong Trevor , Gan Woon-Seng , Watcharasupat Karn N.
Published: December 2023

The perceived quality of a given soundscape may be improved by adding "pleasant" sounds via a speaker or electroacoustic system to the existing soundscape as maskers. Ideally, the choice of sounds should be automated to minimize the time and labor required to maintain such
a system. Hence, we investigate the effect of several automated masker selection schemes on improving the ISO Pleasantness of urban soundscapes in a controlled laboratory environment. An ambisonic recording and 360-degree video of a location exposed to traffic noise was made and reproduced
via a stacked planar speaker array and virtual reality headset. Simultaneously, maskers from a fixed candidate pool were overlaid on the reproduced soundscape in one of the following methods: random selection across the entire pool, fixed selection based on results in the literature, random
selection across a restricted pool based on model-agnostic analysis of a pre-existing dataset, and random selection across a restricted pool based on a deep neural network trained on a pre-existing dataset. We also investigated a control condition with no added maskers, and evaluated the results
based on changes in ISO Pleasantness ratings given by participants to the soundscape under each masker selection scheme, relative to the control condition.
Soundscape conservation policy focusing on the active listening: An examination based on the case of the Enshu-nada Sea of Japan
Authors: Minoura Kazuya , Daimon Shinya , Kaneko Katsushi
Published: December 2023

This study examines the active nature of listening from the perspective of soundscape conservation. The classical psychophysics views hearing as a passive process, with a stimulus-response relationship. And the ISO definition of soundscape basically follows this scheme. However, this
study highlights the significance of active listening, where the listener intentionally seeks information from the sonic environment. In the Enshu region of Japan, which is the case of this research, there is a phenomenon that the sound of waves propagates far and wide, and this knowledge
has been passed down through generations tales and folklore. This fact indicates that the people in this region once had a culture in which they actively sought meaning from the sound of waves. In this study, we collaborated with local residents to conduct observations of wave sounds, and
some of the collaborators attempted to reconstruct their relationship with wave sounds through the practice of observation. The findings suggest that the act of listening has a significant impact on the formation of context. Therefore, active listening should be considered in soundscape conservation,
as well as its relevance to the definition of "context" in the ISO.
Exploring the public perception of sound of medical delivery drones in Scotland. An online listening test approach
Authors: Thomas Adam , Hiller David , Maldonado Ana Luisa , McLeod Laura , Sharp Calum , Woodcock James
Published: December 2023

Drones are a relatively new technology which has the potential to improve delivery times and reduce the carbon footprint of distribution networks. The transportation of urgent medical supplies is an example of a positive community impact of this technology, particularly to remote and
island locations that currently rely on slow and inefficient road transport and connecting ferry ports or traditional aviation. There is limited data available on the public perception of the sound that drones create during overflights or manoeuvres. When it comes to drones used for healthcare
purposes (as opposed to package delivery), this is the very first sound study globally. Drones have a more tonal noise signature, and are potentially more annoying, which is a concern for noise and health professionals and presents significant risks to the introduction and economic viability
of this technology. This paper describes a methodology developed to use online listening tests to capture people's responses to the sound of drones for the specific context of medical supply delivery.
Maximum Fast time-weighted levels - When can a transient be seen as a Dirac impulse?
Authors: Zeitler Berndt , Hoeller Christoph , Reinhold Steffi
Published: December 2023

It is common practice to use maximum FAST time-weighted sound pressure levels to assess transient impact noise, as these levels correlate well with human perception of impact noise. Maximum FAST time-weighted levels are known to be dependent on the reverberation time of the receiving
room. In previous studies, an analytical correction term was developed using a Dirac impulse. The correction term is used to calculate the maximum FAST time-weighted levels from peak sound pressure levels. Peak levels are independent of the reverberation time of the room. Applying the correction
term makes it possible to compare measurement results from different rooms. The correction term has been validated in several studies for the standard rubber impact ball. In this paper, the influence of the source signal (Dirac impulse) on the correction term is studied. Analytical and numerical
models are employed to investigate the consequences of stretching the impulse in time and of changing its shape. The results are compared with empirical solutions developed in other studies.
Development of acoustic material with inline cavity structure for design of operators' cabins in mineral processing plants
Authors: Sahu Nihar Ranjan , Mandal Bibhuti Bhusan
Published: December 2023

Operators of mineral processing plants are exposed to noise levels that may reach up to 100 dB(A). The aim of this study was to find appropriate acoustic materials for the construction of cabins that can protect the operators by reducing noise levels by at least 15 dB(A) in the specific
frequency range of 0.5-5 kHz, as the human ear is more sensitive to these frequencies. 3D printed material made from standard resin with an internal inline cavity structure was selected for the design. The position of the cavity in the structure and perforation ratio were varied to investigate
their acoustic properties. Acoustic properties such as the Sound Absorption Coefficient (SAC) and Sound Transmission Loss (STL) were measured using the Impedance Tube Apparatus. A maximum SAC of 99.6% was observed at 5.225 and 5.625 kHz among the test samples. The peak SAC shifted towards
lower frequencies when the cavity was away from the inlet port. By decreasing the perforation ratio from 13.25% to 1.28%, the STL increased up to 48 dB. We conclude that our designs have great potential for the construction of operator's cabins which provide attenuation of at least 20 dB in
the desired frequency range.
Development of Reference Energy Mean Emission Level Models for Traffic Noise from Cement Concrete Pavement in Mid-Sized Cities in India
Authors: Upadhyay Saurabh , Parida Manoranjan , Kumar Praveen , Kumar Brind
Published: December 2023

The purpose of this study is to establish the Reference Energy Mean Emission Level (REMEL) for different types of vehicles in the mixed traffic flow on cement concrete roads in the mid-sized city of Kanpur urban area. REMEL is a key factor in a traffic noise propagation model. In Kanpur,
data were collected at the location of Panki under free-flow traffic conditions on a good surface with a straight alignment. A total of 4,390 data sets for nine different vehicle categories (buses, trucks, tractor-trailers, light commercial vehicles, three-wheelers, cars, motorcycles, e-rickshaws,
and non-motorized vehicles) were collected as part of this study. The noise level (Leq) was measured using a Type-1 Sound Level Meter positioned at 7.5 metres from the centre of the nearest lane for each passing vehicle, while the vehicle's speed was also recorded simultaneously. The regression
analysis indicated a strong relationship between Leq and vehicular speed for all vehicle categories. This study provides valuable insights about the noise emission characteristics of different vehicles in mixed traffic conditions in India.