bluuebunny/crossref_metadata_2025 huggingface dataset:
Fundamental noise characterization of a ducted propeller in hover
Authors: Simon Frank , Schiller Noah H. , Zawodny Nikolas S. , Pettingill Nicole A. , Galles Matthew B.
Published: February 2023

Unmanned aerial vehicles (UAVs) are currently being used for reconnaissance missions, tactical surveillance, and infrastructure inspection. When legislation allows it, these devices will provide additional services close to inhabited areas, which could lead to noise complaints. On most
UAVs, the propellers are the dominant source of noise. As a result, researchers have studied the impact of propeller shape and blade count on noise. Much of this work, however, has focused on isolated propellers. While different UAV concepts are equipped with ducts for aerodynamic and protection
reasons, few studies focus on the acoustic benefit of ducts, as is achieved, for example, on turbofan aircraft. The objectives of this paper are: first, to simulate the noise radiation of a UAV propeller in static conditions based on its location in a hard wall duct; second, to analyze the
contribution of the different acoustic source components (i.e., thrust, torque, and thickness); and third, to validate the approach with experiments conducted in the NASA Small Hover Anechoic Chamber over a range of propeller rotation rates. In this experiment, it is shown that the best attenuation
is achieved when the propeller is centered, axially, in the duct because of interference between upstream and downstream radiated waves.
Modified Acoustic Black Hole Profile for Improved Fatigue Performance
Authors: Keys Archie , Cheer Jordan
Published: February 2023

Acoustic black holes (ABHs) are realised via modifications to a structure that effectively reduce the structural wave speed, which increases the effect of damping treatments and thus enhances the achievable vibration attenuation. ABHs are commonly designed using a tapering thickness
profile and this leads to part of the ABH being very thin. Due to the focusing effect of the ABH, the thin section of the taper is also exposed to high amplitude vibrations and this raises concerns relating the vibration fatigue of the structure. This paper investigates the fatigue life of
an ABH taper used to terminate a beam using a numerical model, before a modified taper profile is proposed that aims to reduce the fatigue, while maintaining ABH performance. The effect of the power law used in the taper profile on the fatigue life is investigated and the potential trade-off
between performance and fatigue life is explored for both the unmodified and modified profiles.
Road traffic noise in European cities: Learnings from a European-wide study on the health impacts of road traffic noise.
Authors: Khomenko Sasha , Cirach Marta , Barrera-Gómez Jose , Pereira-Barboza Evelise , Iungman Tamara , Mueller Natalie , Foraster Maria , Tonne Cathryn , Thondoo Meelan , Jephcote Calvin , Gulliver John , Woodcock James , Nieuwenhuijsen Mark
Published: February 2023

Road traffic noise is one of the main environmental risks to health and wellbeing. We aimed to provide an in-depth assessment of available road traffic noise data and to estimate population exposure and health impacts for cities in Europe. We analyzed 724 cities and 25 greater cities
in 25 European countries. We retrieved road traffic strategic noise maps delivered under the Environmental Noise Directive (END) or available from local sources. We assessed noise exposure using the 24h day-evening-night noise level indicator (Lden) starting at exposure levels of 55 dB Lden
for the adult population aged 20 and over and estimated the health impacts of compliance with the World Health Organization (WHO) recommendation of 53 dB Lden. Two primary health outcomes were assessed: high noise annoyance and Ischemic Heart Disease (IHD), using mortality from IHD causes
as indicator. Almost 60 million adults were exposed to road traffic noise levels above 55 dB Lden, 11 million adults were highly annoyed and more than 3600 deaths from IHD could be prevented annually. A considerable number of adults are exposed to road traffic noise levels harmful for health.
Efforts to standardize the strategic noise maps and to increase data availability at the city level are needed to provide a more accurate and comprehensive assessment of the health impacts of road traffic noise.
Noise and soundscape in Welsh planning policy
Authors: McVay Martin
Published: February 2023

In Wales, noise policy now sits within the sustainable development framework of our Well-being of Future Generations Act. Under this Act, public bodies must look to the long term; take an integrated approach; involve a diversity of the population in decisions affecting them; work with
others in a collaborative way to find shared sustainable solutions; and act to prevent problems from occurring or getting worse. The Welsh Government has adopted a Noise and Soundscape Action Plan calling for the creation of appropriate soundscapes, meaning "the right acoustic environment
in the right time and place". We have rewritten Planning Policy Wales and included appropriate soundscapes amongst our National Sustainable Placemaking Outcomes. We committed to providing further guidance to support planning policy on air quality, noise and soundscape, and drafted a new
Technical Advice Note, with a supporting document on soundscape design. Soundscape design in Wales means more than just design of the sound environment. It is a process giving as much weight to people and context as to the sounds themselves, from the outset. This approach is expected to be
followed, referring to soundscape standards where appropriate, when and to the extent it may be expected to result in better placemaking.
Laboratory measurements on replaceable jack-up systems
Authors: Rodrigues Marina
Published: February 2023

Floating floor systems are part of state-of-the-art modern building technology. They are an efficient option to improve the acoustical performance of buildings and can be part of box-in-box systems installed in high-performance spaces. There are many types of high-performance floating
floor types, one of which is a jack-up system that guarantees that the floor is decoupled from the structural floor. With these systems, once the concrete has cured, the isolated slab is raised off the structure to the required void depth using pre-cast boxes. These boxes allow for easy adjustment
of the final floor height and, if the use of the room or load conditions change in the future, can also allow the replacement of the isolators inside them. Replaceable and inspectable acoustical floor systems are perceived as systems with lower sound insulation (airborne noise) than traditional
floating floor or non-replaceable jack-up systems. To measure airborne sound reduction and impact noise isolation of replaceable jack-up systems and confirm factors that can influence its performance, CDM Stravitec invested in a testing campaign where measurements were made considering many
variables, such as: concrete floating slab thickness; bearings type, air void depth, steel lid installed on top of each box and insulation material installed in the air void. This paper will present the findings of our testing campaign.
Reproduction of acoustic evanescent waves using wave field synthesis by controlling phase differences between monopole secondary sources
Authors: Kumar Akash , Puri Amrita
Published: February 2023

This paper is about the reproduction of acoustic evanescent waves using the linear distribution of discrete monopole secondary sources. The driving function for the actuation of a secondary source is derived using the theory of wave field synthesis. The analysis of the synthesized wave
field is done for different source excitation frequencies. A new method of creating more precise evanescent waves based on the phase difference between the sources is also presented. The simulation result shows that the driving function obtained using the WFS method results in the correct
synthesis of evanescent wave below aliasing frequency. Above the aliasing frequency, when the consecutive secondary sources are in antiphase, it will produce evanescent waves. Otherwise, propagating plane waves get produced. Different errors in the reproduced wave field which comes due to
the use of discrete and fixed array length are also investigated, and some solutions to mitigate those errors are presented.
A new sustainable material for in-situ absorption in noise barrier walls
Authors: Cowsill Andrew
Published: February 2023

Perforated macrocellular foams produced using recyclable polyolefin resins have existed as acoustic absorption panels for almost 20 years. They have broad acoustic absorption with good resistance to moisture, salt and UV exposure. Adoption of In-Situ sound reflection standards, in the
Rail and Road noise barrier industry; along with renewed focus on sustainable design has led to renewed interest in this technology. Traditional foam panel formats did not attain acceptable in-situ sound reflection performance. The purpose of this study was to evaluate an improved structure
of foam to the industry norms required of absorptive components of the noise barrier wall; and then subject this to a lifecycle analysis. A new structure showed good reflection results in-situ, using a reduced mass of raw material. The novel panel was evaluated to a range of acoustic and mechanical
testing standards to assess suitability for adoption in Noise Barrier Wall applications. The material was subsequently subjected to lifecycle analysis and the resulting product issued with an environmental product declaration. This paper concludes that the new material is well suited to widespread
use in in-situ category A3 noise barrier walls.
A virtual reality tool to aid in soundscapes in the built environment (SiBE) through machine learning
Authors: Yilmazer Semiha , Davies Patricia , Yilmazer Cengiz
Published: February 2023

Regarding the function and context of the space, virtual reality (VR) can be used for soundscapes design if the user behavior is predictable. This study enables the acoustic characterization of VR development tools to measure auditory perception based on user behavior. The research
question is whether soundscapes can be modeled according to the variable acoustic environments defined by the existing architectural features (e.g., prismatic, courtyard, vault, arched, mezzanine). A sound simulation algorithm in MATLAB was developed to extract room impulse response (RIR)
of the test environment in a virtual environment and to compare it with the real environment (RE). In the developed program, image source model (ISM) and ray trace were used to be performed the real-time acoustic source generation and real-time signal recording, image functions, data processing,
metric calculation operations (e.g., tonality and spectrogram). B&K 4292 omni-power loudspeaker, B&K 2716 power amplifier, and B&K 2250 hand-held analyzer were used to measure RIR in the RE. In addition to RIR and RT30, psychoacoustic metrics (e.g., loudness, sharpness, roughness,
and fluctuation strength) were measured in both environments. The results showed that sound simulation, based on ISM, demonstrates the validity and can be used for the acoustic characterization of VR development environments.
The Attenuation and Speech Intelligibility of the Gecko Helmet Used by the Royal National Lifeboat Institution
Authors: Jay Stephen
Published: February 2023

The RNLI operates a fleet of B Class Inshore Lifeboats around the UK and Ireland. To help keep their volunteers safe, crew members wear the Gecko helmet as part of their issued personal protective equipment. Anecdotal evidence from lifeboat crew has shown that wearing the helmet interfered
with the ability of volunteers to follow normal conversations and commands given under non-amplified situations. Objective measurements were undertaken at varying angles of incidence to quantify the attenuation of sound provided by the helmet at the location of the human ear along with objective
and subjective measurements of the intelligibility of speech while wearing the Gecko helmet. Analysis of data showed that the Gecko helmet provides limited noise attenuation at frequencies above 1kHz. Results of objective and subjective speech intelligibility tests show a reduction in the
speech transmission index score when the helmet was introduced into the experiment.
Design and validation of microperforated panel absorbers using Occam's razor and causal inference
Authors: Xiang Ning , Fackler Cameron, J. , Hoeft Michael
Published: February 2023

Microperforated panel absorbers in forms of micro-poles /-slits (MPP/MSP) can achieve high absorption. However, noise control practice usually requires broadband high absorption. Single- or double-layer MSP/MPP absorbers often cannot meet practical requirements. Multilayers become a
natural option. Multiple layers of MSP/MPP absorbers inherently complicates the design process upon a given design scheme. This work applies a Bayesian framework using a potentially multilayered prediction model. The Bayesian design involves two-levels of probabilistic inference to design
a parsimonious number of layers using the model-selection solution, a quantitative implementation of Occam's razor, while the parameter estimation is used to estimate MPP/MSP parameters given the selected number of multilayers. This probabilistic design process rapidly hones in on the MPP/MSP
parameters of each individual layer so that the overall composite meets the design goal. When experimentally validating the designed prediction upon the design scheme, manufacture inaccuracies may lead to deviations. In analyzing reasons of the deviations, this work further applies causal
inference to analyze the cause-effect relationship. To this end a causal model has also been established. Using both parametric prediction model for the absorption performance and the causal model for causal inference of the deviation causes, the Bayesian multilayer design can be satisfactorily
validated.
Spanwise Coherence Measurements of Porous Coated Cylinders in Uniform Flow
Authors: Xiang Zilun , Arcondoulis Elias , Maryami Reza , Liu Yu
Published: February 2023

A porous coated cylinder (PCC) generates weaker vortex shedding noise than a smooth cylinder placed in uniform flow. A key understanding of how the porous media relates to vortex shedding reduction is linked to the spanwise coherence length of the PCC at the near-wall region. To date,
few studies estimate the PCC spanwise coherence to be five-to-six outer diameters in length, yet a more comprehensive study is needed. This paper presents an experimental investigation conducted in an anechoic wind tunnel using a set of polyurethane PCCs tested with varying porosity, thickness
and at several Reynolds numbers. Spanwise coherence is estimated at various circumferential angles using (1) flush-mounted microphones distributed along the bare cylinder span, beneath the porous layer, to record surface pressure fluctuations, and (2) two hot-wire anemometry probes in the
near-wall flow field, where one probe remains in place and the other is shifted along the span. A transfer function of the porous layer is estimated based on the surface pressure and velocity fluctuations. The results presented here give some new visions of the spatial structure of vortex
shedding caused by porous materials, noise generating mechanisms and a fitting formula of spanwise coherence length of PCCs.
A traffic big data analysis on relationships between urban planning and traffic noise level--taking Dongguan Demonstration Area, China as an example
Authors: Song Jiaxun , Meng Qi , Kang Jian
Published: February 2023

With the promotion of smart city research, traffic big data has become a new way to study urban traffic noise. Taking Dongguan Demonstration Area, China as an example, this research discussed the relationships between traffic noise levels and urban plannings using geographic information
scienceGIS, global positioning system (GPS) techniques and OpenITS Organization OpenData. The results showed that, for the whole area, some planning factors, say global integration, local integration (R=500m), global betweenness, local betweenness (R=500m) and number of points of interest
(POIs) had significant positive correlations with the daytime traffic noise levels. Among them, the number of POIs had the strongest correlation with the traffic noise levels (r=0.560 p<0.01). However, the degree of influence of each variable on traffic noise levels can be changed with
geographical locations. This research also identified specific areas where traffic noise levels were negatively correlated with local integration and local betweenness, which had great potential to provide a recreational and peaceful place for people to walk. Therefore, the urban areas' centers
and fringes can be studied separately to effectively control traffic noise by changing the urban plannings.
Research on Sound Power Levels of Structure-Borne Noise of Viaducts Roads
Authors: Ikeya Kimikazu , Mori Tatsuaki , Itiki Tomoyuki , Fukushima Akinori
Published: February 2023

The authors studied the power levels of structure-borne noise of viaducts generated when tyres of running vehicles excite the road surface. The Acoustical Society of Japan's Research Committee on Road Traffic Noise describes the power levels of structure-borne noise are influenced by
viaduct type, running speed, and vehicle weight. This paper reports on the results of organizing the power levels per running speed and number of axles, measured by grouping large vehicles by their number of axles. The study confirmed that power levels tend to larger as the speed and number
of axles increase. Based on this result, the power-level setting equation applied in the prediction method of road traffic noise was revised.
Development of experimental Vibro-acoustic transfer function for a system with impact
Authors: Shripad Kumar Milind Rewanand , Sundar Sriram , Suryawanshi Saurabh Sanjayrao
Published: February 2023

Systems with combined sliding-rolling contacts such as cam-follower, clutches, and gearbox are prone to have clearance(s) as per the design and/or due to manufacturing imperfections or wearing as a result of sliding between components. This clearance non-linearity results in an impact
between components, which in turn generates a significant rattle during operation. The noise generation mechanism in rattle is a strong function of impact-velocity and contact forces. The objective of this study is to develop an experimental transfer function to quantify the vibro-acoustics
of a cam-follower system with clearance non-linearity. Contact between the cam and the follower is lubricated to minimize the sound generated due to friction. Follower acceleration, reaction forces, and acoustic pressure are measured on a cam-follower setup with combined rolling-sliding contact
during impacts under various conditions. Velocity and contact forces are back-calculated using measured signals and the analytical model dynamics. Transfer functions relating the acoustic pressure to velocity and contact forces are estimated in the frequency domain. These transfer functions
provide insights into the vibro-acoustic system and can be directly used in conjunction with dynamics models. The output of the study can be used in designing quieter systems with impact.
Compact asymmetric treatments for perfect sound absorption in ventilated problems
Authors: Boulvert Jean , Groby Jean-Philippe , Gabard Gwénaël , Romero-García Vicent
Published: February 2023

This presentation introduces compact asymmetric treatments for sound absorption, i.e., simultaneous cancellation of reflection and transmission, in a lined duct of constant cross section. The treatments are composed of side by side and sub-wavelength resonators. They are thus compact,
which facilitates their practical use. The simplest asymmetric treatment is formed by a pair of detuned resonators that can lead to a perfect monochromatic sound absorption. Furthermore, the combination of multiple pairs of resonators generates multiple low quality factor absorption peaks
leading to an absorption plateau. Two compact asymmetric treatments are presented: one is composed of quarter-wavelength porous resonators to prove their ability to achieve perfect sub-wavelength absorption in a duct problem and the other is composed of Helmholtz resonators flush mounted on
the walls of a large cross-section duct. In both cases, the evanescent coupling between the resonators has an important impact on the treatments behavior and is thus accounted for during their optimization. The experimental results are found in good agreement with the theory and a mean absorption
coefficient of 99% over a large target and subwavelength frequency range is observed for each treatment.
ERROR AND UNCERTAINTY IN NEAR-FIELD SOUND POWER ASSESSMENTS OF INDUSTRIAL SOURCES
Authors: Tofts Jon
Published: February 2023

Near-field sound pressure measurements may be converted into sound power levels (Lw) in order to populate propagation models. Although standards exist such as ISO 3740:2019 which present rigorous methods for the accurate determination of sound power levels, complying with such standards
is not always feasible once an industry is operational. In such cases, it is common to see propagation models populated using a sound power estimate from a single field-based measurement. Alternatively, propagation models can be populated using sound power data that have been provided by equipment
manufacturers or that have been presented in other standards such as BS 5228-1:2009+A1:2014. Previous papers commonly consider the isolated uncertainties associated with laboratory-based sound power assessments. This paper will explore multiple sources of error and uncertainty within near-field
sound power estimates from field-based sound pressure levels and will suggest ways to minimise them.
Audio-frequency surface wave characteristics above porous and comb-like surfaces
Authors: Attenborough Keith , Taherzadeh Shahram
Published: February 2023

Part of the solution for the sound field due to a point source in air over a porous boundary has the form of an airborne surface wave. Analytical expressions for the surface wave characteristics are reviewed and corresponding analytical expressions for group speed are obtained from
a thin air layer approximation for the impedance of a comb-like surface, from two approximate models for the acoustical properties of porous media and from a model for identical slanted slit pores. Predictions of absorption coefficient spectra for a hard-backed porous layer with flow resistivity
sufficiently low that there is extended reaction are made using two of the approximate models and compared with those of a relatively exact slanted slit pore model. The model derived specifically to predict the acoustical properties of porous asphalt is found to be the least satisfactory.
The various models are used to obtain analytic expressions for the surface wave group speed. Predictions of surface wave characteristics including group velocity are compared with data obtained over arrays of parallel aluminium strips.
Field-testing of noise abatement measures
Authors: Brick Haike , Böhm Jenny
Published: February 2023

The strengthening of rail transport must be accompanied by a reduction in emissions. Regarding acoustics, innovative measures to increase noise protection must therefore be developed and investigated. Nevertheless, the determination of the sound reduction effect of mitigation measures
on the railway infrastructure or in the propagation path is not yet standardised. There is a need for the development of a measurement and evaluation procedure, which is practice-oriented, reliable and allows the assessment of innovative measures in approval procedures. The German Centre for
Rail Traffic Research (DZSF) at the Federal Railway Authority - an independent, scientific research facility of the German Federal Government - will support these activities. In addition to theoretical investigations, the Open Digital Test Field, which is being set up by the DZSF in the Lusatia
region between Halle (Saale) - Cottbus - Niesky, is available for practical tests. Before starting the field tests, measurement procedure and boundary conditions are to be defined. The requirements and methods for quantifying mitigation measures formulated in previous research projects are
outlined and reviewed. The presentation will discuss a derived proposal and show the selection of acoustic test sections in the Open Digital Test Field that meet the requirements.
Synergetic Effect of Vehicle Interior Sound and Design on Comfortability in Cabin
Authors: Yoshida Junji , Imamori Kanta
Published: February 2023

Vehicle interior noise have been quiet by the development of noise and vibration reduction technique. This noise will become quieter by the engine rest in electric vehicle. Hence, vehicle occupants may expect much more comfort in cabin as if they are in living room. In addition, not
only the auditory stimulus but also visual stimulus is considered to have important role for the comfortability in cabin. In this study, we then focused on the comfortability in cabin and investigated influence of vehicle interior sound and design on comfortability using VR system. In the
test, various virtual interior design and interior sound recorded binaurally at cruising condition were presented in the VR system and the sound, design and total comfortability was assessed through subjective evaluation test. As the result, both sound and design comfort were observed to be
essential to increase the total comfortability and synergetic effect between them was found. This indicates that the influence of sound comfort to total comfortability changes according to the design comfort. Furthermore, soft-smooth interior sound and dark-solid interior design were clarified
to improve the total comfort.
The impact of changing fleet makeup on airline noise emission
Authors: Einicke Karina , Kennedy John
Published: February 2023

With the advent of the Environmental Noise Directive (END) population level modelling of exposure to aircraft noise has increased within Europe. Present noise exposure legislation focuses on airports whereas the greatest potential to implement noise reduction technologies lies with
the airlines and aircraft manufacturers. This work focuses on the modelling the noise emission of the fleet of Europe's largest airline by passenger numbers, Ryanair. The noise reduction achieved at a fleet level will be evaluated and the impact of changing fleet makeup assessed. The airline's
current fleet consists of 409 Boeing 737-800 aircraft and 29 Airbus A320-232 aircraft, while 210 new Boeing 737-8200 max aircraft are on order. The new aircraft have a 40 % smaller footprint in the 85dB(A) noise contour during take-off than the existing 737-800. The 85dB(A) contour of 737-800
stretches out around 4.5km along the runway, while the contour of 737-8200 max was reduced to ca. 2.5km. This is achieved by implementing new winglet design and more efficient power units, which operate with lower fuel consumption (and thus lower aircraft weight), less carbon emissions, and
lower noise emissions. The impact of this change to the fleet is evaluated using a representative airport modelled in SoundPLAN. Noise contours generated with SoundPLAN show the noise effects of the different aircraft types of the historic, current and future Ryanair fleet under realistic
operating conditions. Different departure profiles are investigated, depending on the aircrafts weight, altitude, speed, and thrust profile. The generated noise contours provide an evidence base for decision making within the airline for investments aiming to reduce noise levels around airports.
The potential for reducing population exposure to noise under the framework of the END is presented.
What is a soundscape intervention? Exploring definitions and identification criteria and a platform to gather real-world examples
Authors: Moshona Cleopatra , Aletta Francesco , Henze Helen , Chen Xiaochao , Mitchell Andrew , Oberman Tin , Tong Huan , Fiebig André , Kang Jian , Schulte-Fortkamp Brigitte
Published: February 2023

Possible definitions for the concept of "soundscape intervention" and criteria that could be used to identify stages in a design-oriented framework are discussed. This is in line with the Part 4 of the ISO 12913 series on soundscape being currently developed. The long-term
goal is observing frequent/recurring situations or strategies that can be collated into design toolkits and formulate design briefs that local authorities will be using to communicate with soundscape consultants. For some time already, the soundscape concept has attracted attention from policy-makers
and practitioners of the built environment, as it advocates for more engagement with local communities in design processes. This is reflected in several documents published by national and international agencies calling for consultation and participation of the public in the definition of
soundscape interventions. However, this intended framework did not really make any significant breakthrough in the planning and design community, possibly for the lack of conspicuous empirical evidence (i.e., case studies and success stories) showing the benefits provided by the soundscape
approach, and some lack of consensus about what a "soundscape intervention" is in the first place. Therefore, an online platform will be presented that can be used for data collection of soundscape intervention examples.
Wind turbine noise emission: comparison between measurement results and propagation model
Authors: Bevilacqua Antonella , Iannace Gino , Lombardi Ilaria
Published: February 2023

Wind energy is a valid alternative resource in place of fossil fuel to produce electricity, representing also a great contribution to reduce atmospheric pollution. This paper deals with some concerns related to the construction and management of wind farms, by including the negative
effects produced on the avifauna and the landscape as a visual impact other than the effect of electromagnetic pollution. On this basis, some model simulations have been undertaken on the sound propagation produced by wind turbines whose results have been compared to the measurements taken
inside the closest sensitive receptor. The noise generated by the operation of the towers causes a significant annoyance to residents living in the surrounding areas. The data recorded inside the selected residential properties have been analyzed by highlighting a tonal characteristic although
the measured sound levels are up to 50 dB(A). Additionally, a comparison between the results obtained by model simulation and by site measurements has been performed.
Sound isolation via temporal modulation material based on piezoelectric elements
Authors: Liu Xiang , Wang Chunqi , Zhang Yumin , Wu Keming , Huang Lixi
Published: February 2023

The temporal modulation material is investigated to be used as lightweight sound isolation material. This smart composite material consists of a lightweight structure attached with shunted piezoelectric ceramic (PZT) patches. The shunt circuits are connected to the two poles of PZT
patches to act as some local electrical resonators to improve the sound isolation. The circuit is composed of operational amplifiers and passive analog circuit elements, so the system is always stable, and the power consumption is low. The metal-oxide-semiconductor field-effect-transistor
(MOSFET) is added in the shunt circuit connected to the PZT patches, so the time sequence of the working circuit is controlled with the MOSFET devices in each resonant shunt. The motivation of this study is to improve the sound isolation in the low-to-middle frequency range. The temporal modulation
material proposed in this study has many potential applications in environmental acoustics, precise instrument, automotive sector, and aerospace technologies.
A key physical mechanism that controls the sound absorption of aerogel powders
Authors: Horoshenkov Kirill , Xue Y , Bolton S. , Horoshenkov K.V.
Published: February 2023

A key physical mechanism that controls the acoustic absorption and attenuation in a loose, air-saturated aerogel granular mix with the grain diameter being in the order of a few microns is not well understood. A particular challenge here is to understand sound propagation in an aerogel
powder composed of highly porous, low-density particles with sub-micron pores. Experimental evidence suggest that a relatively thin layer of an aerogel powder can provide a very high narrow band acoustic absorption at relatively low frequencies. This study presents an attempt to explain this
physical phenomenon with two well-known analytical models for the acoustical properties of porous media. The results of this study suggest that an aerogel powder behaves like a viscoelastic layer and its absorption coefficient depends strongly on the sound pressure level in the incident wave,
i.e., this acoustic behaviour is non-linear. The loss factor seems to be a key parameter which predicts the observed acoustical behaviour. The loss factor is found higher than physically reasonable at low frequencies and decreases with the frequency exponentially. This behaviour is likely
to relate to the frictional interaction between the particles in the powder and acoustic fluoridisation effect.
A sound from the arena: acoustic reconstruction of a Roman amphitheater located in Avella, south of Italy
Authors: Bevilacqua Antonella , Iannace Gino , Lombardi Ilaria , Parente Rosaria
Published: February 2023

In the ancient Rome the shows entertained by gladiators were very numerous, due to the always growing request from the spectators. After the disuse of the amphitheaters, a wide number of philosophers, writers and poets have been experienced to say what happened in these arenas. Nowadays
this type of shows represents continuous source of inspiration for different books and movies (e.g. The gladiator, Spartacus). The amphitheaters are characterized by having an elliptical plan layout, which allow to enlarge the capacity of seats other than improving the sight from the steps
of the cavea. The most famous Roman amphitheater is the Colosseum with its biggest dimensions that only the capital city of the empire could have, followed by others of smaller volume size. The development of Christianism decreed the immorality of these shows while the barbaric invasions contributed
to convert these places into military barracks, if they were not selected to be demolished. This paper deals with the acoustic study of the amphitheater of Avella, which has been found only a few decades ago by archaeological excavations. The geometrical characteristics are typical of other
amphitheaters built in Campania during the Imperial age. An acoustic survey has been undertaken in order to understand the main acoustic parameters in accordance with ISO 3382-1, given the functionality of this place in hosting musical shows during the summer seasons. Based on historical sources
and discoveries, a virtual model has been realized to represent the architectural features of how the amphitheater would be looked like originally. The model has been used for acoustic simulations by applying the absorption and scattering coefficients of the finish materials, and the results
have been assessed to highlight the different acoustic perception between the existing conditions and the original shape.
Collecting and mapping soundscape data across the 15 UK national parks
Authors: Oberman Tin , Stollery Peter , Aletta Francesco , Kang Jian
Published: February 2023

The soundscape approach, as understood by the ISO 12913 series, is most applied in urban settings, aiming beyond noise control in order to holistically employ its quantitative and qualitative facets. On the other side, the current understanding of the soundscape concept in bioacoustics
and acoustic ecology is less focused on perception. There is generally a lot of public interest in how to preserve the opportunity for people to experience the "natural quiet" and "the sounds of nature", and the need to balance that with the protection of the natural areas
and national parks from the noise that the visitors themselves generate while on site. However, specific investigations in these environments are scarce in the UK. Moreover, while there might be acoustic environments and sound sources that people identify with national parks, they are not
systematically documented nor implemented in the national parks' management plans. Therefore, we propose a framework starting with a quasi-crowd-sourced acquisition of soundscape data and mapping those to a freely accessible GIS platform such as Google Earth, leading towards identifying soundscape
conservation targets and management tools for the UK national parks, further raising the awareness of the value of sound as a resource.
The Sonic Identity Model: one interdisciplinary approach for qualitative urban soundscape analysis, management and design
Authors: Gleeson Sophie
Published: February 2023

Urban soundscapes are predominantly understood through the use of quantitative environmental noise management and traditional acoustic design approaches. These approaches, while valuable, do not capture the subjective qualities of sonic environments as experienced by its users. The
Sonic Identity Model, developed by Pascal Amphoux of the Centre for Research on Sonic Space and Urban Environment (CRESSON), offers one interdisciplinary approach for qualitative urban soundscape analysis, management and design. The interdisciplinary Model is intended to be used by large research
teams to study a city's soundscape. Since its publication in 1993 it has received little attention in urban soundscape research and practice. In this paper I provide an introduction to, and overview of, the Sonic Identity Model. I review practitioner uses of the Model, with a focus on its
demonstrated applicability in conjunction with traditional acoustic design approaches. I then present my contemporary adaptation of the methodology, developed for individual researchers to study indoor and outdoor urban soundscapes in situ, and describe its use in a limited urban study. This
paper serves to position the Model as a guiding framework for future urban soundscape practice, offering practitioners a toolkit of qualitative methods for soundscape documentation and conceptual tools for soundscape analysis.
Prediction of combustion noise for a swirling flame with low order network model
Authors: Hongzhi Zhu , Min Zhu
Published: February 2023

Combustion noise has become an important noise source for gas turbines and aero engines. Efforts are needed in understanding mechanisms of combustion noise and developing prediction methods. In this work, direct combustion noise for a swirling premixed flame is predicted by low order
model (LOM) and compared with experiments. In LOM, model combustor is simplified to a plenum, a swirler and a combustion chamber. Unsteady heat release rate is set to a constant value and pressure perturbation is calculated. Thermoacoustic transfer function defined by the ratio of pressure
perturbation and unsteady heat release is calculated to describe noise spectrum distribution. Results show that peaks in thermoacoustic transfer function increase with the gain of downstream reflection coefficient while corresponding frequencies maintain unchanged. The phase of downstream
reflection coefficient affects both peak frequency and amplitude. In experiments, unsteady heat release and pressure perturbation are measured. Thermoacoustic transfer function calculated by experimental results presents several peaks associated with thermoacoustic instability modes. With
proper reflection coefficient, predicted thermoacoustic transfer function is compared with experiments and achieves reasonable agreement. Thermoacoustic transfer function provides a basic understanding for energy transfer from heat release to acoustic waves and could be used to predict combustion
noise.
Fine tuning topological waveguides using asymptotic analysis
Authors: Davies Bryn
Published: February 2023

We use asymptotic methods to quantify the properties of topological waveguides and show how these concise results can be used very efficiently to design materials with specific, custom specifications. This work uses a general method that we recently developed for studying localised
eigenmodes in periodic media with defects. The results of this analysis characterise the existence of localised eigenmodes, determine their eigenfrequencies and quantify the rate at which they decay away from the defect. These results are obtained using both high-frequency homogenisation and
transfer matrix analysis, with good agreement between the two methods. This approach is ideally suited to studying problems arising in topological wave physics. We demonstrate the efficacy of our approach by studying materials based on the Su-Schrieffer-Heeger model (a simple example of a
one-dimensional crystal supporting topologically protected modes). We show that our theory accurately predicts the localised eigenmodes and we use it to design rainbow devices that separate frequencies according to custom requirements.
Study on the correlation between noise perception and annoyance level of residents in residential areas along the tracks
Authors: Ma Jinglun , Wu Yue , Meng Qi
Published: February 2023

Noise has gradually become a key problem that cannot be ignored in urban environment. In recent years, with the rapid development of railway transportation in China, the sound environment of residential areas along the track is very complex, among which the noise and vibration brought
by train running will affect human health. Therefore, this study adopts the subjective evaluation method to conduct a questionnaire survey on the sound environment of residential areas along the track, and studies the correlation between residents' noise perception and annoyance level. The
results show that there is a strong correlation between noise perception and annoyance (p<0.01).In addition, noise perception and annoyance level are significantly different between daytime and nighttime. It is found that the sensitivity and annoyance level of railway noise in daytime are
lower than those in night. The above results may be due to the masking effect of residents' activities and road noise on railway noise during daytime, which reduces the perceptual sensitivity of railway noise during daytime. The results can provide guidance for setting noise limits of railway
running in different periods.
Characterisation of time-varying structure-borne sound sources using a reception plate to predict maximum Fast time-weighted levels in heavyweight buildings
Authors: Reinhold Steffi , Hopkins Carl
Published: February 2023

Structure-borne excitation from many mechanical appliances leads to structural vibration which can be transmitted to nearby rooms and cause annoyance for building occupants. The reception plate method provides a simplified characterisation procedure to obtain the power input for SEA
prediction models. Empirical corrections based on the relationship between Leq and LFmax are introduced to predict sound transmission from time-varying source vibrations in buildings. For this purpose, the reception plate method is used to capture the maximum power input. Using different ramped
noise signals as idealised versions of time-varying signals from machinery has allowed empirical corrections to be identified such that short Leq measurements can be used with the reception plate. When using SEA or EN12354 it is shown that LFmax in a room can be predicted for a time-varying
structure-borne sound source with one-third octave band errors within ±3 dB. Similar results occurred for predicted LAFmax levels calculated from frequency-dependent A-weighted LFmax. A case study with a toilet flush was performed on the reception plate to replicate the empirical corrections
derived from ramped noise signals which resulted in close agreement.
Influence of Structural Form on the Acoustic Black Hole Array Coupled with Damping Layers
Authors: Yao Zhengcheng , Liu Xiandong , Bao Yue , Liang Haoming , Shan Yingchun , He Tian
Published: February 2023

Because of the characteristics of manipulating bending wave, acoustic black hole (ABH) structures can efficiently concentrate vibration energy in the center. Other than single ABH structures, the ABH array or damping layers can be used to have a better performance in vibration reduction
and noise control, which have great engineering application prospects of plate parts. In order to explore the influences of ABH array on vibration and noise reduction, finite element models of two-dimensional ABH array coupled with damping layers were established in this paper to study the
effects of arrangements and number of ABH cells on dynamic characteristics. Firstly, this paper analyses the influences of array embedded with three ABH cells on the modal loss factor and vibration characteristics of the structures as well as the effects of different arrangements. Secondly,
the array with different number of ABH cells were established to study the effects of the number of elements on the vibration response of the plate. Finally, the structure-sound coupling models were established to study the acoustic radiation characteristics and explain the noise response
of the array plate. This study provides a reference for the design and application of the plates embedded with ABH array.
Effect of the microstructure on the acoustic performance of porous material liner in the duct
Authors: Song Xiang , Xu Jingjian , Yuan Tianyue , Sui Dan , Xiao Heye , Zhou Jie
Published: February 2023

Acoustic liners can efficiently reduce the sound pressure level in the duct. The porous material liner has recently received wide attention for the excellent attenuation performance at mid- to high- frequencies. However, more attention was paid to the sound attenuation of the given
porous material liner in the duct rather than the design of the porous material liner for a duct noise problem. In this work, from a micro perspective, the influences of the average fiber radius and gap of the porous material liner on the acoustic field in a duct are systematically analyzed,
based on the bottom-up method and Johnson-Champoux-Allard model. The multimodal method is utilized to evaluate the duct acoustic field. The work may guide the selection and design of the porous material during the application of the porous material in the duct noise problem.
Generation and Analysis of Artificial Warning Sounds for Electric Scooters
Authors: Torija Martinez Antonio J , Elliott Andrew , Harris Lara , Podwinska Zuzanna , Welham Connor
Published: February 2023

Micro-mobility transportation, including electric scooters and e-bikes, could bring substantial benefits to resolving road congestion, provide an eco-friendly transportation system, offer low-cost personal transportation, and increase accessibility. Another benefit is that electric
scooters are very quiet, only producing some minimal rolling noise and high frequency emission due to electric motors. Quietness of the vehicles has led to safety concerns being raised by accessibility groups, such as the Royal National Institute of Blind people (RNIB). For this reason, we
have teamed up with the RNIB to explore, well-designed Acoustic Vehicle Alerting Systems (AVAS) as a potential solution to ensure vehicle detection and avoid potential conflict with pedestrians. This paper presents the key findings of a research project carried out by the University of Salford's
Acoustic Research Centre, in collaboration with Dott Scooters and RNIB. The goal of this project was to develop a stand-alone warning sound system for electric scooters, with the main constraint of ensuring an appropriate balancing between vehicle awareness and noise annoyance. Based on preliminary
results, this project concluded that a significant benefit, in terms of vehicle noticeability, is observed with the addition of a warning sound. Funding has been secured to carry out further research to optimise the AVAS for complex urban environments.