bluuebunny/crossref_metadata_2025 huggingface dataset:
Instrumentation Techniques for the Measurement of Gunfire
Authors: Nash Anthony
Published: February 2023

The peak sound pressure from near-field small arms gunfire is commonly used when assessing a shooter's hearing damage risk. Close to a shooter's ear, the peak sound pressure level from a rifle or pistol can be 155-to-160 decibels with a pulse rise time on the order of ten microseconds.
Standard dosimeters equipped with conventional measurement microphones significantly under-report the true peak levels from proximate gunfire; hence, the shooter's exposure is either unknown or underestimated. The U.S. Military has established exposure limits for small arms gunfire; however,
the specified properties of the measurement instrumentation are more prescriptive than performance-based. The implication is that the practitioner is responsible for pre-qualifying his or her own instrumentation. For near-field gunfire, the leading cause of measurement error occurs when the
wide-band signal from the acoustical transient is transduced by a relatively large-diameter measurement microphone having limited bandwidth. Secondary measurement errors include the finite bandwidth of the microphone signal amplifier and its slewing limit, the characteristics of the anti-aliasing
filter used, and the sampling rate of the digital recording device. The paper discusses these instrumentation constraints and recommends minimum performance requirements to help attain reproducible measurements of small arms gunfire.
Time delay estimation via average magnitude differences among multiple microphone signals
Authors: Zhu Zhen , He Hongsen , Chen Jingdong
Published: February 2023

Time delay estimation (TDE) plays a significant role in hands-free speech communication systems for localizing and tracking speakers. To boost the robustness of time delay estimators in room acoustic environments, a novel TDE approach is proposed in this paper. This method first exploits
the reciprocals of average magnitude difference functions of sound signals captured at a microphone array, instead of cross correlation coefficients, to construct the entries of the parameterized correlation coefficient matrix in the multichannel cross-correlation coefficient algorithm. A
multichannel average magnitude difference coefficient is then defined to establish the time delay estimator. Simulation results demonstrate that the proposed TDE strategy can yield better performance as compared to the multichannel cross-correlation coefficient method in noisy and reverberant
environment.
Development of Room Acoustic Prediction and Evaluation Tools for Designers
Authors: Seike Yukiko , Miura Daisaku , Ishizuka Takashi , Kitajima Kanaya , Kato Ayame , Miyajima Toru
Published: February 2023

We develop room acoustic prediction and evaluation tools for designers to be used in halls and conference areas where the design of acoustical performance is essential. The designers, with no specialized knowledge of acoustics, are able to examine the tools at an early stage of the
project. The interface tool consists of the 3D CAD software-Rhinoceros, and its plug-in tool-Grasshopper. The designers first build a room model on Rhinoceros and locate the sound source and the receiver points in the model. They then set the calculation conditions via Grasshopper, such as
room use and type of interior finishes. Next, room sound propagation is calculated using the ray tracing method in the external python programs. Then, acoustic indices, such as the average sound absorption coefficient and clarity, are predicted. These indices are automatically evaluated according
to the room use, and the evaluated results are visualized in the room model on Rhinoceros. This paper outlines these tools and exhibits the agreement of predicted and measured indices in a small hall. These tools are applied to a lecture room with complicated ceiling ribs, and an office with
a stairwell, which are difficult to examine by the conventional reverberation formula.
Study on Power-level Measuring Method of Structure-Borne Noise of Viaduct Road
Authors: Mori Tatsuaki , Ikeya Kimikazu , Itiki Tomoyuki , Fukushima Akinori
Published: February 2023

Noise is generated when vehicles running on the viaduct road cause the structure to vibrate. The authors studied a measuring method for the power levels of structure-borne noise of viaducts, generated when tyres of running vehicles excite the road surface. This paper reports on the
findings of the study on the effects of diffracted noise and measuring positions on the measured power levels. On the effect of diffracted noise, as a result comparing the structure-born noise measured at a point on the boundary of the road bridge site with a value gained by subtracting the
diffracted vehicle noise from the measured noise, it was confirmed that the effect of diffracted noise is sufficiently low. As for the influence of measuring positions, when comparing values measured at a position located 1.2 m above ground with those at 0 m, a difference of about 3 dB was
found. Considering the fact direct waves and ground reflected waves synthesize, it was confirmed that the difference is valid. As this study shows, influences of diffracted waves and measuring positions are small, and based on these results, the practical measuring method is proposed.
Three-dimensional nonlinear thermoacoustic instability analysis based on Green's function approach
Authors: Zhou Weipeng
Published: February 2023

In this work, nonlinear thermoacoustic instability analysis is made in a hard-walled box to investigate the limit cycle of thermoacoustic oscillation and the interplay of two modes. We model the flame as an acoustically compact source described by a generic Flame Describing Function,
i.e. an amplitude-dependent Flame Transfer Function. The acoustic field in the hard-wall box could be described by an integral equation using a Green's function tailored to a three-dimensional (3-D) rectangular box with hard-wall boundary conditions. The integral equation is solved by two
methods. Firstly, an iteration method, stepping forward in time, is used to give the time history of the acoustic velocity. The other method is done in the frequency domain to determine the thermoacoustic eigenfrequency and growth rate of thermoacoustic modes. We could observe the phenomenon
of modes "jump" after two different time windows of the time history operated with the Fourier transformation. This result reveals that there are two modes in the system, the interference between modes will occur. In the early stage, the two modes work together. After reaching the
limit cycle oscillation, the role of one mode is dominant and the other mode basically disappears.
Optimisation of railway noise barrier design using finite element and boundary element modelling methods
Authors: Bustos Cesar , Jurdic Vincent
Published: February 2023

The prediction of environmental noise barrier insertion loss (IL) is commonly undertaken from widely available empirical methods derived from measurements and geometrical acoustic approximations. The accuracy of these methods is limited when analysing non-standard design parameters,
such as geometry; characteristics and location of sound absorbing materials; or diffraction effects close to the barrier. This article presents a new methodology to optimise the design of a railway noise barrier using a simplified numerical method. The numerical method is based on a two-dimensional
hybrid finite element and boundary element analysis. The numerical method has been calibrated and tested against measurements of high speed trains. The model assumes an infinitely long train with pre-defined sound sources (e.g. rolling source, body aerodynamic, etc.). The numerical model quantifies
the effect of various parameters upon the barrier IL including material properties; area and location of sound absorbing materials; diffraction over the barrier top; and analysis of energy build-up between train and barrier. These parameters are not easily quantifiable using standard methods
and hence the innovation aspect of the methodology. The outcome of this study can be used to optimise and improve confidence in the detailed design of complex noise barriers.
A large-scale study of the social response to construction noise in Hong Kong
Authors: Chan Silver , Lam K.C. , Wong C.L. , Kwan Richard , Ho Wilson , Cheng Morgan , Yiu Max
Published: February 2023

Construction noise is an issue in many large cities with potential annoyance and disturbance effects. With an aim to providing necessary data for formulating noise control strategies, a large-scale social survey was commissioned in Hong Kong and undertaken by a team of acoustic experts
in 2018-2020. Based on the interview of around 5,000 randomly selected households following the ISO standard on 11-point numeric scale (ISO/TS 15666, 2003), this was one of the few large-scale studies carried out in a dense and compact city. This paper describes the rationale and approach
of the study, the sampling and questionnaire design. Some of the key study findings are presented, highlighting in particular the prevalence and nature of construction and domestic renovation noise; annoyance and sleeping response of the respondents that would be useful for developing construction
noise management strategies in Hong Kong. The findings are also compared with the data collected in an earlier similar study undertaken 10 years ago to analyze the trend and changes in people's perception on construction noise impacts.
Modelling the uncertainties of wind farm noise predictions
Authors: Kayser Bill , Ecotière David , Gauvreau Benoit
Published: February 2023

Representative predictions of wind turbine noise require to accurately model the main mechanisms and characteristics of acoustic emission (i.e., extended sound source with aeroacoustic noise generation) and acoustic propagation in outdoor environment (i.e., ground effects and atmospheric
properties). As these phenomena fluctuate over time and space, it leads to great uncertainty on Sound Pressure Level (SPL) estimated at local resident bulidings/facades. Such uncertainty is not yet properly quantified by engineering noise prediction models. Thus, this paper presents a modeling
tool developed in the framework of the French project PIBE, which aims at quantifying the SPL uncertainty involved in wind farm noise predictions. Ultimately, this modeling tool will be freely available online and will help to better understand the risk of noise pollution at each stage of
a wind farm's life, in order to guarantee compliance with the regulatory requirements concerning the exposure of local populations.
Analysis of Combustion Noise Sources Using Doak's Momentum Potential Theory
Authors: D'Aniello Raffaele , Knobloch Karsten , Kissner Carolin
Published: February 2023

Noise emissions of modern lean combustors are related to different sources. Direct combustion noise is generated by heat release fluctuations, while indirect noise sources include the acceleration of entropy and vorticity inhomogeneities through the nozzle-guide-vane or at the combustor
exit. The latter noise source is characterized by the coupling of fluctuations convected in non-uniform mean flow, which can e.g. cause vortical or entropic fluctuations to be partly transferred into acoustics. Due to the complexity of the sources, a clear and quantitative separation of the
different phenomena in terms of primitive variables presents a significant challenge. This study therefore proposes an alternative framework for the description of combustion noise based on Doak's Momentum Potential Theory (MPT). The MPT defines a Generalized Acoustic Field (GAF) and describes
the sound production in terms of mean energy fluxes carried by the respective acoustic, thermal and turbulent fluctuating momentum components. To confirm the ability to identify the different combustion noise sources, the method was applied to Large-Eddy Simulation data of a non-reacting swirl-combustor
simulator. Finally, the coherent character and spectral behavior of the GAF were investigated using a Spectral Proper Orthogonal Decomposition (SPOD) analysis and correlated to the source distributions.
Sound environments and citizen action: what place for a participatory sciences tool? The case of the city of Rezé using NoiseCapture
Authors: Can Arnaud , Audubert Philippe , Aumond Pierre , Guiu Claire , Lorino Tristan , Rossa Emilie
Published: February 2023

Local authorities are increasingly interested in implementing participatory processes, associating inhabitants in decision-making. The Sonorezé project, involving researchers from the Gustave Eiffel University and the City of Rezé, evaluates the interest of a smartphone
application for participatory noise measurement, namely Noisecapture, as a vehicle for this citizen participation in the noise context. The project includes the recruitment of participants, the creation of participatory noise maps integrating different indicators, and the constitution of discussion
groups that aim to elaborate concerted proposals regarding noise mitigation. In parallel, one will evaluate how access to this tool modifies the perception that inhabitants have of their soundscape, and facilitates their empowerment and the valorization of their inhabitant knowledge. This
communication will present the whole workflow, highlighting how this framework helps to raise awareness of urban noise environments among inhabitants. Then, one will present in detail the dynamics of the recruitment, which amounts to more than 100 participants that performed almost 1000 measurements,
at the stage of the first 4 months. The diversity of the participants' profiles, the temporal and spatial heterogeneity in the measurements, are however possibly an obstacle to the production of representative noise maps, which will be discussed in the communication.
Efficacy evaluation of low-emission asphalts in port areas using the CPX and SPB method
Authors: Licitra Gaetano , Fredianelli Luca , Del Pizzo Lara Ginevra , Moro Antonino , Bianco Francesco , Fidecaro Francesco
Published: February 2023

The INTERREG IT-FR Maritime financed various projects for filling the gap in knowledge regarding port noise, recognized as environmental issue in the Tyrrhenian area. Passenger road traffic and heavy vehicle traffic related to port activities are among the main sources of disturbance,
together with ship noise and dockside operations. Among several projects, REPORT developed simulation models and guidelines for noise evaluation and control strategies, then applied for mapping noise in various ports of the projects. MON ACUMEN installed continuous noise monitoring units.
The main objective of RUMBLE was to reduce port noise and, among the noise mitigation interventions that were prescribed by the project and carried out during the three years, low-emission asphalts were laid in the Italian ports of Portoferraio (LI) and Cagliari, and in the French ports of
Bastia and Ile Rousse. The present work evaluates the effectiveness of these acoustic interventions by comparing the results of specific measurement campaigns carried out before and after the new laying. The measurements were carried out using both the CPX methodology, which evaluates the
noise emission due to the interaction of the tyre with the pavement, and the CPB methodology, which is based on the acquisition of the noise levels produced on the roadside by the passage of the test vehicle on the investigated pavement. Since the two tests were performed simultaneously with
the same vehicle, these measurements provide a good estimate of the efficacy of the low-noise pavements in a port environment.
Auralisation of combined mitigation measures in railway pass-by noise
Authors: Pieren Reto , Georgiou Fotis , Squicciarini Giacomo , Thompson David J.
Published: February 2023

To reduce noise exposure along railway lines various combinations of noise mitigation measures can be considered. However, predicting and assessing their effects is non-trivial and the potential need for multiple measures is difficult to communicate to stakeholders. Auralisation is
a promising tool that can help to support communication and decision-making, and enable psychoacoustic evaluations. This paper presents developments of a physics-based auralisation model for train pass-bys that allows various mitigation measures to be included. The work is conducted within
the European research project SILVARSTAR. The proposed model includes contribution from rolling noise, impact noise, traction, auxiliary systems, and aerodynamic noise. It is physically based and allows a direct assessment of pass-by parameters such as speed, roughness, wheel flats and track
design. Based on the TWINS model, five structural transfer paths for rolling noise are considered to integrate mitigation measures such as wheel and rail dampers. Shielding by noise barriers is simulated with analytical models. Reflection at different ground types is considered and can account
for track embankments. The results can be coupled to an immersive Virtual Reality environment, by first panning the synthesised sounds to a small virtual speaker array and subsequently dynamic binaural rendering for headphones.
Parametric design of a modular acoustic panel for sound recording space versatility
Authors: Tagios Stavros , Gomez - Agustina Luis
Published: February 2023

Increasingly sound recording studios are demanded to host projects of different acoustic needs. However, their sonic character, product of their contents and bulky conventional treatment solutions, usually remains unchanged. This paper reports a modular panel's early-stage design, aimed
at providing flexibility to a group of representative recording rooms. The versatility refers to acoustical (absorption and diffusion), practical (volume and weight), and aesthetic aspects. The geometry and materials of the panel were derived parametrically through computer modelling software,
by implementing interdependent and adaptable elements to one unit. Existing recording spaces were recreated into computational acoustic models and tested in two states. Simulations of the rooms' acoustical behaviour were run in turn, first with the original treatment, then with the panel replacing
the treatment. The design goal was to have minimal differences in Reverberation Time, Early Decay Time, Clarity, Room Frequency Response for every room's two states. Results showed the panel performing better in rooms with larger volume. Overall, the panel matched the original acoustic response
and character of the rooms, while providing versatility when compared to traditional acoustic treatment solutions. The development of such a product would allow future studio users fine tune the room's performance according to their needs.
Improved acoustics for semi-enclosed spaces in the proximity of residential buildings
Authors: Taghipour Armin , Gisladottir Arnthrudur , Aletta Francesco , Bürgin Matthias , Rezaei Mohadeseh , Sturm Ulrike
Published: February 2023

Continuous urban densification exacerbates acoustic challenges for residents of housing complexes. They are confronted with higher noise immission from railway, road traffic, construction, as well as louder neighborhood acoustic environments. Thereby, not only noise immission indoors
is associated with stress, annoyance, and sleep disturbance, but also the immediate outdoor living environment (e.g., courtyards, private gardens, and playgrounds, etc.) can be acoustically unpleasant and annoying. This non-exhaustive narrative review paper elaborates on the role of a number
of design parameters on improving the quality of the outdoor soundscape of housing complexes: architectural and morphological design, facade material characteristics, balconies, greenery, ground, background sounds, and several factors concerning quality of sounds (e.g., multisensory perception,
holistic design, the relevance of space, context, social factors, co-creation, etc.). It mainly covers literature including both acoustical (e.g., sound pressure level and room acoustical parameters) and human/perceptual (e.g., comfort and annoyance) factors. A series of recommendations are
presented here as to how the semi-enclosed outdoor spaces in the proximity of residential complexes can be acoustically improved.
Construction details affecting flanking transmission in cross laminated timber structures for multi-story housing
Authors: Neusser Maximilian , Bednar Thomas
Published: February 2023

The desire of the building developers to leave the surfaces of cross laminated timber constructions in multi-story housings visible for the building user, leads to acoustic problems with the flanking sound transmission that cannot be controlled by means of wall linings. As a result,
controlling flanking sound transmission by measures directly in the joint is getting increasingly important. The main parameter for describing the vibrational power transmission over a junction between structural elements is the vibration reduction index Kij. For this quantity, some planning
values are spread over numerous publications. None of the currently available data sources represents a holistic view on the building acoustic performance of the on the market available products for elastic interlayers and fasteners which are used in a wall-ceiling junction. The following
paper shows results of measurements of vibration reduction indexes of different configurations of a wall-ceiling joint in a test facility. Different elastic interlayers and fasteners were investigated. The vibration reduction indexes spread from 16db to 26dB as a function of the joint configuration
and the load applied on the joint. The measurement results obtained are discussed and the essential parameters for influencing the flanking sound transmission are worked out and quantified.
Causal-based acoustic optimization of micro-perforated structures with rigid backing
Authors: Bravo Teresa , Maury Cédric
Published: February 2023

The acoustical design of compact micro-perforated absorbers (MPA) that exhibit high performance over a broad bandwidth is a difficult challenge, often faced in building, ventilation and transportation industries. A causal-based optimization criterion of the MPA constitutive parameters
is considered as an alternative to the maximization of the frequency-weighted overall absorption. It maximizes the directional gradient norm of the total intensity reflection coefficient (in logarithmic scale) integrated over all positive wavelengths. The causal and standard optimization strategies
are assessed for single- and double-layer MPAs as well as for MPA arrays, the former (resp. the latter) designs being supported by Kundt tube measurements (resp. finite element simulations). The causal criterion ensures perfect absorption and the broadest possible bandwidth at one or several
Helmholtz resonances of the MPA, with efficient grouping and merging of these resonances for the optimized MPA array. The resulting performance are comparable to direct maximization of the total inverse-frequency weighted absorption.
Influence of contact parameters on the radiated noise from an automotive drum brake
Authors: Ramesh Ananthapadmanabhan , Rangamani Aditya , Sundar Sriram
Published: February 2023

Drum brakes are the major source of noise and vibrations in the automobile as the drum acts as a significant source of the noise. High-frequency noises are generated at the interfacial contact between the brake shoe and brake drum. Hence, the variation in the contact parameters (friction,
contact stiffness, and contact damping) will significantly affect the vibro-acoustic noise emanating from the drum brake. The current work quantifies the variation in vibro-acoustic noise due to an asymmetry in the contact of leading and trailing shoes with the drum. The overall sound pressure
level is estimated numerically using a finite element model of the drum brake. Multiple spring-like components in parallel between the brake shoe and the drum imitate the contact in real drum brakes. The numerical model predicts the noise generated by a symmetric system (without any asymmetry
defects) and a system with controlled asymmetric defects introduced into the model. The results show that the overall sound pressure level is a strong function of the contact parameters. The current research is envisioned to better the selection of contact parameters and hence the drum and
shoe properties.
Acoustic behaviour of CLT structures: influence of decoupling bearing stripes, floor assembly and connectors under storey-like loads
Authors: Kraler Anton , Brugnara Paola
Published: February 2023

Timber buildings do not have a high acoustic performance regarding vibration transmission through the structure. Sophisticated acoustic design methods are usually not applied and noise control design for wooden buildings is often merely based on the experience of engineers. To find
out the peculiarity of timber transmission, an acoustic lab test with CLT was set up. Several measurement configurations were built and airborne sound measurements according to EN ISO 16283-1 and impact sound measurements according to EN ISO 16283-2 were carried out. The test results were
set in relation to reference measurements on the bare CLT slab and on a floor assembly, with and without decoupling bearing stripes and with and without connectors. In addition to the standard sound measurements, the sound transmissions through the ceiling element and through the flank components
(walls) were also measured with accelerometers. The results showed in an experimental evaluation method a reduction in sound transmission and standard impact sound level. All tests were carried out with the same load of 17 kN/m on the decoupling bearing stripes and the ceiling element. The
load was applied by means of threaded rods and secured by strain gauges. The influence of decoupling bearings stripes, types of fastening systems and floor structures on sound transmission through the flanking components on a real scale mock-up could therefore be investigated.
Physics-aware learning of nonlinear limit cycles and adjoint limit cycles
Authors: Ozan Defne Ege , Magri Luca
Published: February 2023

Thermoacoustic oscillations occur when the heat released by a flame is sufficiently in phase with the acoustic pressure. Under this condition, the linear instability can saturate to a nonlinear self-excited oscillation with a large amplitude. A typical nonlinear regime is a limit cycle,
which is characterised by a periodic orbit in the thermoacoustic dynamics. In this paper, we develop a physics-aware data-driven method to predict periodic solutions using forward neural networks. The physics is constrained in two ways. First, the training is informed by a physical residual,
which penalises solutions that violate the conservation of mass, momentum, and energy. Second, periodicity is imposed by introducing periodic activation functions in the neural network. We test the algorithm on a nonlinear time-delayed model of a Rijke tube. Adjoint methods offer a cheap and
easy way to calculate the gradients with respect to design parameters, hence we extend our study to learning the adjoint variables of the Rijke system, which also settle onto periodic oscillations. We find that (i) periodic solutions of thermoacoustic systems can be accurately learned with
this method, (ii) for periodic data, periodic activations outperform conventional activations in terms of prediction capability beyond the training range, and (iii) under the physical constraints, fewer data is sufficient to achieve a good performance. This work opens up possibilities for
the prediction of nonlinear thermoacoustics by combining physical knowledge and data.
Annoyance of helicopter-like sounds in urban background noise
Authors: Schlittenlacher Josef , Wales Karine
Published: February 2023

Scenarios of urban air mobility see electric vertical take-off and landing aircraft (eVTOLs) operating within cities. Rotorcraft sounds are typically characterised by short bursts of noise, although eVTOLs offer more opportunities for a quieter sound design. We asked participants to
compare the annoyance of a reference sequence of bursts of noise with a burst duration of 20 ms with that of a test sequence for which the burst duration was 1 or 5 ms. There were 20 bursts/s. A two-interval, two-alternative forced-choice task and a 1-up/1-down procedure was used. Both sequences
were played in background noise that had either the same root-mean-square (RMS) level as the sequence of bursts or 10 dB less. The results were similar to those for loudness: On average, sequences with 1-ms bursts needed 6-7 dB less RMS level to sound equally annoying as the 20-ms bursts,
and sequences with 5-ms bursts needed 3 dB less. This suggests that psychoacoustic annoyance is mainly explained by loudness and that the RMS level is an insufficient descriptor. Compared between the two background noise levels, the level difference for equal annoyance between short and 20-ms
bursts was 1.5 dB larger in the louder background, which was statistically significant.
Self-Determined Hearing Through Artificial Intelligence (AI)
Authors: Sylopp Peggy
Published: February 2023

Due to the wide spread of hearing disorders in the industrialized countries, (approx. 14 million cases in Germany) this is one of the most common diseases. 75% of those affected don't use hearing aids, accepting consequences such as unemployment, depression and dementia, which results
in high economic damage. Studies have proven that individualized sound adjustment can result in greater satisfaction and participation. In the rapidly growing hearable market (hearable are hearing devices like head phones, head sets and hearing aids) sound personalization is an emerging trend.
More and more hearables feature user-adjustable sound. Latest, high-priced developments in the field of hearing aids integrate AI based on self-adjustment of sounds. In this talk I introduce new approaches to integrating AI in hearables for more self-determined hearing. I want to discuss the
opportunities of these approaches and limitations that still exist as well as the challenges for future developments.
From the costs of noise to the value of soundscape?
Authors: Jiang Like , Bristow Abigail , Kang Jian , Aletta Francesco , Thomas Rhian , Notley Hilary , Thomas Adam
Published: February 2023

The past two decades have seen an ongoing paradigm shift from noise control to soundscaping, and soundscape approaches have been widely applied in traditionally noise management projects. However, cost-benefit analysis (CBA), which is widely used for economic appraisals of projects
that would impact on the sound environment, is still noise-based and residential-location-focused. As a result, benefits of wanted sounds are omitted, and only very limited receiver types and contexts are covered. While there is a wealth of literature on valuing the costs of noise and the
benefits of noise reduction little research has been done on soundscape valuation, and consequently there is little evidence on the monetary value of soundscape, which is essential for developing soundscape-based CBA. Starting from the costs of noise this paper will discuss the motivation
of soundscape valuation, methodology for primary soundscape valuation research, and the use of soundscape values, to contribute to the development of holistic soundscape CBA.
A study on normal incident sound absorption characteristics of Japanese traditional cedar board, yakisugi
Authors: Sugahara Akiko , Okamura Kentaro , Hiraguri Yasuhiro , Yasui Noboru , Kaku Chihiro
Published: February 2023

Yakisugi is made by charring the surface of a cedar board to form a thin carbonized layer, which is said to improve durability, weatherability and fire resistance. It is a traditional Japanese exterior material that has become popular overseas due to its performance and visual texture.
Recently, it has been attracting attention for its use as an interior material, but its basic performance is still unknown. In this study, we focus on the sound absorption characteristics of yakisugi as one of the investigations to understand its performance as an interior material. The carbonized
layer of yakisugi is expected to have sound absorbing performance because of its porous nature. As a basic investigation, the sound absorption characteristics at normal incidence are measured using an impedance tube and compared with the carbonized layer conditions. It is found that yakisugi
has sound absorption performance in the high frequency range. Moreover, the characteristics are depending on the thickness and surface properties of the carbonized layer.
Study on sound source localization inside a structure using a domain transfer model for real-world adaption of a trained model
Authors: Kita Shunsuke , Kajikawa Yoshinobu
Published: February 2023

Sound source localization (SSL) is important to reduce noise of products such as machinery and electrical appliances. Currently, SSL methods have been proposed that use the correlation of time-frequency signals of sound waves observed by multiple microphones. However, the application
of these SSL methods are limited to the case where the acoustic signals can be directly observed. In the case of estimating the location of a sound source inside a structure from outside the structure, these methods are not applicable because the acoustic signal is observed as indirect sound.
An SSL method using deep neural network (DNN) and computer-aided engineering (CAE) was proposed to estimate sound sources inside structures. This method successfully estimates the location of sound sources inside a structure from signals observed by accelerometers installed on the outer surface
of the structure in both CAE and real domains. Nevertheless, the proposed method still has the challenge of adapting DNNs trained in CAE domain to real domain. In this research, deep convolution auto-encoder (DCAE) was used as a domain transformation model built from CAE and actual experimental
data. DCAE contributed to the improvement of the SSL performance of the trained DNN over the baseline.
Estimation of insertion loss for noise barrier with multichannel sound reproduction technology
Authors: Hoshika Satoshi , Doi Tetsuya , Hiroe Masaaki , Iwami Takahiro
Published: February 2023

A method based on the wave field synthesis is proposed to estimate the insertion loss of a noise barrier under the complex diffracted sound field due to the characteristics of the noise source and the transmitted sound through the barrier. This method is equivalent to evaluating the
acoustical performance of the noise barrier in a reproduced sound field. There are two advantages of the proposed method. First, by storing the radiated sound of various noise sources as a database in advance, the insertion loss for them can be obtained. Second, the impulse responses from
multipoint can be measured by changing one loudspeaker position sequentially, so it does not necessarily require many loudspeakers. In order to validate this method, numerical simulation was performed for a diffracted sound field consisting of a point source and a rigid barrier. Moreover,
the insertion loss of simple noise barriers for one loudspeaker was estimated under the primary and synthesized sound field conditions experimentally. As a practical example, the insertion loss of the same noise barriers for a moving automobile was also estimated. The results show that the
estimation error is within a few decibels in the frequency band where spatial aliasing does not occur.
An exponentially convergent adaptive robust based space manipulator noise control method
Authors: Liu Jinglong , Li Ning , Ma Xiaolong , Li Feng
Published: February 2023

Because most of the traditional nonlinear control methods are model-based control methods, it will dramatically increase the parameter identification burden of multi-rigid-body system dynamic model. Meanwhile, Unmodeled dynamics, parameter drift, model uncertainty, complex motor hysteresis
characteristics, etc are unfortunately in the practical systems, which makes it very hard to accurately build the noise model and identify the model parameters. Among them, the accurate values of the viscous friction coefficient, elastic friction coefficient, the distance between the centroid
and the rotation center of the connecting rod, the inertial moment and products of each joint, these exact values can hardly be obtained. In this paper, direct adaptive control and the robust model reference adaptive control based on Lyapunov direct method are adopted, which can make the noise
error close to zero under the condition of parameter uncertainty and unknown nonlinear friction characteristics.
Combination of Acoustic Black Holes with point masses
Authors: Hoffmann Steffen , Rothe Sebastian , Langer Sabine Christine
Published: February 2023

Passive acoustic measures are suitable for the targeted improvement of the vibration behaviour of technical products. In this context, Acoustic Black Holes (ABH) as innovative measures have shown great effect for an efficient damping of vibrations and a simultaneous mass reduction.
The vibration reducing effect, however, is primarily apparent in the higher frequency range. The thickness reduction results in a mass reduction of the system, which could worsen the vibroacoustic behaviour in the lower frequency range. The idea of the approach here is to use the saved material
in form of point masses to counteract this disadvantage at low frequencies by a targeted placement or direct consideration in the manufacturing process. The result is a mass-neutral acoustic design measure. In order to investigate the effectiveness of the ABH point mass combination, finite
element models of generic beam and plate structures with ABH are used in this paper. In addition, the influence of point masses in terms of their position and number on the vibroacoustic behaviour is simulated. One focus is the assessment of the advantage by combining ABH with point masses.
To validate the results, experimental investigations are carried out and compared with the numerical results.
Non-linear behavior of the transfer impedance of a Micro-Slit-Plate: effect of slit length in presence of a bias flow
Authors: Aulitto Alessia , Hirschberg Avraham , Lopez Arteaga Ines
Published: February 2023

The influence of the slit length and interactions between slits in a micro-slit plate (MSP) are investigated in the high amplitude regime. MSPs are plates with arrays of slit-shaped perforations, with width of the order of the acoustic viscous boundary layer thickness. The geometry
discussed in this work is typical for fabrication by cutting and bending the plate, without removing material. Micro-slit plates designed with optimal acoustic properties in the linear regime will not be optimal when non-linear effects become significant resulting in vortex shedding. Impedance
tube measurements of the transfer impedance on accurately manufactured micro-slit plates are compared to prediction by 2D incompressible Navier-Stokes model and to a quasi-steady theory. At moderately high amplitudes, the vortices remain close to the edges of the slit. The impedance of the
plate is predicted within 20% by the model of a single isolated slit. At higher amplitudes, the vortices are traveling far away from the slit and a complex behavior. In this region, three-dimensional effects become important. For very high amplitudes, the vortices shed at neighboring slits
start to interact, which affects the impedance.
Scaling of the simulated pass-by measurement based on the vehicle's acoustic centre
Authors: Weber Yannik , Albers Albert
Published: February 2023

Preliminary work by the IPEK - Institute of Product Engineering at KIT has shown that the simulated pass-by measurement for exterior noise homologation of vehicles has relevant optimization potential: the measurement can be carried out in smaller halls and with a smaller measurement
setup than required by the standard and thus with less building construction cost and measurement effort. A prerequisite for this, however, is the scaling of the entire setup. For the scaling to work correctly, the sound sources of the vehicle must be combined to a single point sound source
- the acoustic centre. Therefore, in a preliminary work, the IPEK developed a method, with the help of which the dominant sound sources of a vehicle can be localized and combined to an acoustic centre. In this work, the method is applied exemplarily on two test vehicles and their acoustic
centres are determined. Afterwards, the measurement setups for both vehicles are scaled based on the acoustic centres, Finally, the simulated pass-by measurement with the scaled measurement setup is performed on an acoustic roller test bench and the scaled sound pressure levels are determined.
To verify the overall method, the results of the scaled pass-by measurements are compared with the unscaled one and with measurements on the test track.
Acoustic measures of biodiversity and human disturbance - a study in the UK Yorkshire Dales National Park
Authors: Watts Greg
Published: February 2023

The Ingleborough Soundscape Project's study involved long-term monitoring of sonic environment of an ancient woodland and newly rewilded moorland site in order to contrast biodiversity and human disturbance. Both sites are located in the Ribble Valley located 6 km north of the village
of Horton in Ribblesdale. They lie in the NW area of the Yorkshire Dales national park in the UK. The sites are affected by both road and rail noise and by overflights. The ancient woodland (Colt Park Wood (CPW) lies 380m from the nearest road and South House Moor (SHM) is located over three
times that distance (1220m). The primary aim was to propose a simple, low-cost acoustical metric by which non-experts can measure the success of contrasting wildness interventions. This metric, which uses raw acoustic and ground-truthed data obtained from CPW and SHM, is an updated version
of 'Acoustically Enhanced Ecological Richness' (AEER), as initially proposed by Agius. Additionally, human impact was gauged by predicting noise exposure and converting to tranquillity levels using Tranquillity Rating Prediction Tool (TRAPT) and plotting contours across the study sites.
Application of wavy geometries for the reduction of trailing edge instability noise
Authors: Smith Tom , Ventikos Yiannis
Published: February 2023

Trailing edge instability noise can occur in a wide range of applications, including wind turbines and small aerial vehicles. It can be characterised by a high amplitude tonal or narrowband sound resulting from instability waves in the boundary layer scattering as they are convected
over the trailing edge. In this study, a hybrid aero-acoustic model is used to demonstrate how wavy geometries can be used to successfully reduce trailing edge instability noise. The hybrid model uses incompressible large eddy simulations to compute acoustic source terms, which are then mapped
onto a larger domain using radial basis functions. The acoustic perturbation equations are then solved on this larger domain to obtain the 3-dimensional acoustic field. The study uses a modified NACA0012 wing, where the surface contains spanwise waves of different wavelengths. The results
show that there is an optimal wavelength that produces the greatest noise reduction for a given flow speed and Reynolds number, and that this relates to wavelengths of the dominant structures within the boundary layer. This shows that by understanding the spectral character of the boundary
layer, one can design optimal geometries for reducing this important source of fluid-induced noise.
Evaluation of flyover auralisations of today's and future long-range aircraft concepts
Authors: Schäffer Beat , Bertsch Lothar , Le Griffon Ingrid , Heusser Axel , Lavandier Catherine , Pieren Reto
Published: February 2023

The European research project ARTEM (Aircraft noise Reduction Technologies and related Environmental iMpact) develops innovative aircraft noise reduction technologies such as advanced engine fan lining, metamaterials and low-noise high-lift systems applied to a vehicle with enhanced
shielding of the engine noise, namely, a blended wing body. Using aircraft flyover auralisation in laboratory listening experiments, such future technologies can be evaluated with respect to human sound perception. To assess the reliability of such perception-based evaluations, the simulation
chain should be validated with existing aircraft flyovers. This contribution presents a systematic and rigorous hierarchical validation of auralisations of current jet aircraft using field recordings. Uncertainty in the source modelling is considered by using two different prediction tools
for partial sound sources. In addition to comparing computed noise indicators, a psychoacoustic validation is done in laboratory listening experiments with a 3D loudspeaker array. The validation comprises three levels: (i) direct comparison of auralisations with recordings to study the identifiability
of auralisations, (ii) ranking of auralisations and recordings regarding plausibility, and (iii) subjective annoyance ratings to test whether auralisations and recordings differ with respect to noise effects. Further, first results on the comparison of a future concept with a current aircraft
are presented.
Ideas for improving diversity and inclusion in acoustics
Authors: Lamacraft Angela , Witterick Susan
Published: February 2023

Diversity within the acoustic profession in the UK is gradually widening in general, but there is still a significant need for improvement in terms of inclusion, diversity and equality. In order to address this need the UK Institute of Acoustics (IOA) has recently established a working
group to examine the current situation within the Institute and within the wider profession in the UK. This paper will provide a summary of the current membership demographics of the IOA to provide a benchmark for improvement. Examples of successful initiatives from other national acoustical
societies will be provided and ideas for improving the numbers and experience of underrepresented people in the IOA will be discussed.
Usage of the 2.5D Boundary Element Method for the Detection of Moving Noise Sources
Authors: Waubke Holger
Published: February 2023

The boundary element method in 2.5D allows for the usage of moving sources by a modification in the wave number frequency domain. The 2.5D boundary element method uses a Fourier transformation about time and the axis of movement of the object. The boundary element method is applied
to the cross section. To use the method it has to be assumed that the cross section is constant along the direction of movement. An advantage of the method is that reflections in the sound path caused by the ground are taken into account. The inverse form of the method is used for the detection
of noise sources on railway trains. Recordings made with a 64-channel microphone array at the high-speed railway line near Vienna will be investigated by this method. A big disadvantage is the fact that only eight positions along the track and eight positions in the cross section were measured.
This leads to the fact that the wave number can only be estimated in as rough manner and that the IBEM has much more unknowns than measured position exist. The second point needs for a regularization. An advantage of the method is that the vibration at the surface is determined.