bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Pure Tone Audiometry and Otoacoustic Emission based Hearing Assessment for Classical Music Students
Authors: Zepidou Georgia , Dance Steve
Published: February 2023

Since the enforcement of the Control of Noise at Work Regulations research has been undertaken in collaboration with the Royal Academy of Music investigating the hearing acuity of more than 5000 students between 2007 and 2021. Standard pure tone audiometric screening methods were employed
for both entry and exit testing of undergraduate and postgraduate students. The results of these investigations have informed a pilot study, ran in September 2021, comparing two hearing health surveillance methodologies: pure tone audiometry and otoacoustics emissions involving 256 classical
music students. This comparison was necessary as music students had been found to be able to game the Bekesy test procedure as a result of their acute listening ability. The results showed that otoacoustic emissions were able to identify, at an early stage, hearing damage in an additional
3.8% of students. The test procedure itself was found to be quicker, more convenient and offered greater objectivity without learning bias. This provides reassurance that otoacoustic emissions can be an excellent tool for assessing the hearing health of classical music students and identifying
hearing damage at an early stage.
Occupational noise legislation in Asia-Pacific region
Authors: Yokoyama Sakae , Kobayashi Tomohiro
Published: February 2023

To prevent hearing loss for workers exposed to intense workplace noise, occupational noise laws have been enacted in many countries. However, for the legislations on occupational safety and health in Europe and the Americas, it seems that "permissible exposure limit (PEL: 8-hour
average)", "exchange rate (ER)", "upper limit of impact noise", and other requirements for occupational noise exposure are not unified at present. On the other hand, few reports have been published in English on laws and regulations related to occupational noise in
the Asia-Pacific region. Therefore, in this paper, the outlines of PEL, ER, " upper limit of impact noise ", "wearing personal protective equipment", " audiometric test request", "penalties", etc. for occupational noise in the Asia-Pacific region were
summarized. As in Europe and the Americas, many countries of the investigated Asia-Pacific region use 85dBA or 90dBA PELs, 3dB or 5dB ERs and upper limit of 140 dB(C) for impact noise.
Sound propagation for a low height impulsive source over an absorbing ground
Authors: Van Der Eerden Frits , Van Den Berg Frank , Van Heijningen Ad
Published: February 2023

Noise contours around military training areas are calculated by using: a) the measured source strength for the impulsive sources and b) the calculated sound propagation using a representative set of meteorological situations. For high-energy impulsive sounds the source strength is measured
at distances beyond 100 meters, where peak levels are below 154 dB. A linear model is used to correct for the sound propagation from the source to the measurement position. In this way a linear source strength is determined that can be used with linear sound propagation models. Previous results
showed that the source strengths at higher frequencies (above 250 to 500 Hz) were overestimated when the impulsive source is on the ground. Apparently, the calculated sound propagation over an absorbing ground, used to determine the source strength, is accounting for too much ground effect.
Note that the actual meteorology and ground absorption are measured during the measurements. In this paper an impulsive reference source is used at two heights and the sound propagation is measured and calculated at increasing distances. It is shown that the measured ground effect saturates
for higher frequencies. Next, an unknown impulsive source was measured and the effect of saturation was demonstrated.
Intrinsic thermo-acoustic instability criteria based on frequency response of flame transfer function
Authors: Kojourimanesh Mohammad , Kornilov Viktor , Lopez Arteaga Ines , de Goey Philip
Published: February 2023

The study of Intrinsic Thermo-Acoustic (ITA) instability behavior of flames anchored to a burner deck is performed by introducing a mapping between the Flame Transfer Function, FTF(s), defined in the complex (Laplace) domain and experimentally measured frequency response, FTF(iω).
The conventional approach requires a system identification procedure to obtain the FTF(s) from the FTF(iω); next, root-finding techniques are applied to define the complex eigenfrequencies. The purpose of the present work is to establish instability criteria which are directly applicable
in the frequency domain. The particular case is considered when the acoustic boundary conditions at both sides of the flame are anechoic. At first place, the causality of the measured FTF(iω) is checked. Then, the criteria of the ITA mode instability applicable to the FTF(iω) phase
and magnitude, are derived. Cauchy's theorem and the path-independence Lemma are used to find the scaling factor of the mapping which allows to determine bounds of the unstable frequency and the maximum value of the linear growth rate. The proposed method is applied to study the behavior of
burners with premixed burner-stabilized Bunsen-type flames. The comparison of the measured oscillation frequencies and the growth rates of observed unstable oscillations with that obtained from the derived bounds reveal good correspondence.
Influence of Environmental Sensitivity on Soundscape Evaluation in Urban Open Public Spaces
Authors: Gao Weifu , Kang Jian , Ma Hui
Published: February 2023

Urban open public spaces play a vital role in contemporary cities, and the quality of the soundscape in these environments affects people's psychological and physiological restoration. Previous soundscape research has shown that environmental sensitivity is a crucial factor affecting
psychological responses to the acoustic environment, but many of these findings are restricted to the interpretation of "negative" dimensions' variance of evaluations. In this experiment, we examined the effects of individuals' different aspects of environmental sensitivities such
as vulnerability sensitivity (noise sensitivity, etc.) and vantage sensitivity (aesthetic sensitivity, etc.) on soundscape evaluation through experiencing audio-visual environments of various urban open public in laboratory. The participants, 20-45-year-old college students and staffs with
normal hearing (N=30), experienced ten common urban open space scenarios (parks, plazas, pedestrian streets) for at least 10 minutes each, and finished the questionnaire which consisted of two parts: items from the Soundscape Quality Protocol and the Environmental Sensitivity Survey includes
Weinstein's Noise Sensitivity (WNS) Scale and Highly Sensitive Person (HSP) Scale. The results show that people with high noise sensitivity tended to overestimate the "negative" dimensions of soundscape evaluations, whereas people with high aesthetic sensitivity tended to overestimate
the "positive" dimensions. These environmental sensitivities were found to be statistically independent. In other words, environmental sensitivity affects the soundscape evaluation significantly in urban open public spaces. This suggests that attention should be paid to the diverse
needs of different people, in policy-making and urban planning.
Comparison of the direct sound insulation for wooden joist, CLT and timber hollow box floors
Authors: Homb Anders , Conta Simone
Published: February 2023

Timber buildings are now present worldwide, and their market is growing rapidly, pushed by sustainability and environmental arguments. Several technological options for engineered wood systems are available and well developed, the most common being wooden joist, CLT and timber hollow
box. In this paper, we present a comparative study of the airborne and impact sound insulation of the three options. The analysis is based on data collected from laboratory measurements. The results include the comparison of the bare floor construction and examples of assemblies with additional
floating floor, suspended ceiling or a combination of the two. We identify the characteristic trends and highlight the effect of selected parameters as for instance mass per unit area, assembly thickness and properties of the resilient layers. The comparison attempts to show the constructive
consequences of the different options on the sound insulation properties. It could help selecting the most suitable floor system in future projects and contribute making timber construction more efficient and affordable.
Reflections on an EDI Survey of UK-Government-Funded Research Networks in the UK
Authors: Chandler-wilde Simon , Fearnshaw Debra , Fisher Oliver , Jones Eleri , Kanza Samantha
Published: February 2023

We discuss the results of a Community EDI Survey run in July-September 2021 by the Network of Networks, a union of research networks that are largely funded by the UK Engineering and Physical Sciences Research Council and fall under their remit. Responses were received from members
of 19 networks, with, relevant to this meeting, 70% of the 267 responses coming from members of the UK Acoustics Network. We discuss implications of the results for how we organise and support attendance at events across our networks, reflecting on feedback to questions on barriers and possible
enablers to attending in-person events, and on feedback as to what does and doesn't work for events blending in-person and online attendance. To put this work in context we survey relevant literature on the value or otherwise of blended and online events for supporting the diverse membership
of a network. The survey results also provide interesting feedback on the diversity of our networks and how inclusive our networks are perceived to be as a function of the identity of the respondents. We reflect also on lessons from this experience regarding how and how not to attract a strong
response to surveys of this type.
Finite element analysis of bending waves in Mindlin plates with Perfectly Matched Layers
Authors: Cao Da , Inoue Naohisa , Sakuma Tetsuya
Published: February 2023

It is important to determine the boundary conditions of walls and floors precisely when simulating the building acoustics. For a certain room, the extension of the spans can be considered as infinite edges. The Perfect Matched Layer(PML) is an artificial absorbing domain for the wave
propagations and is widely used in finite element analysis to simulate the acoustical free field conditions right now. In this paper, an effective PML technique for the plate structure will be presented. The PML formulation will be derived based on the Mindlin plate theory and the implementation
method will be introduced. This technique will be validated through the numerical experiments. The accuracy and limits of the presented technique will be discussed based on the numerical results compared with the analytical results. The results show that the presented PML technique is effective
and accurate to simulate the plate as an infinite large plate. It is expected to implement the technique in the further research of the structure borne sound, such as floor impact sounds.
Narrowing the Knowledge Gap When Teaching the Theory of Acoustics for Higher Education
Authors: Prokofieva Elena
Published: February 2023

In many academic institutions across UK it is currently popular to offer the higher education degrees to the people who are working in industry. The students are able to develop the industry skills in their job whilst studying for a university degree. For people working in audio industry
or in building acoustics, it is highly beneficial to their day-to-day jobs that they will become educated on the theory of acoustics. When teaching at the graduate apprenticeship scheme, or the higher education diploma in acoustics, it is always important to study what is the background of
the individual students. If the group of students has mixed educational/ experience backgrounds, the strategy of teaching the theory of acoustics has to be re-developed by the tutor to ensure the maximum involvement of the students as a group, as well as to include the purpose-built individual
exercises for the students who need an additional support. The examples of the strategy evolvement would be demonstrated. It is important that the tutors either know engineering subjects or are adaptive to learn quickly to be able to accommodate the needs of the industry and the desire of
the students to study.
Experimental setup for laser vibrometry measurements of the vibrating horn in Ultrasonic Metal Welding
Authors: Abi Raad Elie , Müller Florian W. , Reisgen Uwe , Vorländer Michael
Published: February 2023

Ultrasonic Metal Welding is a type of welding used in the production of electric car batteries. Currently, it suffers from quality fluctuations, and there is a need for online quality control techniques. One technique being investigated involves the measurement of the vibrations of
the welding horn using laser vibrometry. However, this comes with two obstacles. First, measurements close to the welding site, which contain the most information, are difficult to do. This is due to the interference of particles ejected during welding, which interfere with the laser beam.
Second, it is possible that the use of reflective tape for vibrometry changes the vibrations measured, due to heating of the horn during welding. This work investigates these problems and presents some solutions. The effects of the reflective tape on the measurement is investigated, by measuring
the vibrations of the horn during welding and free run, with and without reflective tape, and with and without prior heating of the tape. Furthermore, the interference of ejected particles is minimized using a special experimental setup, and measurements are done without any reflecting tape.
Beyond Standards: In Search of Heterogeneous Approaches to Sound in the Design and Planning of the Public Realm
Authors: Anderson Sven
Published: February 2023

The public realm constitutes the integral connective tissue that defines the contemporary cityscape, within which different individuals, communities and institutions engage with each other through cooperation and negotiation. Sound remains a neglected dimension of this domain, generally
coming into consideration only through efforts to ameliorate the urban soundscape and to attend to the impact of environmental noise. As the densification of urban territories continues, the role of sonic experience as a more critical and complex driver for urban design must be reassessed.
The project Sound-Frameworks: Collaborative Frameworks for Integrating Sound Within Urban Design and Planning Processes (EC grant agreement ID 101032632) explores new methodologies to accelerate this area of research through the production of three resources: A sound in practice survey, a
publication on guidelines for best practice and an online tool to guide the integration of sound in the design of the public realm. This paper discloses the project's initial trajectory and intersectoral objectives. It explores how the synthesis of heterogeneous approaches to working with
and thinking through sound can be informed by perspectives developed through environmental acoustics, architecture, spatial planning, sound studies and artistic practice.
Public address and sound emission by an active noise control system in ventilation duct networks
Authors: Lesoinne Stephane
Published: February 2023

In a ventilation duct network, two types of silencers can be used: passive (medium and high frequencies) and active (low frequencies). Active silencers have a loudspeaker (control loudspeaker) that generates an anti-noise. Usually, this system is placed close to the fan and far from
the duct air opening. However, when the system is placed close to an air opening, the control speaker can not only be used to reduce the fan noise, but also as a background speaker to play music, information, alerts (the target signal) ... This concept has been implemented in an active noise
control (ANC) system based on the adaptive feedforward normalized FxLMS algorithm which uses a reference and an error microphone to pick up respectively the noise to attenuate and the residual noise after control to be minimized. The algorithm is modified so that the target signal does not
contaminate the reference nor the error signals. The new algorithm is tested in real time in a short duct with different type of noises and target signals.
Sound Radiation from a Plate with Embedded Active Acoustic Black Holes
Authors: Hook Kristian , Cheer Jordan , Daley Stephen
Published: February 2023

Acoustic Black Holes (ABHs) can be realised as tapered structural features that focus and absorb vibrational energy. In a plate, the damping effect of ABHs can be used to reduce the radiation efficiency, particularly above the critical frequency of the plate. However, at lower frequencies,
there is still significant radiation due to the low order modes of the plate. It has previously been shown that the combination of active control and ABHs can result in an effective broadband control solution with lower computational and power requirements compared to a standalone active configuration.
This paper presents an investigation into how two different active control strategies affect structural response and radiated sound power of a plate with active ABHs (AABHs). It is shown, through an active vibration control strategy and an active noise control strategy, that the AABHs can
be used to successfully control either the global structural response of the plate or the radiated sound power. However, it is also shown that controlling either response can lead to an enhancement in the other.
Acoustic Black Holes in Curved Plates
Authors: Hook Kristian , Cheer Jordan , Daley Stephen
Published: February 2023

Acoustic Black Holes (ABHs) have been shown to produce significant vibration damping in both beams and flat plates. However, it is interesting to determine how more complex structures with singularly curved surfaces are damped by the addition of ABHs. Therefore, this paper presents
an investigation into three different ABH designs that can be implemented into a curved plate. The performance of each ABH design is compared in terms of the global structural response of the curved plate.
Developing a holistic tranquillity assessment method from a soundscape design approach
Authors: Thomas Adam , Owen David , Drysdale Sarah
Published: February 2023

The assessment of tranquillity considered in Environmental Impact Assessments does not currently benefit from a single 'industry accepted' multidisciplinary approach. Current assessments rely mainly on objective measurements of imagery, sound, and investigator expert opinion. These
approaches do not fully consider the context of the site, the interaction between different environmental disciplines or the perceptual aspects of Tranquillity. Standardised soundscape methodologies (ISO12913-2:2018) are now used to measure perception of acoustic environments in context. This
study explores a soundscape approach to tranquillity assessment of heritage assets. Is it possible to develop a holistic assessment method based upon the data collection methods of soundscape principals of ISO 12913-2:2018 that is robust, scalable and applicable to the methods of assessment
used within the built environment? Existing research on attention restorative theory is used to identify a set of attributes for use in a Soundwalk questionnaire. The methodology is tested by the authors conducting a Soundwalk at a set of heritage locations located within the Knowledge Quarter
of London. The findings are supportive with recommendations for further development of the method that could involve different stakeholders that have local expertise and governance.
Subjective evaluation of the acoustic annoyance in a large passenger aircraft cabin
Authors: Lv Bingcong , Huang Yu , Jiang Weikang
Published: February 2023

People demand better acoustic comfort for higher travelling quality and security in aircraft. It is necessary to evaluate and predict the subjective annoyance caused by the noise in aircraft cabins. This study investigates the noise-induced annoyance in a large passenger aircraft. We
recorded the noise at 21 positions in the aircraft cabin without passengers and selected 21 stimuli during the cruising. Each stimulus has a duration of 5 seconds and a sound pressure level in the range of 72-81dB(A). The psychoacoustic parameters such as loudness, sharpness, roughness and
articulation index were also calculated. Twenty-four subjects evaluated the subjective annoyance of the stimuli by the absolute magnitude estimation method. Results showed the noise annoyance at the middle section of the cabin is significantly higher than that at the front or rear section.
The principal component analysis and correlation analysis found that annoyance is mainly affected by loudness, sharpness and roughness and dominated by loudness. We proposed a multiple linear regression model between the subjective magnitudes of annoyance and the psychoacoustic parameters
to evaluate and predict the noise annoyance in the aircraft cabin well.
Strategic Noise Mapping in France to 2023: Coupling a national database with the open-source model NoiseModelling
Authors: Aumond Pierre , Cariou Sophie , Chiello Olivier , Ecotière David , Le Bellec Adrien , Maltete Damien , Marconot Claire , Fortin Nicolas , Palominos Sylvain , Petit Gwendall , Picaut Judicaël
Published: February 2023

The Environmental Noise Directive (END) requires the realization of strategic noise maps, every 5 years, in order to evaluate the noise impact of roads, railways, airports and the main industries on the inhabitants. To achieve round 4 for major roads and major railways, France has decided
to create a national database called PlaMADE, which gathers all the necessary input data (traffic, building, population, relief...) in a unique format, a COVADIS GeoStandard. On the basis of these data, and using the open-source noise propagation calculation tool NoiseModelling, all the indicators
and maps have been produced for the first time in an automatic way at a national scale. This paper presents the technical and methodological details of the coupling between the PlaMADE database and the NoiseModelling tool.
Nonlinear characterization of azimuthal combustion instability exhibiting flame transient phenomena
Authors: Mohan Balasundaram , Mariappan Sathesh
Published: February 2023

This article characterizes the nonlinear features observed in an annular combustor exhibiting self-excited azimuthal thermoacoustic instability. The annular combustor consists of 12 burners with flames stabilized by bluff bodies protruding into the combustion chamber. This burner configuration
closely resembles the flame stabilization geometry and flame shape in ramjet and afterburners configurations. As a first step, two different bluff bodies stabilize the flame: 1) circular and 2) conical and associated instability dynamics are characterized. The combustor exhibits intermittent
oscillation in pressure with dominant 1A-1L (first azimuthal - first longitudinal) acoustic mode at about 630 Hz. The duration of periodic oscillation in the intermittent pressure fluctuation varies non-monotonically with the airflow rate. Further, relatively large amplitude pressure fluctuations
are observed for intermediate values of airflow rate in both flame stabilization. During these large-amplitude pressure fluctuations, localized flame extinction in certain burners is observed, leading to partial blow-off operation of the combustor. This localized flame extinction is subsequently
followed by either successful or unsuccessful re-ignition, leading to introduction of slow time scale heat release rate modulation in the problem. Further, this slow time scale heat release rate modulation is stochastic, contributing to the appearance of intermittent oscillation in pressure.
Wind turbine noise modeling including aeroacoustic sources and propagation effects: comparison against field measurements
Authors: Mascarenhas David , Cotté Benjamin , Doaré Olivier , Ecotière David , Guillaume Gwenaël , Gauvreau Benoit , Schmich-Yamane Isabelle , Junker Fabrice
Published: February 2023

The study of wind turbine noise and its impact is of growing importance with the increase in the demand for green and clean energy. As it is known that wind turbine noise can be a cause of annoyance in the vicinity of wind farms it is beneficial to predict with certain accuracy the
generated noise in the design phase itself. A crucial step is the validation of prediction models against field measurements (in-situ). This article presents a wind turbine noise prediction model that combines Amiet's theory to calculate trailing edge noise and turbulence interaction noise
in free field with a wide-angle parabolic equation valid in moving media to account for the long-range acoustic propagation effects. The model considers the wind turbine as an extended noise source and the rotation effects (such as the convective amplification and Doppler effect) are taken
into account. The predicted noise levels are compared to those obtained from a measurement campaign where acoustic, meteorological and ground impedance data have been recorded simultaneously. First, the sound source model is validated close to the wind turbines for different wind speeds and
directions. Then, noise predictions are compared to SPL measurements at various distances from the sound source, between 350 and 1300meters.
Self-tuning vibration control using piezoelectric patches and RL shunts set to maximise electric power absorption
Authors: Rodrigues Gabriel , Gardonio Paolo , Dal Bo Loris , Turco Emanuele
Published: February 2023

This paper presents experimental results on the flexural vibration response of a thin plate structure subjected to a stochastic disturbance. The plate is equipped with five piezoelectric patches connected to shunt circuitry to reduce the resonant response of a target flexural mode.
The shunts are synthesized digitally to mimic a resistor-inductor connected in parallel. Firstly, the study assesses the vibration control effects produced by the shunts, contrasting the time-averaged flexural kinetic energy of the panel and the time-averaged electric power absorbed by the
shunts filtered in a narrow band centred on the resonance frequency of the target mode. This analysis shows that both cost functions results on the same optimal tuning parameters, which provides a benchmark for the vibration control. Next, it investigates the online tuning of the resistive
and inductive components of the shunt by implementing an extremum seeking algorithm set to maximise the time-averaged electric power absorbed locally by the shunt filtered in a narrow band centred on the resonance frequency of a target mode. The study shows that indeed the resistive and inductive
components in the shunts connected to the five patches converges to the optimal values with the application of extremum seeking algorithm and this leads to a minimisation of the spectral flexural response vibration at the resonance frequency of the target mode by 18 dB.
Relationships between loudness and preference judgments for fan sounds as a function of the reference sound pressure level
Authors: Claaßen Eike , Töpken Stephan , van de Par Steven
Published: February 2023

In a prior study, the level of fan test sounds was adjusted in a listening test using an adaptive procedure, until they became equally loud or equally preferred as a reference sound at a fixed level. Depending on the test sound, level reductions of up to 15 dB compared to the 60 dB(A)
reference level were necessary to reach equal loudness or preference compared to the reference sound. It turned out that the preference-equivalent levels were highly correlated with the loudness-equivalent levels, indicating that the preference decision and the loudness judgment were closely
related to each other. In a follow-up study, the measurements were extended towards a higher reference level of 75 dB(A) and a lower reference level of 45 dB(A). The preference-equivalent levels obtained at 75 dB(A) were again closely related to the loudness-equivalent levels. For the lower
reference level of 45 dB(A), the preference-equivalent levels deviate from the loudness-equivalent levels by 3.5 dB on average and also the inter-individual variability increased. This result suggests an increasing effect of additional fan-noise characteristics to play a role for the preference
decisions on top of the perceived loudness especially at low absolute sound pressure levels.
Tyre/road noise measurements on ISO tracks using the modified CPX method
Authors: Mioduszewski Piotr , Berge Truls
Published: February 2023

Tyre rolling noise test method specified in the UNECE Regulation 117 is directly used in the Tyre Labelling Directive. Noise level specified on EU Tyre Label of each new tyre available on the European market was determined based on vehicle coast-by noise measurements performed on the
standard reference road surface proscribed in the ISO 10844:2014. Available data from investigations by the vehicle and tyre industry and results from the STEER project show that the effect of ISO test track is significant. To estimate the noise variation on existing ISO test tracks, a small
Round Robin Test was conducted on 3 of them, as a part of the joint Polish-Norwegian project ELANORE. The modified CPX method was used for this purpose. Measurements were performed for 9 selected tyres of summer, winter and all-season type, with label noise values ranging from 66 to 74 dB.
Additionally, 2 standard reference tyres, P1 (SRTT) and H1 (Avon AV4), specified in the ISO 11819-3:2017 were tested. The obtained differences in noise levels for the tested tyres were up to 3.7 dB depending on test track. The ranking of tyres regarding measured noise levels didn't correspond
at all to the noise values given on tyre labels.
Characterizing noise barriers: SOPRANOISE final report and outcomes
Authors: Clairbois Jean-Pierre , Garai Massimo , Guidorzi Paolo , Conter Marco , Fuchs Andreas , Bartolomaeus Wolfram , Chudalla Michael , Strigari Fabio , Nicodeme Christophe
Published: February 2023

SOPRANOISE targets a three-step approach for assessing the in-situ intrinsic acoustic performance of road/railway noise barriers in regard to airborne sound insulation and sound reflection under direct sound field conditions. This approach goes from the in-situ inspections method (targeting
at the acoustic effect in the far-field) to the standardized measuring methods EN 1793-5 and 6, with "quick and safe" measuring methods in between. Papers about SOPRANOISE have already been presented in 2020 and 2021 as progress reports. The research ended in February 2022 and the
final outcomes are now presented. The main part of the pending work has been done within Work Package 4 (WP4). Herein, a new "quick and safe" method was designed and validated both in the lab and in situ. The new measuring equipment is portable, lightweight and uses a linear antenna;
the measurement itself is fully automated and the results show a very good correlation with full EN 1793-5/-6 results. WP4 results are particularly successful and, together with the in-situ inspection, those methods are ready to be submitted to the relevant CEN/TC226/WG6 working group to draft
a new framework on noise barriers assessment. All main reports are public available on the SOPRANOISE and CEDR webpages.
Acoustic source localization in ports with different beamforming algorithms
Authors: Fredianelli Luca , Bernardini Marco , Del Pizzo Lara Ginevra , Tonetti Francesca , Fidecaro Francesco , Licitra Gaetano
Published: February 2023

Acoustic cameras are used to investigate the origin of a noise and localize it on video for a couple of decades. This was made possible by applying beamforming techniques to the acoustic signals simultaneously acquired by a microphone array. The number of scientists working on improving
the efficiency and accuracy of this technique increased over the years, leading to the design and production of different shapes for the antenna and microphone array. Moreover, in the last years many different algorithms for beamforming techniques have been published to improve the original
"Delay and Sum" method. This field is evolving rapidly and, unfortunately, there is no clear view on the advantages of one method over another, both from a theoretical and a practical point of view. This work shows the different results obtained by different algorithms when applied
to the same input acoustic signals, i.e., they can localize the noise source in different points of the screen. The input signals were acquired with acoustic camera measurements to investigate port noise, a topic that has been neglected for too long and on which only few studies have been
carried out. The various sound sources acting on ships' pass-by and the predominant emitters in a multi-source environment have therefore been localized using the different algorithms.
Prediction of noise from mechanical ventilation systems in dwellings: case studies
Authors: Dijckmans Arne
Published: February 2023

Noise caused by mechanical ventilation systems in dwellings remains a common problem in practice. To help designers and installers, a simplified acoustic calculation tool has been developed which can be used without detailed acoustic knowledge. The tool is based on the prediction models
in EN 12354-5 and VDI 2081 and takes into account the airborne duct sound. The model has been validated by multiple case studies in dwellings. For each case study, the noise levels and airflow rates of the mechanical ventilation system have been measured in each room. Generally, the global
A-weighted noise level is predicted with an accuracy of ± 3 dB, on the condition that the airborne duct sound is dominant and sufficiently accurate acoustical input data are available for key components like fans, silencers and air openings. However, some measurement results cannot
be predicted by the simplified calculation framework, e.g. when turbulence in two closely placed fittings leads to additional flow noise. The uncertainty also increases when the fan sound is dominated by tonal components.
Speech enhancement for helicopter headsets with an integrated ANC-system for FPGA-platforms
Authors: Timmermann Johannes , Ernst Florian , Sachau Delf
Published: February 2023

During flights, helicopter pilots are exposed to high noise levels caused by rotor, engine and wind. To protect the health of passengers and crew, noise-dampening headsets are used. Modern active noise control (ANC) headset can further reduce the noise exposure for humans in helicopters.
Internal or external voice transmission in the helicopter must be adapted to the noisy environment and speech signals are therefore heavily amplified. To improve the quality of communication in helicopters speech and background noise in the transmitted audio signals should be separated. Subsequently
the noise components of the signal are eliminated. One established method for this type of speech enhancement is spectral subtraction. In this study, audio files recorded with an artificial head during a helicopter flight are used to evaluate a speech enhancement system with additional ANC
capabilities on a rapid prototyping platform. Since both spectral subtraction and the ANC algorithm are computationally intensive, an FPGA is used. The results show a significant enhancement in the quality of the speech signals, which thus lead to improved communication. Furthermore, the enhanced
audio signals can be used for voice recognition algorithms.
Accelerated sound propagation using an error-free Fourier method coupled with the spectral-element method
Authors: Borrel-Jensen Nikolas , Engsig-Karup Allan Peter , Hornikx Maarten , Jeong Cheol-Ho
Published: February 2023

Simulating acoustics using numerical methods efficiently and accurately has been an active research area for the last decades and has applications in computer games, VR/AR, and architectural design. However, their extensive computation time makes these methods challenging for large
scenes and broad frequency ranges. This work attempts to accelerate the simulations using rectangular decomposition, enabling error-free propagation in the bulk of the domain consisting of air. We exploit the analytical solution to the wave equation calculated using the Fast Fourier Transform
with near-optimal spatial and temporal discretizations satisfying the Nyquist criterium. Coupling with the spectral-element method near the boundaries results in a method capable of handling complex geometries with realistic boundaries, though with the caveat that additional errors and computational
overhead may result from the interface. This talk will investigate the accuracy and efficiency of the proposed domain decomposition method compared to a spectral-element method running in the entire domain.
The effect of main stage flow velocity on thermoacoustic instability of stratified swirl burner
Authors: Han Meng , Han Xiao , Wang Jianchen , Lin Yuzhen
Published: February 2023

In this paper, two group experiments were conducted to study the effect of the main stage flow velocity on thermoacoustic instability and flame macrostructure. The experiments were carried out under atmosphere condition, and namely the pilot stage flame mode and the stratified swirl
flame mode. The experimental results show that in the pilot stage flame mode, the thermoacoustic oscillation amplitude remains constant (around 1000 Pa) with the decrease of the main stage flow velocity. But when the velocity is zero (without main stage air), the thermoacoustic instability
disappeared. In the stratified swirl flame mode, the amplitude of thermoacoustic instability is the largest (around 300 Pa) when the main stage flow velocity is 6.2 m/s, and the amplitude is slightly smaller in other working conditions. The time-averaged flame shape under the two flame modes
is recorded and discussed. This paper highlights the effect of interactions between the pilot stage flame and main stage air or flame on thermoacoustic instability.
The eventful environment that characterises Indonesia's urban soundscape
Authors: Mediastika Christina E , Sudarsono Anugrah S , Utami Sentagi S , Fitri Isnen , Drastiani Rizka , Winandari MI Ririk , Rahman Akbar , Kusno Asniawaty , Mustika NW Meidayanti , Mberu Yuliana B , Yanti Ressy J , Rachman Zulfi A
Published: February 2023

Noise control is still one method to improve the urban acoustic environment in many countries, including Indonesia. The noise control tries to reduce the sound level in a particular space to increase comfort. In other words, the acoustic environment is designed to be comfortable and
uneventful. Previous studies have shown that public spaces in Indonesian cities have a unique sound than cities in developed countries. Here, further studies to investigate whether the soundscapes of these cities are also unique are reported. Soundscape surveys added with sound pressure level
(SPL) measurement and audio recording in 28 public places in ten major Indonesian cities indicate that a noise control approach to provide acoustic comfort and uneventful public spaces may not suit Indonesia. The analysis shows that, in general, the soundscape is perceived as an eventful environment,
which is compatible with the SPL and audio recording. Furthermore, the results were significant among the ten cities. This study shows that soundscape improvement should focus on developing an environment that is perceived as eventful and comfortable at the same time. Therefore, a different
strategy is needed to improve the acoustic environment in Indonesia.
Influence of several audio parameters in urban sound event classification
Authors: Domazetovska Simona , Gavriloski Viktor , Anachkova Maja
Published: February 2023

This paper presents a system for recognition and classification of sound events established through the development of processes for detection and parameterization of sound signals that are used for further classification by applying machine learning algorithms. The focus is on the
feature extraction process and the accuracy achieved when using different audio parameters. Five audio parameters were analyzed and tested on three machine learning algorithms order to investigate their influence in recognizing the class of the disturbing sound events in the urban areas, thus
yielding to a collection of 48 different combinations. The applied audio parameters: MFCC, Mel Spectrogram, Chromagram, Spectral Contrast and Tonal Centroid were chosen as they are widely used for urban noise classification, but their combination forming diverse feature vectors have not been
still analyzed. The accuracy results were different for each combination of the audio parameters, thus leading to choosing best set of parameters that reach the highest recognition accuracy. The used algorithms: Random Forest (RF), Naïve Bayes (NB) and Support Vector Machines (SVM) classifier
are chosen as they have shown very efficient classification in the field of urban noise recognition.
Experimental acoustic testing of alternative ventilation ducts
Authors: Zekic Suzana , Gomez-Agustina Luis , Aygun Haydar , Chaer Issa
Published: February 2023

Ducts of alternative materials to galvanised steel, are widely employed in residential buildings' mechanical ventilation systems in a bid to comply with the conservation of energy regulations in circumstances that prevent the use of natural ventilation. The noise transfer predictions
of systems with alternative ducts are still being based on data for galvanised steel due to the lack of the acoustic performance data of alternative ventilation ducts tested in controlled conditions. To close this knowledge gap, alternative ventilation ducts and associated 90º bend samples
were acoustically tested in controlled laboratory conditions utilising the substitution principle as outlined in BS EN ISO 7235 (2009) as well as applying a novel "zero substitution" approach. Static and dynamic tests were undertaken and sound attenuation (per meter) as a function
of frequency was obtained. Preliminary results revealed the different acoustic characteristics of alternative ventilation ducts when compared to published galvanised steel ducts. The "zero substitution" approach showed good agreement with results obtained from the standardised substitution
method when tested in straight duct sections. It is expected that the new acoustics knowledge on alternative ventilation ducts will influence the current design approaches and enhance confidence in noise transfer predictions resulting in cost and energy savings.
Challenges in delivering effective noise management at gas compressor stations
Authors: HANTSCHK Carl Christian , GEISLER Marco
Published: February 2023

The basic principles applied in gas compressor stations to manage noise and demonstrate compliance with statutory acoustic requirements are not different from those used with most other industrial activities. Well-known and proven standard procedures involve sound emission assessment,
acoustic modeling, model verification, development of a noise control concept and its optimisation until compliance can be demonstrated. However, noise control for some of the typical equipment in gas compression is extremely demanding in terms of both acoustic and operational/safety aspects
so that it requires special attention. Examples are the exhausts of the gas turbines driving the compressors and the extensive network of gas piping. Because of their high and strongly varying sound emissions the exhausts pose a significant challenge in designing effective silencers. In addition,
flow-generated self-noise in the silencers is a risk that needs to be avoided. For the piping sound attenuation by acoustic lagging is in conflict with corrosion and maintenance/accessibility problems and makes an optimised lagging concept an ambitious task. The present contribution illustrates
typical problems encountered and possibilities to deal with them. It is based on data and experiences with gas compressor stations with very stringent acoustic requirements.
Systematic review and meta-analyses of association between transportation noise and Ischaemic heart disease based on studies published between 1994 - 2022
Authors: Hamilton Sophie , Fenech Benjamin , Gong Xiangpu , Vienneau Danielle , Hansell Anna
Published: February 2023

There is a growing body of evidence that exposure to transportation noise can increase the risk for ischaemic heart disease (IHD). However, there are significant variations in the pooled exposure-response relationships (ERRs) derived by recent meta-analyses. These discrepancies lead
to uncertainties in health impact assessments and in public health policy decision-making. Updated analyses are needed to better understand this relationship. This paper presents an update to recent systematic reviews and meta-analyses investigating the effects of transportation noise exposure
on IHD mortality and morbidity. Specific aims are to understand if studies published since 2019 affect pooled ERRs and assess if evidence for aircraft and railway noise exposure has strengthened. We included studies from two meta-analyses and one literature review covering the years 1994-2020.
We then conducted an updated literature search in PubMed, Scopus, Web of Science and Medline for the period October 2020 and January 2022, following the same protocol as the WHO Environmental Noise Systemic Review Group. 30 studies were included from the previous reviews, and nine further
studies were identified via the updated literature search. The studies present risk estimates for IHD incidence (n=36), prevalence (n=5) mortality (n=26). The updated evidence and exposure response analysis is presented for Lden.
The effects of different types of noise on thermoacoustic systems using a Green's function approach
Authors: Arabi Sadaf , Heckl Maria
Published: February 2023

In this paper, we take advantage of using a Green's function approach as an analytical tool to study linear and nonlinear aspects of thermoacoustic systems. Green's function is defined as the impulse response of a system, it has a clear physical meaning in combustion systems, and it
provides a fast and flexible tool to predict thermoacoustic instabilities in both time and frequency domains. In this study, we consider a Rijke tube, which houses two sources: a heat source and an external noise source. The heat source is modelled by an amplitude-dependent nτ-law, the
noise source is assumed to emit two types of noise (pink noise or white noise). We use the Green's function approach to derive an integral equation for the acoustic field in the Rijke tube, and we also derive an algebraic equation for the thermoacoustic eigenfrequency. Both equations are validated.
The results that we found, show that the presence of noise (whether pink or white noise) results in "triggering" an instability and in accelerating the growth of the amplitude. These effects become more pronounced as the level of noise increases. The influence of pink noise is stronger
than that of white noise. We also studied how the hysteresis behavior (a nonlinear effect in dynamical systems) is affected by the noise, using the heat source position and heater power as bifurcation parameters. Our study reveals that the width of the bistable region decreases as the strength
of noise increases.