bluuebunny/crossref_metadata_2025 huggingface dataset:
Search for and Identification of Young Compact Galactic Supernova Remnants Using THOR
Authors: Ranasinghe Sujith , Leahy Denis , Stil Jeroen
Published: September 2021

Young Supernova remnants (SNRs) with smaller angular sizes are likely missing from existing radio SNR catalogues, caused by observational constraints and selection effects. In order to find new compact radio SNR candidates, we searched the high angular resolution (25″) THOR radio survey of the first quadrant of the galaxy. We selected sources with non-thermal radio spectra. HI absorption spectra and channel maps were used to identify which sources are galactic and to estimate their distances. Two new compact SNRs were found: G31.299-0.493 and G18.760-0.072, of which the latter was a previously suggested SNR candidate. The distances to these SNRs are 5.0±0.3 kpc and 4.7±0.2 kpc, respectively. Based on the SN rate in the galaxy or on the statistics of known SNRs, we estimate that there are 15–20 not-yet detected compact SNRs in the galaxy and that the THOR survey area should contain three or four. Our detection of two SNRs (half the expected number) is consistent with the THOR sensitivity limit compared with the distribution of integrated flux densities of SNRs.
A real-time music detection method based on convolutional neural network using Mel-spectrogram and spectral flux
Authors: Hao Yiya , Chen Yaobin , Zhang Weiwei , Chen Gong , Ruan Liang
Published: September 2021

Audio processing, including speech enhancement system, improves speech intelligibility and quality in real-time communication (RTC) such as online meetings and online education. However, such processing, primarily noise suppression and automatic gain control, is harmful to music quality
when the captured signal is music instead of speech. A music detector can solve the issue above by switching off the speech processing when the music is detected. In RTC scenarios, the music detector should be low-complexity and cover various situations, including different types of music,
background noises, and other acoustical environments. In this paper, a real-time music detection method with low-computation complexity is proposed, based on a convolutional neural network (CNN) using Mel-spectrogram and spectral flux as input features. The proposed method achieves overall
90.63% accuracy under different music types (classical music, instruments solos, singing-songs, etc.), speech languages (English and Mandarin), and noise types. The proposed method is constructed on a lightweight CNN model with a small feature size, which guarantees real-time processing.
Measurement and Analysis of Torque Ripple in Inverter Driven Electric Machines
Authors: Marks Mitchell
Published: September 2021

Torque ripple in electric machines can create both noise and vibration. While torque ripple is often well understood theoretically, it is much more difficult to accurately predict and measure. Often torque ripple is measured as a function of magnets and slot interaction at extremely
low speed, but this can only be extrapolated to understand its implications for noise and vibration and is not useful for understanding torque response during dynamic scenarios like a change in load. The slow speed method of measurement also neglects possible switching effects on the torque
profile. This paper will explore challenges in measuring the different sources of torque ripple and give an alternative method to measure torque ripple at higher speeds and also dynamically. This will include best practices and examples.
Community noise assessment of urban air mobility vehicle operations using the FAA Aviation Environmental Design Tool
Authors: Rizzi Stephen , Rafaelof Menachem
Published: September 2021

In contrast to most commercial air traffic today, vehicles serving the urban air mobility (UAM) market are anticipated to operate in communities close to the public at large. The approved model for assessing environmental impact of air traffic actions in the United States, the Federal
Aviation Administration's Aviation Environmental Design Tool (AEDT), does not support analysis of such operations due to a combined lack of a UAM aircraft performance model and aircraft noise data. This paper discusses the initial development of a method to assess the acoustic impact of UAM
fleet operations on the community using AEDT and demonstrates its use for representative UAM operations. In particular, methods were developed using fixed-point flight profiles and user-supplied noise data in a manner that avoids unwanted behavior in AEDT. A set of 32 routes in the Dallas-Ft.
Worth area were assessed for single and multiple (fleet) operations for two concept vehicles.
Deep Learning-based Health Indicator for Better Bearing RUL Prediction
Authors: Kim Taewan , Lee Seungchul
Published: September 2021

The prognostic performance of data-driven approaches closely depends on the features extracted from the measurement. For a high level of prognostic performance, features must be carefully designed to represent the machine's health state well and are generally obtained by signal processing
techniques. These features are themselves used as health indicators (HI) or used to construct HIs. However, many conventional HIs are heavily relying on the type of machine components and expert domain knowledge. To solve these drawbacks, we propose a fully data-driven method, that is, the
adversarial autoencoder-based health indicator (AAE-HI) for remaining useful life (RUL) prediction. Accelerated degradation tests of bearings collected from PRONOSTIA were used to validate the proposed AAE-HI method. It is shown that our proposed AAE-HI can autonomously find monotonicity and
trendability of features, which will capture the degradation progression from the measurement. Therefore, the performance of AAE-HI in RUL prediction is promising compared with other conventional HIs.
Validation setup for the investigation of aeroacoustic and vibroacoustic sound emission of confined turbulent flows
Authors: Maurerlehner Paul , Schoder Stefan , Floss Sebastian , Tieber Johannes , Steiner Helfried , Brenn Günter , Kaltenbacher Manfred
Published: September 2021

Confined flows induce sound at certain flow conditions, which can be annoying in electric vehicles due to the absence of combustion noise. Noise in internal flow may occur due to unfavorable flow-guiding geometries caused by the complex packaging required in engine compartments of modern
vehicles. The flow-induced sound is emitted at duct openings (e.g., ventilation inside the passenger cabin). It also originates from the vibroacoustic emissions of the flow-guiding structure excited by the flow. We propose a modular validation procedure for aeroacoustic simulations of confined
flows. The experimental setup includes the vibroacoustic emission of the involved flow-guiding structure. The test rig consists of a sensor system, a high-pressure blower, modular pipe sections, and absorbers, which decouple the system from blower noise and avoid acoustic reflections at the
pipe exit. A sufficiently long straight inlet section ensures fully developed flow conditions entering the investigated region. For capturing the vibroacoustic sound radiation of the flow-guiding structure, the measurement object and the surrounding microphones are encapsulated in a wooden
box, lined with micro-perforated plates. Measurement results of a straight pipe and a pipe with a half-moon-shaped orifice are presented. Additionally, the sound generation is reproduced by Lighthill's aeroacoustic analogy applying a hybrid approach.
Applicability of MEMS microphones for environmental sound level monitoring
Authors: Oatley James , Storey Craig
Published: September 2021

This paper explores the challenges associated with the integration of MEMS microphone technology into IEC 61672 classified or type-approved environmental sound level monitors. A comparison is drawn between MEMS microphones and electret condenser capsule microphones to highlight key
performance differences within the technologies, and a basic integration method for both technologies is suggested. A review of the IEC 61672 and type-approval standards is conducted against the suggested integration method for a MEMS microphone; key shortcomings are reported and objectively
reviewed. Development trends for MEMS microphones are explored, providing key insights into the progression of the technology against electret condenser capsule microphones. Furthermore, the evolution of environmental sound level monitoring systems is explored with a key focus on networked
and sound localisation technology. The importance of MEMS microphones within the evolution of environmental sound level monitoring systems is presented alongside key arguments for the practical suitability of MEMS technology over electret condenser capsule technology.
A conjugate gradient least square based method for sound field control
Authors: Libianchi Pierangelo , Agerkvist Finn T. , Shabalina Elena
Published: September 2021

In sound field control, a set of control sources is used to match the pressure field generated by noise sources but with opposite phase to reduce the total sound pressure level in a defined area commonly referred to as dark zone. This is usually an ill-posed problem. The approach presented
here employs a subspace iterative method where the number of iterations acts as the regularization parameter and controls unwanted side radiation, i.e. side lobes. More iterations lead to less regularization and more side lobes. The number of iterations is controlled by problem-specific stopping
criteria. Simulations show the increase of lobing with increased number of iterations. The solutions are analysed through projections on the basis provided by the source strength modes corresponding to the right singular vector of the transfer function matrix. These projections show how higher
order pressure modes (left singular vectors) become dominant with larger number of iterations. Furthermore, an active-set type method provides the constraints on the amplitude of the solution which is not possible with the conjugate gradient least square algorithm alone.
The Performance of a Low Berm in Reducing Traffic Noise
Authors: Donavan Paul , Janello Carrie
Published: September 2021

Traffic noise measurements were made behind a low, earth berm and in an adjacent open field to estimate insertion loss. The traffic was comprised of a mix of light vehicles, heavy trucks, and some medium trucks. The berm had a height of 1.65 meters above the roadway and began at the
outside shoulder of a four-lane highway along U.S. Highway 101 in Northern California. Two microphone positions were located on the far side of the berm at distances of 28 and 40 meters from the center of the near lane of vehicular traffic. Away from the berm, a microphone was placed in an
open field at 28 meters from the highway at a site upstream of the berm. The difference between the open location and those behind the berm were 11.6 and 9.9 dB for the 28- and 40-meter locations, respectively. The reductions obtained with the berm are compared to double edge diffraction theory
and acoustic scale model results from the literature. The results of this study are reviewed in this paper and a comparison to FHWA Traffic Noise Model results is presented.
Prediction of the variability of noise emissions from construction sites using Monte-Carlo simulation
Authors: Davis Dave
Published: September 2021

Noise emissions from construction sites are inherently unsteady. Noise emissions vary due to many causes, including the noise sources frequently changing in location, orientation, the types of activities they perform, and the acoustic shielding due to structures and/or terrain. The
noise that arrives at receivers from construction site equipment can fluctuate over all time scales, from seconds to hours, days, months or years. Prediction of noise levels typically assumes either a "worst-case" approach in which all noise sources are assumed to be operating simultaneously,
or by predicting an "energy-average" (Leq) level over a long time period. In the latter case, an energy-average (Leq) noise level is predicted at receivers, based on the anticipated percentage utilisation of the various noise sources on the construction site - that is, the fraction
of time that each item of equipment is operating or not during the averaging time period. This paper presents a method that may be used to estimate the variability of noise emissions from the site and the corresponding noise immissions at receivers using the Monte-Carlo simulation method.
Using this method, the expected minimum, maximum, percentiles and energy-average (Leq) noise immission levels at receivers can be predicted.
Noise codes and acoustical design criteria for distribution facilities
Authors: Conaway Michael , Mueller Benjamin , Keefe Joseph
Published: September 2021

Distribution and warehouse-type facilities are routinely constructed all over the country and the world. On-site noise sources for this type of facility include heavy trucks, delivery vehicles, and rooftop HVAC equipment. Stationary noise is often more clearly regulated than mobile
noise sources. To protect the public, appropriate criteria need to be established for all sources. Some jurisdictions have quantitative regulatory limits in place that may be used as design criteria while others may have less helpful qualitative code language or no noise code at all. A review
of common metrics found throughout the U.S. is presented to understand code language that appropriately protects the public for specific sources. In addition, it is useful to analyze and discuss common criteria applied in the absence of quantitative code limits.
NEMO project: developing a N-RSD (Noise Remote Sensing Device) to identify high noise emitters in the road traffic flow
Authors: Ertsey-Bayer Maximilian , Kirchhoff Nikolas , Alves Sonia , Peeters Bert , Henriksen Viggo , Berge Truls
Published: September 2021

NEMO (Noise and Emissions MOnitoring and Radical mitigation) is a research project aiming at developing an autonomous system to detect noise and air pollutant emissions from individual vehicles within the traffic flow. The objective is to identify high emitters within the normal traffic.
For noise, a high emitter is a vehicle that is either in a poor or modified condition (e.g., with an illegal or malfunctioning exhaust) or that is driven in a noisy way (fast acceleration, high engine speed in low gear, etc.). A vehicle that has been type approved, is well maintained, and
is driven under normal conditions is never a high-emitter vehicle, even if it is subjectively perceived as annoying. A Noise Remote Sensing Device (N-RSD) is being developed. This device will capture, for each individual vehicle, the driving conditions (vehicle speed, acceleration, engine
speed and load) and the single-event noise levels and spectral characteristics. The noise levels will be normalized to comparable driving conditions and fed into a classification model. The classification model will then be able to identify the high emitters vehicles. When finished, the NEMO
system will allow cities and road authorities to reduce annoyance and health impacts from noisy and polluting vehicles, for instance by raising awareness among drivers or by restricting access to low emission zones.
Investigating acoustics and wave behaviour in cross-laminated timber panels
Authors: Fenemore Chiaki , Yang Yi , Kingan Michael , Mace Brian
Published: September 2021

Cross-laminated timber (CLT) is a timber product that is becoming increasingly popular in construction in NZ because of the ability to prefabricate panels off-site, as well as being lightweight and sustainable compared to other building materials. There is currently a lack of information
on its acoustical properties, as the complex geometry through the thickness means it is difficult to model and predict sound transmission. The WFE (wave and finite element) method has been employed as it allows for a small segment of a material to be modelled using standard FE methods and
can incorporate several material layers. It then requires finding the mass and stiffness matrices of the segment and post-processing them to determine the wave behaviour of the structure as a whole. The WFE method was used to model the sound transmission of several different CLT panels and
these results were compared against measurements taken by the National Research Council Canada. In-house testing was also performed to obtain experimental wavenumbers, and these were also compared to wavenumbers produced by the WFE method.
Field Test Research on Environmental Noise Characteristics in the Throat Area of Metro Depot
Authors: He Lei , Song Ruixiang , Yang Jie , Wu Yubin , Wu Yanan
Published: September 2021

Environmental noise pollution is the primary environmental problem faced by the superstructure of metro depots. The throat area of depot is prone to high wheel-rail impact noise due to the use of seam lines, multiple joints, turnouts and small radius curves. The noise exerts through
fire and ventilation openings on the side walls, which may cause high annoyance to the residents in the superstructures both on the upper cover and surrounding areas. In this paper, a field test was condected on the environmental noise in the throat area of metro depot. The noise of the trackside
and adjacent open space were recorded, and the time-frequency domain characteristics and statistical characteristics and attenuation law of the noise generated by train operation in the throat area were analyzed. The research results have certain guiding significance for the prediction and
control of noise in the throat area of the depot.
Exploring the Audio-Visual Interaction in a Dental Clinic Through the Restorative Environment
Authors: Uğurlu Zeynep , Yılmazer Semiha
Published: September 2021

The aim of this study is to examine the effects of audio-visual interaction in an indoor acoustic environment. The research focused on the waiting area of a dental clinic. The dental clinic is visited, and binaural audio-video recording is made. After, a listening task is given to the
ten participants in three scenarios. Three experiment settings were designed for each scenario. The first experimental group was the control group who had the soundscape of the real environment; the second group, which is the audio group, only had the audial stimuli with the natural sound
which is added to the real environment; and the third group, which is the audio-visual group, had both visual stimuli with an image of nature and audial stimuli. A listening task questionnaire and Perceived Restorativeness Soundscape Scale (PRSS) interpretation questionnaire were given to
the participants. The results showed that the participants in the third group were found to perceive the indoor soundscape more positively than the other two groups.
Sell and Buy Quiet - the extended concept to reduce noise (at work and at home)
Authors: Heisterkamp Fabian , Bengtsson Ryberg Johanna , Jacques Jean , Verdaasdonk Alwin
Published: September 2021

Despite progress in legislation, e.g. laws requiring employers to assess and address the noise risk for their workers, and in the use of new technologies, e.g. battery powered tools or gardening equipment, noise-induced hearing loss remains a problem even today. The NOise MAchinery
Directive (NOMAD) Task Force of the European Member States cooperating in market surveillance has raised the awareness of many relevant stakeholders regarding the need for cooperation between manufacturers of products emitting noise and their users. A promising means to deal with the noise
problem is to make possible and effective a real competition towards quieter machines and equipment, so that market forces drive the technological development. To that end, we introduce the concept of Selling and Buying Quiet and address the issues hindering its application. These became evident
during NOMAD Phase 2, in particular at NOMAD Workshop 2 in 2019. The issues comprise general aspects, e.g. education on proper determination of noise emissions by manufacturers and use of noise information by machine users, as well as specific problems with existing EU legislation. Finally,
we provide ideas and set goals to improve the situation, so that Buying and Selling Quiet will become a reality.
Pitch strength and annoyance of acoustic analogs of flutter echo - a pilot study
Authors: Balant Anne , Lai Heather , Wilson Vayda M.
Published: September 2021

The impetus for this pilot study was the observation of flutter echoes on the aisle of a church with a barrel-vaulted ceiling. When source and receiver height were comparable, the flutter echoes consisted of a 39-msec repeating pattern of three short pulses that persisted for reverberation
times of up to 5 sec. The disruptive quality of these echoes perceptually was striking. It was hypothesized that the perception of a sequence of rapidly alternating periodicity pitches might be the source of this disruptive quality. A pilot study was conducted to assess the perceived pitch,
pitch strength, and annoyance of isochronous and anisochronous synthetic pulse trains involving up to three different inter-pulse intervals per pattern. Intervals of the anisochronous pulse trains were controlled to create harmonic and inharmonic relationships among the intervals, which ranged
from 5-20 msec. Twelve adult college students participated in the study remotely via videoconferencing due to social distancing requirements. A modified category scaling method was used. Participants positioned a slider on a graphical user interface to reflect their ratings of pitch strength
and annoyance and used a slider to adjust the frequency of a reference tone for pitch matching. Results and implications for further research will be presented.
A design framework for absorption and diffusion panels with sustainable materials
Authors: Dessi-Olive Jonathan , Hsu Timothy
Published: September 2021

Architectural acoustics has not traditionally had unified design methods that specify acoustical performance, visual appearance, and sustainable material selection, leading to underperforming products that contribute to a waste stream of petro-chemical foam and fiberglass materials.
The evolution of design, materials, and manufacturing techniques in recent years has created new opportunities to reimagine acoustic diffusers and absorbers. Previous work by the authors have demonstrated a unifying framework for design and collaboration in architectural acoustics. The framework
uses visually-driven computational design method inspired by shape grammars that generate a wide range of acoustic phase grating diffuser arrays that display unique visual and performative qualities. Simulation and evaluation metrics to assess the complexity of each design are rated in terms
of their diffusion and absorption coefficients and a visual aesthetic coefficient. This paper extends the framework to include digital fabrication protocols and sustainable material specifications - including the use of fungi-based materials. Built prototypes demonstrate an expanded acoustic
design space that gives acousticians the potential to create custom diffuser shapes with precise acoustical response. The innovative combination of computational design methods and sustainable fabrication protocols will be discussed, and the acoustic properties of arrays will be evaluated
and compared to simulations of corresponding designs.
Robust prediction metrics for structure-borne noise in timber buildings
Authors: Flodén Ola , Persson Peter
Published: September 2021

This paper presents an investigation of prediction metrics for structure-borne noise in timber buildings, based on the vibration response of the structure. The purpose of the study is to derive a robust measure for predicting structure-borne noise in timber buildings based solely on
the vibration response; a measure with a known correlation to the actual acoustic response. Such a measure is useful for establishing simplified numerical prediction models, and for making robust assessments of different design alternatives. The procedure has previously been applied to automotive
applications with a valuable outcome for the industry. The vibration and sound pressure responses in a room of a multi-storey building are calculated using the finite element method. As excitation, a harmonic unit point load (20-300 Hz) located at another storey of the building is used. Based
on the structural and acoustic response fields, scalar values are calculated by performing spatial and frequency domain averaging and summations. Various methods for calculating scalar values from the vibration response are investigated. The correlation between the vibration scalar values
and the acoustic scalar values are presented.
The challenges and successes of passive acoustic treatments on the International Space Station
Authors: Smith-Dalenberg Holly , Allen Christopher S. , Limardo-Rodriguez Jose G.
Published: September 2021

Habitable space environments pose unique challenges to the selection of passive acoustic treatments used to mitigate noise. On the International Space Station, strict regulations regarding flammability, particulate release, and off-gassing must be considered during material selection,
resulting in the exclusion of many common acoustic treatments used in ground-based applications. The Johnson Space Center Acoustics Office has identified a small subset of acoustic absorption and barrier materials that meet these stringent requirements, and has developed numerous treatments
for noise mitigation, including duct-wrapping and liners, acoustic absorption and barrier blankets, and mufflers. The Acoustics Office utilizes impedance and transmission loss tubes to optimize the layering of acoustic materials for these treatments while observing restrictive volume and mass
limits. Future acoustic mitigation development will focus on moisture and microbial-resistant materials and treatments that can be utilized in enclosed spaces that require higher scrutiny in regards to cleanliness, such as waste management bays and surfaces surrounding exercise equipment or
galleys.
Field measurement of reverberation time and average absorption of one high-rise building room by road traffic noise penetrating facade
Authors: Zhang Jiping , Wang Zheming , Ma Heng , Wang Weike
Published: September 2021

The facade insulation (FI) is one choice for Road traffic noise (RTN) at a high-rise accommodation building nearby a motor road. The weakness of FI is from window, so the window insulation (WI) is also a prioritized descriptor. ISO16283-3 states a field method to measure FI using RTN.
However, in room acoustics, besides FI, reverberation time (RBT) or indoor average sound absorption (IASB) are another two un-ignorable descriptors. When the value of IASB is small, the indoor noise is not only contributed from penetrating façade RTN, but also supplemented by the residual
sound from high reverberation field, weakening FI. As a parallel to ISO16283-3, this paper suggests an engineering method to measure RBT and IASB of one high-rise building room close to a motor road by penetrating façade RTN. It can supply a convenient tool for the field measurement
of RBT and IASB with RTN. At the end, we made a field measurement of RBT, IASB, and WI at a hotel room nearby a viaduct in Hangzhou of China, assistant to adjust RBT or IASB and WI so as to improve the sound quality of the hotel. Further, the method can extend to the lines of rail, aviation,
and shipping.
MEMS microphone intensity array for cabin noise measurements
Authors: Spehr Carsten , Ernst Daniel , Raumer Hans-Georg
Published: September 2021

Aircraft cabin noise measurements in flight are used toto quantify the noise level, and to identify the entry point of acoustic energy into the cabin. Sound intensity probes are the state-of-the-art measurement technique for this task. During measurements, additional sound absorbing
material is used to ease the rather harsh acoustic measurement environment inside the cabin. In order to decrease the expensive in-flight measurement time, an intensity array approach was chosen. This intensity probe consists of 512 MEMS-Microphones. Depending on the frequency, these microphones
can be combined as an array of hundreds of 3D- intensity probes. The acoustic velocity is estimated using a high order 3D finite difference stencil. At low frequencies, a larger spacing is used to reduce the requirement of accurate phase match of the microphone sensors. Measurements were conducted
in the ground-based Dornier 728 cabin noise simulation as well as in-flight.
Influence of mobility completeness and source behavior on the robust-ness of Transfer Path Analysis and Source Characterization methods: A numerical study.
Authors: Prenant Simon , Padois Thomas , Dupont Thomas , Doutres Olivier
Published: September 2021

Structure borne noise is considered a major contribution to the noise generated inside aircrafts. In order to analyze it, engineering methods have been developed such as Transfer Path Analysis (TPA) and Source Characterisation (SC). These methods are based on active and passive properties
of the source and the receiving structure being coupled or decoupled. The theoretical formulation requires mobility according to all Degrees Of Freedom (DOFs) and rotational DOFs represent a challenge for experimental application. To fulfill the mobility matrix, indirect method have been developed
and specific sensors have been proposed, resulting in a more complex experimental set-up and an increase in measurement uncertainties. The necessity of assessing the full matrix completeness is thus still questionable. The robustness of these methods with respect to the matrix completeness
and the source behavior is investigated numerically in this work. A numerical model has been developed to simulate vibrating sources with simple or complex vibratory behavior and to assess the mobility matrices for any completenesses. Velocity on the receiving structure is used as a target
indicator. The influence of source behavior and completeness are discussed and the results show that the required mobility completeness depends on the source behavior.
Influence of the plate thickness and material properties on the violin top plate modes
Authors: Kaselouris Evaggelos , Orphanos Yannis , Bakarezos Makis , Tatarakis Michael , Papadogiannis Nektarios A. , Dimitriou Vasilis
Published: September 2021

In this paper we analyze the vibrational behavior of the violin top plate, for varying plate thickness and material properties via finite element method (FEM) numerical simulations. It is well known that the vibrational properties of the top plates of string instruments influence their
sound emission characteristics. Due to the impact of global warming on wood formation and due to their configurability, many manufacturers investigate the use of composite materials to produce musical instruments. Therefore, composite, carbon fiber reinforced epoxy (CFRE) prepreg along with
traditional wooden material, such as spruce, are adopted in this study. FEM modal analysis along with a frequency response function (FRF) FEM analysis are performed. The vibrational variations of the plate's response are computed under free conditions. The main vibrational modes and the natural
frequencies obtained by the simulations show the influence of the different mechanical and geometric properties on the top plate's vibrational response. The resulting eigenmode frequencies and shapes of the plate in relation to the varying thickness and the material properties used, are discussed.
The results of this study offer valuable information on the evaluation of the acoustical characteristics of violins and may be further used on their vibrational behavior optimization and control.
Experimental force reconstruction on plates of arbitrary shape using neural networks
Authors: Dare Tyler
Published: September 2021

Measuring the forces that excite a structure into vibration is an important tool in modeling the system and investigating ways to reduce the vibration. However, determining the forces that have been applied to a vibrating structure can be a challenging inverse problem, even when the
structure is instrumented with a large number of sensors. Previously, an artificial neural network was developed to identify the location of an impulsive force on a rectangular plate. In this research, the techniques were extended to plates of arbitrary shape. The principal challenge of arbitrary
shapes is that some combinations of network outputs (x- and y-coordinates) are invalid. For example, for a plate with a hole in the middle, the network should not output that the force was applied in the center of the hole. Different methods of accommodating arbitrary shapes were investigated,
including output space quantization and selecting the closest valid region.
Predicting acoustic performance of high surface area particle stacks with a poro-elastic model
Authors: Mo Zhuang , Song Guochenhao , Bolton J. Stuart , Lee Seungkyu , Seo Yongbeom
Published: September 2021

Because of the high sound absorption they offer at low frequencies, there is a growing interest in high surface area particles and how they might be applied in noise control. Therefore, a model that can accurately predict the acoustic behavior of this type of materials will be useful
in relevant applications. A poro-elastic model based on a combination of Biot theory and an existing rigid model of granular activated carbon (GAC) is introduced in the current work. The input parameters for this model consist of a certain number of properties that are known by measurement,
and a set of values obtained by matching the model prediction with acoustic measurements. Measured absorption coefficients and surface impedance of stacks of several types of different activated carbon particles are shown in this paper. A fitting procedure that determines the unknown parameters
is also described. It is shown that the model is able to predict the acoustic behavior of the particle stacks, and especially to capture the frame resonances at low frequencies, thus, validating the proposed model. Beyond the activated carbon used in the present tests, it is reasonable to
generalize this model to stacks of other high surface area particles.
Concert hall: acoustic design comparing analytical results and ray tracing
Authors: Sá Karina , Rocha Raquel Rossatto , Fengler Bárbara
Published: September 2021

With the intention of designing architecture for music and inspired by music, the J.C. Martins Concert Hall was created with 1008 seats and an approximate volume of 49400 ft³. Among all the architectural aspects considered, such as strategic location analyzed from the mass plan,
study of volumetries, acoustics is the highlight due to its importance and complexity of the project. The Concert Hall is the object of the present study, the purpose of the article is to compare the simulated results in the EASE software with the analytical results of the reverberation time
calculated by the Sabine and Eyering equations for the Concert Hall. Acoustic parameters such as reverberation time, clarity, among others, were simulated to verify the acoustic quality of the room in question. With that, it was possible to analyze and discuss the limitations of the analytical
method and the simulations. Even so, the results were satisfactory to reach the adequated indexes of the acoustic parameters.
Indirect determination of airflow resistance of textiles with reference samples
Authors: Rodríguez Vercher Juan Carlos , del Rey Romina , Alba Jesús
Published: September 2021

Airflow resistance is a non-acoustic parameter of great relevance in the acoustic characterization of porous materials. It is used in several sound absorbing material prediction models and it is also a control parameter for acoustic conditioning and insulation in different building
solutions. The ISO 9053 standard defines several methods to obtain it, using both direct measurements and indirect techniques. However, both procedures may involve problems related to the placement of the textile samples in the tube or to the stability of the samples during testing. In this
work, the use of reference materials to stabilize the measurement of thin materials is proposed. Airflow resistance results obtained for different materials in an impedance tube are presented. The tests have been carried out by following the Ingard & Dear method, as an indirect technique
accepted by the standard. Several material compositions with a wide range of airflow resistance values have been analyzed with different reference materials.
Noisy Motorcycles and Barriers and Quieter Pavements for Traffic Noise Abatement: Summaries of Two TQA Workshops
Authors: Donavan Paul
Published: September 2021

In the Technology for a Quieter America report, motorcycles were mentioned three times, once in terms of standard test methods and twice in relation to community noise. In New York City, motorcycles placed in the top 10 bothersome noise sources identified by residents. Although there
are regulated levels that manufacturers must meet, complaints about in-service motorcycle noise persist. To address this issue, a round table meeting was held in August 2012 with a broad spectrum of participants representing manufacturers, regulators, and other interested, knowledgeable engineers.
In preparation of the TQA report, a workshop entitled Cost-Benefit Analysis (CBA) for Noise Control found that CBA was being applied in the area of traffic noise mitigation in regard to the use of barriers and/or quieter pavement. To address the particular CBA issues for this topic, a workshop
was held in January 2014 with state and federal transportation officials and the research team responsible for the National Cooperative Highway Research Program NCHRP Report 738, Evaluating Pavement Strategies and Barriers for Noise Mitigation. The findings of these two meetings are summarized
in this paper.
A study on variations in excess attenuation due to ground surface and meteorological conditions based on a long-term outdoor sound propagation experiment
Authors: Yokota Takatoshi , Makino Koichi , Iizumi Genki , Tsutsumi Takuya
Published: September 2021

From the winter of 2018, outdoor sound propagation experiments (maximum horizontal range: 300 m) have been repeatedly conducted three times a day on weekdays at a glider airfield in Hokkaido, Japan. The ground condition of the experimental field is grass-covered in summer and snow-covered
in winter. In each experiment, impulse responses have been measured by time-stretched pulse method and excess attenuation has been obtained at receiving points. Meteorological data at the field has been also measured. Based on the data of excess attenuation collected under various meteorological
conditions over a long period, variation in sound propagation characteristics due to the differences in ground surface condition and meteorological condition has been investigated. The numerical analysis based on the GFPE method has been also carried out with changing the parameter of meteorological
condition and ground surface condition. By comparing the results with the experimental data, the prediction method of the variations in excess attenuation has been also investigated.
A research on assessment of soundscape in urban area by means of Caption Evaluation Method: effects of context on evaluation of soundscape
Authors: Akita Takeshi , Tomioka Masahiro , Yu Hanui , Sano Naoko , Matsuo Ayako
Published: September 2021

Caption Evaluation Method is a technique that was developed in Japan to learn about the reason of evaluation of landscape. The investigative method is a formalized one and can show the element of landscape that a person focused on when he made an evaluation of the landscape, and the
reason why he made a good or bad evaluation on it. In the present research, Caption Evaluation Method is applied to the survey of soundscape in urban area. Twenty-one subjects were instructed to walk along the predetermined route, and to take a picture and make evaluation of soundscape when
they found out sound that attracted their attention. They rated the sound as good, bad or normal, and they reported the character and impression of it by formalized questionnaire. As a result, one hundred fifty-seven sound elements were obtained. They were classified under the proposed way
in the previous research. Results show that traffic noise is assessed bad by almost all the people because of its noisy character, but sound from information display system receives different assessment among people. It is supposed that evaluation of not so noisy sound can be easily affected
by the context in a person's mind.
Comparison of Estimation Methods of Room Impulse Responses in Local Region Using Small Number of Microphones
Authors: Matsuhashi Haruka , Tsunokuni Izumi , Ikeda Yusuke
Published: September 2021

Measurements of Room Impulse Responses (RIRs) at multiple points have been used in various acoustic techniques using the room acoustic characteristics. To obtain multi-point RIRs more efficiently, spatial interpolation of RIRs using plane wave decomposition method (PWDM) and equivalent
source method (ESM) has been proposed. Recently, the estimation of RIRs from a small number of microphones using spatial and temporal sparsity has been studied. In this study, by using the measured RIRs, we compare the estimation accuracies of RIRs interpolation methods with a small number
of fixed microphones. In particular, we consider the early and late reflections separately. The direct sound and early reflection components are represented using sparse ESM, and the late reflection component is represented using ESM or PWDM. And then, we solve the two types of optimization
problems: individual optimization problems for early and late reflections decomposed by the arrival time and a single optimization problem for direct sound and all reflections. In the evaluation experiment, we measured the multiple RIRs by moving the linear microphone array and compare the
measured and estimated RIRs.
Parametric optimization of aircraft arrival trajectories for aviation noise mitigation using BADA4 performance model
Authors: Behere Ameya , Puranik Tejas , Kirby Michelle , Mavris Dimitri
Published: September 2021

Successful mitigation of aviation noise is a key enabler for sustainable aviation growth. A key focus of this effort is the noise arising from aircraft arrival operations. Arrival operations are characterized by the use of high-lift devices, deployment of landing gear, and low thrust
levels, which results in the airframe being the major component of noise. In order to optimize for arrival noise, management of the flap schedule and gear deployment is crucial. This research aims to create an optimization framework for evaluating various aircraft trajectories in terms of
their noise impact. A parametric representation of the aircraft arrival trajectory will be created to allow for the variation of aircraft's flap schedule. The Federal Aviation Administration's Aviation Environmental Design Tool will be used to simulate the aircraft trajectory and performance,
and to compute the noise metrics. Specifically, the latest performance model from EUROCONTROL called "Base of Aircraft Data - Family 4" will be used. This performance model contains higher fidelity modeling of aircraft aerodynamics and other characteristics which allows for better
parametric variation.
Temporal integration of partial loudness of helicopter-like sounds
Authors: Schlittenlacher Josef , Moore Brian C. J.
Published: September 2021

When developing new vehicles that are to be operated in existing background noise, such as electric vertical take-off and landing aircraft (eVTOLs) in cities, a sound design goal should be to minimize the loudness in the given background noise. Rotorcraft sounds are characterised by their pulses, and the choice of rotor size and number allows to vary the temporal characteristics. We asked participants to compare the loudness of pulse trains with pulse durations of 1, 2, 5, 10 and 20 ms and a pulse rate of 20 Hz in a two-interval, two-alternatives forced choice task and a 1-up/1-down procedure. Street noise was presented simultaneously with the pulse trains, and had the same root-mean-square (RMS) level as the fixed reference pulse train of about 65 dB SPL. First results indicate that the sounds with a short pulse duration need considerably less RMS level to result in the same loudness as a long pulse duration, i.e. the partial loudness of shorter pulses is higher at the same equivalent sound pressure level.
The effects of aural and visual factors on appropriateness ratings of residential spaces in an urban city.
Authors: Tan Johann Kay Ann , Lau Siu-Kit , Hasegawa Yoshimi
Published: September 2021

This study investigates the aural and visual factors that influence appropriateness perception in soundscape evaluations in residential spaces, where people may spend most of their time in. Appropriateness in soundscape is derived from the expectation of sound sources in a specific
environment, place or function heard by a listener. Appropriateness of soundscapes in 30 locations in an urban residential environment is investigated with varying landscape, visual and aural elements through a questionnaire. Participants experienced the soundscape in-situ and were asked to
evaluate the appropriateness of soundscape as well as the dominance of specific sound sources such as traffic, human activities and birdsongs in the residential space. The effect of type of traffic on appropriateness is also investigated. A strong relationship is found between appropriateness
and affective soundscape qualities such as pleasantness, highlighting the importance of considering appropriateness in soundscape research. In audio-visual combination of specific elements and the partial correlation with appropriateness, specific aural sound sources are found to correlate
uniquely to appropriateness while controlling for relevant visual elements, whereas visual elements became redundant in its partial correlation to appropriateness. Residents' perception of appropriateness is found to likely be more dependent on the individual visual elements rather than the
overall landscape. This study investigates the factors that influences appropriateness perceptual in soundscape evaluations in residential spaces, where people may spend most of their time in. Appropriateness in soundscape is derived from the expectation of sound sources in a specific environment,
place or function and heard by a listener. The appropriateness of soundscapes of 30 locations in an urban residential environment is investigated with varying visual (greenery, building, waterbody) and aural elements through a questionnaire approach. Participants experienced the soundscape
in-situ and were asked to evaluate the appropriateness of soundscape as well as the dominance of specific sound sources such as traffic, human activities and birdsongs in a residential space. The type of traffic is also investigated to explore the effect of traffic load on appropriateness.