bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of geometrical defects on the acoustical and transport properties of periodic porous absorbers manufactured using stereolithography
Authors: Lomte Amulya , Sharma Bhisham
Published: June 2023

Additive manufacturing allows the fabrication of acoustical materials with previously unrealizable micro- and macrostructural complexities. However, the still nascent understanding of various geometrical defects occurring during the additive process remains a barrier to accurately predicting
the acoustical behavior of such complex absorbers. In this study, we present the results from our efforts on numerically modeling the absorption behavior of periodic porous absorbers fabricated using the stereolithography (SLA) technique using the hybrid micro-macro multiphysics approach.
Specifically, we focus on understanding the role played by the expansion or shrinkage of the solid ligaments during the SLA process on the transport parameters of the final printed samples. First, the periodic absorbers are modeled using COMSOL multiphysics, where the transport properties
are derived using the Johnson-Champoux-Allard-Lafarge-Pride (JCALP) semiempirical model. Results from the parametric study guide the design and fabrication of test articles that closely match the initial design requirements. Finally, the fabricated samples are tested using an impedance tube,
and the obtained absorption properties are compared to the a priori numerical predictions. Results indicate that accounting for fabrication defects within the numerical modeling schema can provide reliable sound absorption predictions for additively manufactured porous absorbers.
Effective communication in high opposition project environments
Authors: Goldman Rae , Schad Andrew
Published: June 2023

Though renewable energy is one of the fastest growing industries in the US, local opposition to projects in this sector is increasingly organized, aggressive, and strategic. Using a unified playbook, opposition will often focus on individual disciplines, like noise, in an attempt to
derail a project. To keep up with increasing demand for renewables, it is crucial to prepare for the challenges of project opposition. While soft skills are not always emphasized in formal engineering education, these skills can be equally if not more important than technical knowledge to
counter oppositional tactics. Honing interpersonal skills should be prioritized equally with technical expertise, rather than only being learned through trial and error. We identified communication strategies that we have found effective in the renewables space as well as other high opposition
projects across the acoustics industry. These strategies employ integrity, tact, and conscious relationship building in conjunction with a foundation of industry best practices and technical standards. In sharing this compilation of strategies, we hope to empower engineers of all disciplines
to consider the significance of their role as communicators in effectively overcoming the obstacles that come with developing controversial projects.
Sound attenuation by acoustic metamaterials applied to kitchen hoods
Authors: Plé Jeremy , Kone Tenon Charly , Benchikh Lehocine Allaeddine , Panneton Raymond
Published: June 2023

In a society where the vast majority of people spend their time inside buildings or vehicles, the need to filter the air is essential to ensure a certain level of comfort. The integration of air exchanger systems in these enclosed spaces generates noise pollution which can deteriorate
the quality of the air. Thus, controlling the noise generated by these systems becomes a major challenge for the construction industry. Recent traditional solutions such as acoustic sonic crystals only allow high frequency noise control. One solution is the incorporation of inner structured
acoustic materials for the control of low frequency transmission. This paper proposes a coupling of sonic crystals and structural acoustic materials for the control of sound transmission at low and high frequencies. To achieve this, research and simulations of the acoustic properties of various
metamaterial models under the COMSOL software were established as well as a system of the selected solutions, using the transfer matrix method. Experimental impedance tube analyses are being carried out for varying geometries, along with a fabrication method for prototyping.
Review and Analysis of the Vibration Assessment Procedures Advocated by the Railway Association of Canada
Authors: Busch Todd , Yoong Carlos
Published: June 2023

In the absence of government regulations, the Federation of Canadian Municipalities (FCM) and the Railway Association of Canada (RAC) espouse criteria for the assessment of vibration due to passing trains. Given that many municipalities follow these guidelines when considering the permitting
of residential development, the effectiveness of the RAC vibration assessment methods are worth investigating. These include a limit of 0.14 mm/s RMS on amplitudes and a 75 m screening distance for triggering a detailed study of the impacts of railway vibration on developments in proximity
to tracks. This paper provides a review of the criteria for their reasonableness at avoiding unwanted and/or undesirable vibration conditions for residential developments. This is accomplished through reference to the generic vibration propagation curves within the latest US Federal Railway/Transit
Administrations noise and vibration guidelines and alternative parametric equations for estimating vibration propagation.
Common pitfalls and potential solutions for crypto-currency mining facility noise
Authors: Schad Iliana
Published: June 2023

Crypto-currency mining facilities have become more and more common over the last few years, but there is no standard for construction or noise mitigation for these facilities. Many noise issues are encountered after the facilities are complete and operating. The facilities can contain
thousands of "miners" which can be quite loud. Often, the manufacturers do not supply reliable sound data and the miners themselves are constantly evolving. The miners have extreme power and ventilation requirements which introduce additional noise sources and paths, as well as site
requirements. I have examined the effectiveness of mitigation techniques for these facilities and addressed potential pitfalls for facilities based on similar issues observed across several projects.
Construction Noise Modeling for Solar Projects
Authors: Butterfield Emma
Published: June 2023

The construction of a large solar project typically takes place over a period of 6 to 12 months. Construction is completed under several construction phases, each with a different mix of construction equipment. Due to the large project area where construction is proposed to occur, the
sound exposure of a specific sound sensitive location varies as construction moves throughout the site. For example, road construction for a new access road might use an excavator, dozer, grader, roller, and dump truck. The road construction may or may not happen simultaneously to the trenching
for the new collection route lines. Even if these activities were to happen at the same time, there is the possibility of them occurring on opposite sides of the project area or adjacent to each other. These unknowns make modeling construction noise for a large solar project complicated, especially
during the permitting phase when schedules have not been fully developed. This paper will investigate scenarios used to provide a credible worst-case prediction of construction sound levels throughout a solar project area. Benefits, limitations, and practicality will be discussed.
Case Study: Grocery Exhaust Fan Environmental Noise Mitigation
Authors: Thede Josh
Published: June 2023

This case study highlights a successful project for a grocery store that required exhaust fan outdoor noise control due to a complaint from a residential condominium building across the street. Sound pressure level measurement results are provided for exhaust fan operating conditions
for both before and after the installation of noise mitigation solutions.
Quiet Spacecraft Cabin Ventilation Fan Development: Motivation and Context
Authors: Allen Christopher
Published: June 2023

It is important to control acoustical noise aboard crewed space vehicles and space habitats to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss and annoyance. As with most noise control efforts,
it is best to control the noise at the source, and for spaceflight vehicles these are typically the fans associated with the Environmental Control and Life Support system. These include cabin ventilation fans and intermodule ventilation fans, among others. Throughout the history of crewed
spaceflight, there have been issues with noise from ventilation fans, going back to Apollo. And, with the spaceflight vehicles and habitats currently being developed, there are again concerns with noise from ventilation fans. To address this problem, NASA is working to leverage the technology
developed in its Aeronautics Research Mission Directorate, specifically at the Glenn Research Center, to design highly efficient and quiet fans for reducing community noise levels from civilian aircraft. This paper will discuss the need for transfer of this technology to spaceflight use, and
will discuss the potential benefits, which are significant and will be crucial for the successful development and operations of future spaceflight vehicles, space suits, and habitats.
Deep learning based mechanical fault detection and diagnosis of electric motors using directional characteristics of acoustic signals
Authors: Ippili Srinivasa Rao , Russell Matthew , Wang Peng , Herrin David
Published: June 2023

Early identification of rotating machinery faults is crucial to avoid catastrophic failures upon installation. Contact-based vibration acquisition approaches are traditionally used for the purpose of machine health monitoring and end-of-line quality control. In complex working conditions,
it can be difficult to perform an accurate accelerometer based vibration test. Acoustic signals (sound pressure and particle velocity) also contain important information about the operating state of mechanical equipment and can be used to detect different faults. A deep learning approach,
namely one-dimensional Convolution Neural Networks (1D-CNN) can directly process raw time signals thereby eliminating the human dependance on fault feature extraction. An experimental research study is conducted to test the proposed 1D-CNN methodology on three different electric motor faults.
The results from the study indicate that the fault detection performance from the new acoustic-based method is very effective and thus can be a good replacement to the conventional accelerometer-based methods for detection and diagnosis of mechanical faults in electric motors.
Pickleball Noise & Political Ploys: A Cape Cod Case Study
Authors: Weiss Zachary , Komrower Jeffrey
Published: June 2023

Pickleball is reportedly the fastest growing sport in America, increasing in participation nearly 40% from 2019 to 2021 according to one measure. With this rapid growth, many municipalities have repurposed existing outdoor tennis courts for use as pickleball courts with little consideration
for the increase in noise pollution that often accompanies the change. In contrast to tennis, pickleball employs a solid paddle and hard plastic balls, generating frequent and distinctive noise impulses while in play. Additionally, the speed of play is typically faster with more impulses occurring
more often, and courts can be denser, with two active pickleball courts fitting in the space of one tennis court. This study examines the noise measurements and ensuing politics of a case in Falmouth, MA, where the repurposed tennis courts were located as close as 25 feet from the property
line of abutting residents. Short-term and long-term measurements were taken over a full day of activity and were largely evaluated to the Massachusetts Department of Environment Protection (MADEP) Noise Policy. In periods of high activity, it was found that paddle-ball impulses generated
levels exceeding the MADEP criteria about once every two seconds on abutting properties.
Rezoning - beware of community noise problems
Authors: Barnes James
Published: June 2023

A common mission for an acoustical consultant is to anticipate and minimize noise problems for a community area in transition. Changes and resulting noise problems may be triggered by an industrial area that is rezoned by a city to encourage residential and mixed-use development or
an agricultural area that is rezoned by a town to host light or heavy industry. Either way, potential noise-sensitive receptors, which are usually private residents, may be adversely affected and lodge noise complaints. A specific noise issue is many times compounded by non-acoustic factors
such as traffic, smoke, smell, or visual impacts from the industrial development. This paper discusses historical calls for proper planning to address the goals of interested parties, including industry, government, and community groups, while minimizing the risk of community noise problems.
In addition, this paper describes several examples where rezoning presented challenges and essentially forced industry and community developments to adopt noise control measures.
Considerations for noise control design in retrofit Combined Heat and Power Plants for Healthcare Facilities
Authors: Fennema Laura , Downey Greg , Downey Matthew
Published: June 2023

Combined Heat and Power (CHP) plants have gained popularity in industrial and institutional applications due to their ability to recapture and repurpose wasted heat energy from the power generation process, resulting in significant energy savings and carbon emission reductions. However,
noise control considerations have become increasingly critical in retrofit CHP systems, particularly in healthcare facilities. Often, strict noise performance requirements must be met due to the proximity of residential communities and to ensure a comfortable healing environment for patients.This
technical paper explores critical noise control considerations for retrofit CHP systems in healthcare facilities, focusing on a case study from Hamilton Health Sciences, a healthcare network in Ontario, Canada. The paper examines the design challenges of upgrading the existing CHP plants across
three separate hospitals when addressing stringent sound performance, system ventilation, air tempering, and structural capacity limitations within a limited space. The paper also discusses the unique sound attenuation design solutions implemented to address these challenges.The case study
demonstrates the successful implementation of combining noise control design, ventilation design, and structural design into one integrated solution, specifically to overcome common design challenges in retrofit CHP systems.
Viability of COMSOL within the silencer selection process
Authors: Azar Celine
Published: June 2023

Silencer selection has long been a burdensome, and occasionally iterative process. It is typically done based on tested sound attenuation values obtained using large facilities and costly equipment - making the process time-consuming and unsustainable. Fortunately, Finite Element Analysis
(FEA) continues to become a more viable intermediary step between design and construction. COMSOL Multiphysics(r) is an FEA solver and simulation software. COMSOL's acoustics module can determine full octave decibel values of Transmission Loss.This paper goes through parameters and model setup
in the COMSOL environment as well as the practicality and convenience of using such a software. It also investigates the reliability of such methods of acoustic analysis compared to empirical data, where it may fall short, and identifies areas in need of more analysis.
An adaptive constrained multi-channel active noise control filter design approach using convex cone optimization
Authors: Zhuang Yongjie , Liu Yangfan
Published: June 2023

In current practical active noise control (ANC) applications, solutions to three main technical challenges need to be sought: the requirement of a stable controller when acoustic feedback paths exist, a larger quiet zone, and adaptation to a time-varying environment. The imposed controller
stability constraints can significantly increase the computational requirements and negatively impact the adaptation of ANC filters in real time. Multi-channel systems are usually needed if a larger quiet zone is required while the coupling between different channels can greatly lower the
convergence rate of adaptive algorithms. In the current work, a multi-channel adaptive constrained ANC filter design method is proposed. The recently proposed convex cone formulation for ANC design is adopted to reduce the computational time of solving the constrained ANC filter design problem.
The optimal filter coefficients are then redesigned continuously using convex optimization when the environment is time-varying. The experimental result shows that, compared with the traditional leaky FxLMS method, the proposed method has a faster convergence rate and a better steady-state
noise control performance.
Development of driving test method based on lab test for BSR evaluation of seat-belt subsystem
Authors: Han Je-Heon , Choi Sungwook , Kim Jimin , Son Joo hwan
Published: June 2023

Currently, the BSR (Buzz, Squeak, and Rattle) guideline for the seat belt system is managed only by measuring the dynamic stiffness at the seat belt mount position. It is necessary to improve this experimental method to reflect the actual driving condition. In order to achieve this
improvement, this study determines the driving conditions and road conditions that are easy to reproduce BSR. Then, a lab test-based evaluation method is developed for evaluation convenience. In addition, a single product evaluation method is investigated to establish a test method for manufacturers
of the seatbelt system. In addition, a modal analysis of the seat belt is performed, and structural reinforcement is proposed to improve the BSR.
Occupant-centric acoustical frameworks: Guiding principles to manage background sound
Authors: Koukounian Viken , Moeller Niklas
Published: June 2023

The success of new conceptual frameworks, which center the needs and expectations of occupants in the built environment, is predicated on the development of guiding principles describing the interactions and integration of different acoustical solutions. By way of example, speech privacy
is the assessment of the degree of unintelligibility of speech between a talker and a listener. The evaluation is an equal function of the difference in level of the signal between the source and receiver locations, and the ambient acoustic conditions at the receiver. While there is ample
literature describing strategies for employing acoustical solutions to mitigate the transmission of sound and absorb excess acoustic energy, there are few, if any, that offer guidance as to the interference of noise (emitted from critical building systems) on masking sound (emitted from a
sound masking system) measurement. The proposed conceptual framework relies on acoustical theory to derive new mathematical relationships for effective implementation of sound masking systems. The conditions can enable optimization of the complex relationships implicating building-related
systems' performance and efficiencies, speech privacy and acoustical comfort.
Case study of HVAC noise in a conference room under varying operating conditions
Authors: Buck Adam
Published: June 2023

Conference rooms are acoustically sensitive environments due to the need for high speech intelligibility both in-person and over teleconferencing systems. Room noise from building systems is a key contributing factor to speech intelligibility. Mechanical design, and in turn noise control
design, focuses on peak heating and cooling demand; however, operating conditions vary based on the demand at any given time. This case study presents sound pressure level measurements from a conference room on the top floor of an office building, which was below a mechanical penthouse. The
measurements were guided by ANSI/ASA S12.2, "Criteria for Evaluating Room Noise." Commissioning and developer agents varied the operating conditions of the entire building heating and cooling system to identify the primary contributors to room noise levels in the conference room,
which varied as much as 13 dBA over background. Particular attention is given to the correlation between room noise levels and airflow from the air terminal unit serving the space. Comparisons between measured noise levels and noise modeling predictions are also provided.
Structural and architectural isolation methods for incompatible programming adjacencies
Authors: Ormsbee Caitlin
Published: June 2023

Although Burbank, California has long been touted as the "Media Capital of the World", there is certainly an argument to be made that New York City is the true Media hub. Broadcasting companies are expanding their footprint building new studios, and non-media companies are
expanding to include in-house broadcasting capabilities. Unfortunately, while broadcast studios, recording booths, and production spaces typically require very low noise levels, New York City is also known for its boisterous hustle and bustle. We will review a case study involving Live Broadcast
Studios and product spaces being constructed at a sub-cellar level adjacent to the New York City MTA Subway tunnel. Several studies were conducted prior to construction to determine the appropriate whole building and structural isolation measures for the project. Simulations were then used
to demonstrate expected noise levels to the client to inform decision making. Given the project cost and expectations, additional measurements are being taken through construction to confirm and track reduced vibration and noise levels.
Vibration Isolation with Spring Supported Concrete Floating Floors on Fitness Centers
Authors: Tigli Omer , Royvaran Mohammad
Published: June 2023

Spring-supported concrete floating floors are often used as a high-end solution to mitigate noise and vibration disturbances in fitness centers. Suppliers of these floors typically provide impressive sound test results, but information regarding their low-frequency vibration isolation
capabilities is scarce. In this study, the authors collected in-situ vibration data from an existing fitness center equipped with a 4-in (102-mm) thick spring-supported concrete floating floor while conducting various activities such as running on a treadmill, dropping a dumbbell, putting
down a barbell and slamming a medicine ball on the floor. Frequency measurements revealed that entrapped air led to an increase in the natural frequency of the floating floor. The data demonstrated that floating slab effectively isolated noise and high-frequency vibrations, but was not able
to isolate low-frequency vibrations. Additionally, a finite element model of the structure was developed, incorporating the floating floor and the base structural slab. The model was used to simulate treadmill running and weight drops, and calculated vibration levels were presented as heat
maps across the entire floor. The model's predictions aligned closely with the actual measurements, demonstrating that vibration analysis based on finite element models is a valuable method to design effective mitigation strategies for fitness centers.
Empirical validation of an angle-error model for computing free-field sound power using a cylindrical enveloping surface
Authors: Bard Seth
Published: June 2023

The angle error inherently biases the calculated sound power level when determined using free-field sound pressure level measurements over an enveloping surface. A regression equation was previously created to predict the angle error associated with omnidirectional sources using just
a few easily obtainable input variables related to the geometry of the source and the enveloping measurement surface. This paper assesses the accuracy of that predictive regression equation through an empirical study. A dodecahedron loudspeaker was used as a noise source over a range of positions
within the reference box. The modeled angle error correction was applied to the computed sound power levels using measurement data from multiple cylindrical enveloping surfaces in accordance with ISO 3744 and ISO 7779. The corrected sound power levels were compared to the measured sound power
levels of the source per ISO 3741 direct and comparison methods.
Validation of the Computational Aeroacoustic Simulation of a Subsonic Jet tailpipe Flow Noise
Authors: Donkin Seth , Herrin David
Published: June 2023

A case study in the application of computational aeroacoustics in the prediction of flow noise from a subsonic jet generated at the tailpipe of a straight pipe. The simulation is completed using a hybrid approach. The results from a Large Eddy Simulation completed using are used to
formulate acoustic sources. These acoustic sources are formulated using Lighthill's analogy and then mapped onto an acoustic finite element mesh using the tools built into the acoustic FEM software Actran. The total predicted sound power of the sources inside the pipe and the turbulent jet
region are then validated to completed acoustic measurement using the University of Kentucky's muffler flow test rig.
A hybrid transfer function procedure for broadband auralization within small flight vehicle interiors
Authors: Allen Albert , Krishnamurthy Siddhartha
Published: June 2023

Auralization of the sound fields within flight vehicle interiors is of interest to aircraft designers considering crew and passenger ride quality. Computer models can be used to predict the filtering effects that the fuselage structure and interior volume have on the exterior sound
field in order to simulate the resulting cabin interior noise. However, this can become expensive when a wide frequency range of analysis suitable for passenger auralization is desired. This is particularly the case when using deterministic modeling methods such as finite element analysis
(FEA) wherein prohibitively high levels of detail and finite element discretizations are required to resolve the wavelengths at high frequencies. On the contrary, Statistical Energy Analysis (SEA), while not capturing important modal behaviors at low frequencies, is better suited for higher
frequency analyses where structural and interior dynamics exhibit high modal overlap and spatially averaged physical quantities suffice. For this reason, a hybrid procedure is considered here that utilizes FE modal solutions at lower frequencies and SEA results at higher frequencies. A transfer
function dataset containing the exterior to interior vibroacoustic filtering effect is calculated accordingly and subsequently stored to be used for a variety of exterior dynamic load cases. At low frequencies, the transfer function dataset detail is related to the level of
Force amplification at the wheel hub due to the split in the air-cavity mode for a rolling tire
Authors: Choi Won Hong , Choo Kyosung , Bolton J.
Published: June 2023

Reduction of tire/road noise has become an important issue for EV's since powertrain noise has largely been eliminated. A tire's air-cavity mode is known to be a significant contributor to increased forces at the wheel hub, which can result in significant interior noise levels near
200 Hz. Moreover, the single natural frequency of a static, undeformed tire can separate into two neighboring frequencies for a rolling, deformed tire due to the Doppler effect. In this study, the evolution of the frequency split at different speeds was observed in Tire Pavement Test Apparatus
(TPTA) tests by measuring the dynamic force at the hub under rotation and load. Similar results were obtained using FE simulations to generate Campbell diagrams. Through the FE simulation, it has been shown that there can be force amplification at the hub when the split frequencies couple
with adjacent treadband structural modes near 200 Hz. In addition, both material and geometrical modifications were applied to the base model to find values that would reduce force levels at the split frequencies. Finally, it is suggested that a target speed needs to be determined when evaluating
a tire since the two natural frequencies are strongly influenced by rotation speed.
Unregulated Warehouse Truck Traffic and Mitigating Community Noise Impacts
Authors: Wallace Marc , Riegert Matthew
Published: June 2023

It seems that every year more and more warehouse construction, and the promise of more heavy truck traffic, is occurring across North America. And although U.S. Federal noise standards ensure mitigation of highway truck traffic, when necessary, they are not applicable to more heavy
truck traffic on local roads associated with a new warehouse development. Furthermore, most local, and state noise regulations focus on stationary sources and typically do not include enforcement of prescribed noise limits for on-road trucks. And the development of new warehouse developments
in suburban and rural areas has amplified community concerns of noise (and air quality) associated with heavy truck traffic on local roads. This paper will include a discussion of the sources of sound associated with a typical new warehouse development, which sources are most concerning to
suburban and rural communities based upon recent experiences, how they are typically regulated, what sound level metrics can be used for evaluating those sources, how they can be modeled and mitigated, and how a proactive approach to noise mitigation can lead to the successful approval of
a new warehouse project and consensus of the community.
Use of the noise-free interval (NFI) metric to assess the disturbances of airborne vessel noise at Glacier Bay National Park
Authors: Poling Jacob , Betchkal Davyd
Published: June 2023

Alaska's Glacier Bay National Park preserves the seventh largest unit of the National Wilderness Preservation System, encompassing 2.6 million acres. Natural acoustic environments are significant to many of the unit's fundamental resources and values. Since 2001, the National Park Service
has inventoried acoustic environments of Alaskan parks. One purpose is to document every noise-free interval (NFI) observed. NFI is defined as the time between human-generated noise disturbances. Aggregate properties of NFIs describe fragmentation of acoustic environments by noise. Median
NFI estimated at parks in Alaska to date range from < 3 minutes to 16.7 hours, similar to other Arctic sites (0.5 to 13.0 hours, Stinchcomb et al. 2020). For the Glacier Bay Marine Management Plan Environmental Assessment, a geometric NFI model was developed using automatic identification
system (AIS) derived vessel tracks. The NFI simulation results, along with NFI data from acoustic monitoring at the park, was then utilized to assess how changes to vessel quotas and vessel management strategies would potentially affect the NFI throughout the park. This paper will discuss
the estimation and use of the NFI metric in protected natural areas, along with NFI modeling methods utilized for an environmental assessment at Glacier Bay.
Trends in the development of measurement microphones
Authors: Rasmussen Per
Published: June 2023

Measurement microphones are, in principle, simple transducers that convert dynamic pressure fluctuations into an electrical output signal. The range of applications is, however, extremely wide-from measuring exceptionally low-level signals (below 0 dB; for example, measuring tiny insects)
to the 190 dB signal of large rocket launches. The frequency range of interest spans from below 0.1 Hz for sonic boom measurements to 200 kHz or more for detailed investigations of very short impulses or wind tunnel scale modelling. At the same time, the individual application may mandate
specific mounting conditions with specialized form factors for the microphone and associated preamplifier design. This trend towards application-specific testing has led to the development of a wide range of specialized microphones and accessories. Still, this wide variety of measurement microphones
must measure accurately and be calibrated to be traceable to the basic unit of measure as, for example, defined by the SI system. This is ensured by maintaining reference to the basic IEC definition of measurement microphones in the IEC 61094 series of standards for microphones and calibration
methods.
Characterizing elastic parameters of isotropic thin plates using impedance tube and transmission loss measurements: a numerical inverse method
Authors: Verdiere Kevin , Campeau Simon , Biboud Julien
Published: June 2023

Thin plates are widely used in various engineering applications, including aerospace, automotive, and construction industries. The mechanical properties of these plates, such as Young's modulus, Poisson's ratio, and structural damping, are essential in determining their acoustic performance.
While there are various methods for measuring these properties individually or simultaneously, accurately obtaining them can be difficult due to the thin plate's delicate structure and the need for high precision and sensitive equipment. In this paper, we present a numerical inverse method
for characterizing the elastic parameters of isotropic thin plates using transmission loss measurements obtained from an impedance tube and clamped circular specimen. The proposed method is compared to the Oberst beam technique (ASTM E756-05), and demonstrated through several examples ultimately
allowing for the prediction of diffused field transmission loss obtained through intensity measurements in a small reverberant room.
Dual layered light weight fire resistant PU foam-based composite for acoustical insulation
Authors: Banka Navin , Chatterjee Debasish
Published: June 2023

In today's automotive industry, sound package design and optimization is important considering the mounting need for weight reduction and achieving targeted sound absorption and sound transmission loss values. The present paper relates to dual layered light weight (LW) fire resistant
(FR) Polyurethane (PU) foam-based composite for engine room insulation, referred herein as Ωµ2 foam comprising of two layers of foam having different densities and flexibility. The composite consists of one layer of semirigid FR PU foam acting as a carrier with sound absorptive property
and another layer consisting of flexible FR PU foam acting as higher acoustical absorptive property. This concept is intended for enhancement of acoustical performance by the synergistic effect of dual foam layers besides being FR and LW material, specially designed for passenger vehicles'
engine compartment insulations such as firewall/dash panel, bonnet/hood liner insulation and other diverse applications in commercial vehicles. The paper presents material properties and in-depth comparative assessment of sound absorption properties of dual layer (Ωµ2) LW FR PU foam
with respect to conventional materials like single layer light weight semi-rigid PU foam and resinated cotton shoddy felt, etc.
Non-contact vibration transmissibility measurements of an additively manufactured pentamode material
Authors: Cushing Colby , Kelsten Matthew , Haberman Michael , Wilson Preston , Norris Andrew
Published: June 2023

Pentamodal (PM) metamaterials are elastic structures that are designed to support purely longitudinal acoustic wave propagation over a wide band of frequencies. Further, these metamaterials can be designed to have anisotropic stiffness and be impedance matched to water [doi.org/10.1121/10.0009161].
Due to the complexity of three-dimensional (3D) PM microstructures, metal additive manufacturing techniques must be employed to physically realize these materials to achieve the specifically tailored impedance and anisotropic sound speeds over the desired frequency range. Previous work designed
and built an additively manufactured titanium PM material measuring 98.9x 98.7x87.2 mm3 which was successfully characterized in a fresh-water tank. The current work presents vibration transmissibility measurements on the same PM sample. The structure was mounted on an electro-dynamic shaker
which provided a broadband base excitation. Base acceleration and out-of-plane surface accelerations of each exposed face were then measured using point accelerometers and a scanning laser Doppler vibrometer, respectively, and the process was repeated for multiple sample orientations. The
observed vibrational modes demonstrate the influence of geometric asymmetry introduced by the truncated domain of the PM lattice. Measurements were compared to a fully-featured finite element model of the sample using COMSOL Multiphysics showing good agreement in mode shapes. [Work supported
by ONR]
The 47-Year history of the City of Portland, Oregon's noise review board and its successful model of addressing community noise issues
Authors: Van Orden Paul , Standlee Kerrie
Published: June 2023

The City of Portland Oregon has a successful history of over 40 years of operating a quasi-judicial Noise Review Board to help address and resolve urban environmental noise pollution. This paper explores the successes and failures of the unique Noise Review Board. The paper notes the
potential for use of this governmental approach to address community noise in other large and medium sized cities. The Portland Noise Review Board is 6 members. It includes three technical professionals and three citizens at large to collaborate on noise in the urban environment. The technical
professionals are 1) a professional in the Acoustical Sciences 2) A professional from the construction industry, and 3) the acoustical expert for the City of Portland , their Noise Control Officer. The Noise Control Officer is a non-voting member and staffs the government board. The five voting
members administer quasi-judicial code decisions and offer the City's elected officials an experienced body to address environmental noise issues. The Noise Review Board plays a key role in the urban planning of Portland by offering guidance to the City Council on emerging sources of noise
pollution, such as garbage trucks, leaf blowers, outdoor concert venues, and the Portland International Raceway.
Warehouse and distribution center cold storage outdoor noise assessment
Authors: Storm Mark
Published: June 2023

Although "warehouse" and "distribution center" terms may be used interchangeably by many, cooling load demand for these kinds of storage facilities can vary widely and requires a range of heating, ventilating, and air-conditioning (HVAC) solutions. Furthermore, incorporation
of on-site cold storage capability can greatly amplify the net cooling load of a facility and its corresponding HVAC system with necessary outdoor-exposed noise-generating sources. This paper presents a sample predictive outdoor noise assessment of a facility that features cold storage, and
includes key considerations for modeling setup, outdoor noise level assessment with respect to applicable jurisdictional thresholds, and noise reduction recommendations that may be common to warehouses or unique to cold storage facilities.
Towards high-quality X-59 sonic thump measurements
Authors: Anderson Mark , Gee Kent , Durrant Jeffrey , Loubeau Alexandra
Published: June 2023

Brigham Young University has been studying questions related to NASA X-59 community noise testing. A summary of the key findings and recommendations to date are presented. Among these are weather-resistant ground microphone setups that reduce wind noise, methods for treating the problem
of ambient noise contamination on sonic boom metrics and spectra, and the turbulence-induced variability seen over relatively small-aperture arrays. Also discussed are recommendations for data post-processing, e.g., employing a digital pole-shifting filter and zero-padding to improve the fidelity
and smoothness of low-frequency spectral data. Finally, the relative merits of various sonic boom metrics are considered. Although Perceived Level has been the most widely-used metric, it is relatively sensitive to ambient noise contamination and turbulence-induced variability. [Work supported
by NASA Langley Research Center through the National Institute of Aerospace.]
Soundproofing Autonomous Vehicle Computers for Passenger Comfort
Authors: Wang Yawen , Everett Ross , Johnson Bret , Roney Grant , McDonald Nicholas , Alejandre Fernando , Yonan Amir
Published: June 2023

The computing superstructure necessary for self-driving cars to function presents a unique acoustics problem - the fans produce significant amounts of noise within the cabin that is uncomfortable for passengers. To ensure consumer comfort and promote more widespread adoption of the
technology, soundproofing is required. Any soundproofing solution must not compromise the ability of the self-driving computer to function, meaning that air flow must be preserved. To this end, the UTA Senior Design team creates testing procedures to identify the sound profile of May Mobility's
Toyota Sienna. After identifying the frequency range and intensity of the fan noise within the cabin, the team can narrow down potential soundproofing solutions. Given the noise frequency range and air flow requirements, three materials that show promise are identified. The team's testing
of varying configurations of cork, open-cell charcoal foam, and closed-cell neoprene foam to determine the most effective solution resulted in the identification of charcoal foam as the optimal material. Soundproofing structures were strategically placed around the computing superstructure
and achieved a noticeable reduction of noise within the cabin.
A sound isolation case study for Detroit Metro Airport's TSA K-9 unit break room
Authors: Catton Anna , Kachur Mandy
Published: June 2023

The renovation of Transportation Security Administration offices at Detroit Metro Airport included a new K-9 break room for handlers to file reports and for their furry partners to decompress between explosives detection sniffing patrols. Post-renovation, the (human) occupants complained
of excessive noise due to luggage conveyer belts located in the ceiling plenum. Soundscape Engineering conducted an assessment to determine feasible noise mitigation solutions to increase acoustical comfort in the break room. The primary noise source was the spiral power turn conveyer and
its four motors. With the implementation of gypsum-backed ceiling tiles, an insertion loss of 17 dBA was realized. Despite the NC 57 environment in the room, the noise reduction earned rave reviews from its bipedal users. This paper discusses the budgetary, performance, and scheduling considerations
for the barrier ceiling solutions and the resulting improvements obtained in the K-9 break room.
Marine mammal protection from impulsive noise
Authors: Cox Kenneth
Published: June 2023

In this presentation we will look at the metrics used by the National Marine Fisheries Service (NMFS) for determining noise exposure levels for marine mammals and fish from the effects of underwater impulsive noise. A common source of impulsive underwater noise is pile driving associated
with activities such as bridge or pier construction or the anchoring of offshore structures. A portable measurement system that allows in field measurement verification and also provides results quickly will also be presented.
18 dB Noise Control for $0 Capital Expense
Authors: Fullerton Jeff
Published: June 2023

In metropolitan areas, new laboratory and research facilities are expanding closer to residential areas and creating sound emissions conflicts between these two groups. A recent project that revitalized an old, unused warehouse into a new laboratory facility for cutting-edge research
required significant exterior ventilation and cooling equipment. Extensive consulting was performed to confirm that the design and future installation of the facility would comply with local regulations. However, during startup of the systems, neighbors raised concerns about the sound emissions
from the new equipment. Studies of the sound emissions from the commissioned equipment identified a significant tone emanating from the facility. Adjustments to the control systems for the equipment eliminated the tonal noise for no capital expense and reduced the neighbor's concerns. Discussion
of these adjustments will be presented in this paper.
Challenges in Modeling Environmental Noise From Boats
Authors: Casey Tim , Copenhaver Benjamin
Published: June 2023

Boats have characteristics that are unlike other surface transportation modes, and many of them make it challenging to model environmental noise emissions from boating activiteis. This paper discusses some of the challenges associated with modeling environmental noise from boats.
Background Sound Levels in Rural Areas of the U.S.
Authors: Kaliski Kenneth , Rost Hugo , Schomer Paul
Published: June 2023

ANSI S12.9 Part 3 Annex C provides a compilation of the average daytime, nighttime, and day-night sound levels in six land use categories, ranging from Category 1 - "very noisy urban residential" to Category 6 - "very quiet suburban and rural residential." However,
the data in table C.1 of the standard, which provides typical day, night, and day-night sound levels by land use category, is based primarily on more urbanized areas, and provides caution in using the data for the less densely developed land use Categories 5 and 6. In this paper we supplement
this Annex by providing a collection of ambient sound level data at over 150 rural locations primarily in the northeastern and midwestern U.S. As the ambient sound level is not a single metric, the results include the range of sound levels in various metrics, including the A-weighted L10,
L50, L90, and Leq, for the daytime and nighttime, and DNL. Unweighted octave and 1/3 octave band ranges and averages are also presented for each metric. Where possible, we also compare these results at individual locations to the predictions made by national noise mapping programs.
Highway Noise Abatement - Not Just Barriers
Authors: Wayson Roger , Porter Christopher , Varela-Margolles Aileen
Published: June 2023

Noise from transportation sources is considered a primary source of annoyance world-wide. Highways are the most ubiquitous and as such, abatement of highway noise is an on-going concern. Recently, work was completed for the Federal Highway Administration including "Framework for
Considering the Benefits and cost of Noise Abatement Measures" and "State of the Practice-Evaluating and Quantifying the Benefits of Noise Abatement Measures: Literature Review and Synthesis". Abatement measures reviewed covered a wide range of possible methods that could be
utilized. Information from these documents, based on an international literature review and then used in a cost/benefit analysis procedure, will be presented and important measures discussed.