bluuebunny/crossref_metadata_2025 huggingface dataset:
Reducing targeted low frequency railway noise with precast modular sound absorbers
Authors: Figallo Gary Stephen , Pruden Michael
Published: July 2024

This paper investigates the noise profile of modern railway systems and introduces a sound-absorptive precast modular block comprised of multiple materials and volumes. The components and configurations are selected in a specific manner such that each volume of material has a sufficiently
different and complimentary sound absorption profile. The resulting system provides better overall sound absorption of railway noise while targeting specific frequencies of interest (typically low frequencies). The effectiveness of sound attenuation requires the railway noise to transmit through
the outer volume material and into the inner volume material. Practical and environmental considerations require materials that can be utilized in large-scale manufacturing operations and result in a modular system that is price-competitive, relatively light-weight, easy to install, durable,
and made from recycled materials.
Multilayer ceramic capacitor induced audible noise simulation
Authors: Wu William , Hua Xin , Wang John , Chang Wei-Chan
Published: July 2024

Multilayer ceramic capacitors (MLCCs) are one of the most widely used capacitors. Their small size, high capacitance, high reliability and low cost make them ideal for miniaturized electronic devices. However, their piezoelectric effect may cause the deformation of the capacitor associated
with the applied voltage. Even worse, the deformation may cause the PCB vibration and potential noise radiation, which can be a problem for devices designed to be quiet, such as cellphones, earbuds, laptops, etc. This paper introduces how MLCCs can cause PCB vibration and noise radiation problems
by simulating a single MLCC with piezoelectric effect. And then, a methodology is proposed on how to quantify the MLCC as vibration load source. Moreover, a simplified process is illustrated to simulate the MLCC induced noise radiated from circuit boards. Finally, a couple applications are
demonstrated by using the developed process.
Extrapolation of transformer equipment noise from excessive background noise environment
Authors: Brenneman Robert M.
Published: July 2024

Dynamic, high relative background noise environments present challenging measurement conditions for discerning the noise level contributions for equipment of interest, particularly in circumstances where equipment cannot ideally be shut down for baseline measurement comparison. This
paper considers the evaluation of large transformer noise emissions contributions in excessive background noise conditions for purposes of property line compliance assessment, exemplifying such an occurrence. While often insufficient alone, typical field measurements may be accompanied by
fundamental, but powerful, narrowband signal analysis techniques to estimate and demonstrate equipment noise contributions, especially for sources containing prominent tonal components, such as those that are common to electrical equipment. This simple and straightforward approach focusing
on calculation of average spectral densities and use of spectrograms, supplemented by other analysis tools including three-dimensional environmental noise modeling as was employed in this case study, offers an efficient and effective equipment noise assessment strategy that may be readily
applied by the practitioner.
Trends and relationships between airport operations and noise complaints in Maryland between 2016 and 2023
Authors: Abiodun Pelumi O. , Olude Adebayo Iyanuoluwa , Owolabi Oludare , Darko Cornelius
Published: July 2024

The noise pollution from aircraft near airports significantly affects the health and quality of life of the local community either near or far away. This study analyzes trends in airport noise complaints in Maryland from 2016-2018. Data on noise complaints were extracted from airport
noise quarterly reports and the data included the number of complaints and unique complaints from different communities near airports, as well as average aircraft operations. The number of complaints rose from less than 1,000 in 2016 to nearly 10,000 in 2018. This study aims to identify the
communities most impacted by increasing airport noise through descriptive and geospatial analysis of complaint data. Results will highlight high-complaint areas to inform future noise mitigation policies and airport expansions in Maryland. The number of noise complaints increased drastically
from 2016-2018, while flight operations remained steady. Correlational analyses examine the strength of relationship between flight volume and complaint volume over time. Boeing 737-700 operations has the most significant relationship with the number of unique complainants around Baltimore/Washington
International Airport. Results will help inform policies to mitigate noise impacts by identifying whether reducing operations, changing flight paths, or other strategies could effectively reduce complaints as well as help the meeting the noise reduction design goals of the state.
Acoustic measurement of super-small-particle-filtering stainless steel wire cloths
Authors: Zhou Hao , Wu T. W. , Herrin David W.
Published: July 2024

The super-small-particle-filtering stainless steel (SSPFSS) wire cloth can serve as a front cover on resonators in mufflers, offering a broader noise reduction bandwidth compared to the resonators themselves. Like micro perforated panels (MPP), the SSPFSS wire cloth provides flexibility
in resonator design and manufacturing. In this study, we conduct measurements of the transfer impedance of SSPFSS cloths and sound absorption coefficients of absorbers covered by SSPFSS cloths. For comparison purposes, we also calculate the sound absorption coefficient of foam and various
absorbers covered by MPP, traditional perforated panels, and fabric using referenced empirical equations.
Retrospective Cost Saving Comparison Between TNM 2.5 and TNM 3.2 Barrier Analysis Results
Authors: Martin Cole , Moore Hunter
Published: July 2024

In December of 2021, the Federal Highway Administration (FHWA) Traffic Noise Model (TNM) version 3.1 was released to the public for use on traffic noise projects and subsequently updated to version 3.2 in December 2023. However, most or all state Departments of Transportation (DOT)
continue to accept and prefer the use of TNM 2.5 (released in 2004). A presentation at NoiseCon 2023 (TNM 2.5 vs TNM 3.1 Noise Level Prediction Comparison by Mukul Pal and Michael Parsons) came to the conclusion that, generally, TNM 2.5 tends to overpredict traffic noise levels in comparison
to the TNM 3.1, resulting in additional impacts and subsequent additional mitigation that may not be necessary when analyzed with the updated algorithms. In this paper, the authors determine potential cost savings by migrating from TNM 2.5 to TNM 3.2 by comparing results from previously approved
traffic noise projects. By determining the potential cost savings of a migration, DOTs may be better informed about whether or not they should continue to utilize TNM 2.5 or make the transition to TNM 3.2.
Challenges in Urban Data Center Design
Authors: Hamilton Scott
Published: July 2024

The data center market is experiencing significant growth, with each new facility requiring increased power density and cooling needs. This growth brings new challenges, including noise pollution and its impact on nearby communities, which becomes excessively difficult in urban environments.
This presentation will explore the issues faced by data centers in urban environments and discuss potential solutions to create quieter facilities. Key points include: Physical challenges: Every site design faces numerous physical constraints, including limited rooftop and equipment room space,
tight and complex adjacencies of neighboring sites, and design and performance standards for equipment. Political issues: Every site and community have a different set of laws and regulations that a site needs to meet, and often go beyond to ensure that the community will accept the site.
People issues: Data centers must navigate contentious relationships with neighbors and address noise concerns to maintain a positive reputation. By addressing these challenges, data centers can minimize noise pollution and maintain positive relationships with surrounding communities, ensuring
a sustainable future for the industry in urban environments.
Noise control tactics to balance the demand for sustainable energy storage, community tranquility, and environmental regulatory compliance
Authors: Segovia Nicholas A. , Burke Connor
Published: July 2024

As the construction of large-scale Battery Energy Storage System (BESS) facilities increases in California, their impact on urban sprawl is also becoming more pronounced. Projects involving BESS arrangements increasingly find themselves within or near residential land uses in California,
providing greater challenges for noise control and abatement to comply with state and local operational noise thresholds. This paper presents case studies of what Dudek has found to be the most efficient noise control tactics related to lowering the noise emission of BESS facilities, particularly
through the implementation of onsite noise walls, direct noise attenuation applied to BESS equipment (i.e., noise attenuation for battery thermal management systems involving the operation of ventilation fans and refrigeration system components), and modified BESS equipment arrangements. These
strategies are essential for ensuring that BESS projects are not only compliant with environmental standards but also socially acceptable within residential communities. By presenting practical and efficient noise mitigation techniques, this paper aims to guide planners and developers in the
sustainable development of BESS facilities, balancing the demand for energy storage with the preservation of community tranquility and compliance with regulatory noise limits.
Assessing wayside traffic noise levels using long-term noise monitoring and available Department of Transportation traffic data - worst-case noise traffic conditions, effects of repaving, and methods for comparing traffic noise data sets
Authors: Higginson Jonathan
Published: July 2024

The availability of automated continuous traffic data from State Departments of Transportation (DOTs), such as the California Department of Transportation (Caltrans) Performance Measurement System (PeMS), provides increased opportunities for the analysis of highway noise. Traffic data
that is free to access and downloadable via the internet can be matched with unattended long-term noise measurement data to provide large datasets for analysis, without requiring field staff to be continuously on site. A 2018 ICF/Caltrans paper documented how this approach was used on an operating
freeway to determine the volume of traffic that results in the highest one-hour energy average traffic noise level. At the time of those measurements, the subject freeway had Portland cement concrete pavement. The freeway has since been repaved with an open-graded rubberized asphalt concrete
pavement overlay. The current study uses new (2023) traffic noise measurements and PeMS data to investigate how worst-noise conditions have changed and the effect of the repaving on wayside noise levels. Changes in traffic patterns since 2018 required the authors to normalize the measurement
data for comparison. Opportunities were identified to take advantage of the large measurement data sets to match before-and-after data, and those methods are also described in this paper.
Noise considerations for the distributed modular-based approach to cryptocurrency data centers
Authors: Puckett Brian , Ginter Vince
Published: July 2024

While the establishment of cryptocurrency data centers becomes increasingly prevalent, the significant noise impact of these facilities on the surrounding community and environment has also become of interest. One of the most common designs for cryptocurrency mining facilities is to
utilize a set of modular data centers, commonly constructed out of modified shipping containers, which are distributed over a large space. Each individual data center module can contain a large number of cryptocurrency mining computers, with each of these equipped with its own cooling fan
system. The individual miner fans, coupled with the large ventilation fans required to cool the data center modules themselves, can lead to a complex, widespread acoustic environment that can be difficult to mitigate. This work presents commonly implemented noise mitigation strategies for
cryptocurrency mining operations and the common issues that come along with those strategies, as well as operational limitations that must be considered when designing the proper noise control solution. Applications to regulatory constraints on noise, or lack thereof, are discussed.
Investigation of methods to estimate NLR of residential structures for airport sound insulation programs
Authors: Cox Eric , Jubera Hayden
Published: July 2024

This paper investigates methods to estimate outdoor-to-indoor noise level reduction (NLR) for single family residential structures before and after the installation of sound insulation treatments to improve the structure's NLR. Acoustical modeling results and Outdoor-Indoor Transmission
Class (OITC) ratings are evaluated in the context of treatment design for airport sound insulation programs and assessment of soundproofing product performance. Overall, post-construction NLR predictions are observed to have a high degree of accuracy when the results are generated using a
combination of pre-construction measurement data and acoustical modeling techniques. The composite OITC rating of the noise exposed building façade is also shown to be an effective metric for predicting NLR values.
The pickleball seven decibel challenge
Authors: Storm Mark
Published: July 2024

Noise emission from outdoor pickleball play and its potential impact to surrounding community receptors is often characterized as an impulsive source of sound, which would be consistent with ISO 1996-1 definition for a regular impulsive sound source that includes "outdoor ball
games" as an example. But some recent noise assessments including those that may be found online are leaning towards elevating pickleball noise emission to the highly impulsive category and thus affording it a 12 dB adjustment instead of the 5 dB adjustment for regular impulsive noise--hence,
a 7 dB difference that if confirmed would make pickleball noise compliance with applicable community regulations and policies much more difficult. This paper elaborates on the impulse noise category distinction as it may apply to pickleball play, and summarizes apparent support (or lack thereof)
to cross the seven-decibel divide and how that might influence court development growth for the rapidly growing pickleball sport and potentially affected neighboring communities.
Exploring the potential of recycled polypropylene-waste jute fiber composites for sound insulation: An experimental and theoretical analysis
Authors: Mago Jonty , Jaish Sunali , Negi Ashutosh , Bolton J. Stuart , Fatim S
Published: July 2024

This study explores the potential of panels made from Recycled Polypropylene (RPP) and Waste Jute Fiber (WJF) for sound insulation applications. Two types of panels were fabricated by the compression molding process: Neat RPP and a composite of RPP reinforced with a WJF interlayer (RPP/WJF/RPP).
The physical properties, namely density and mechanical properties, such as tensile strength and modulus, were examined for both panels. The vibration properties of the panels were evaluated through a modal analysis conducted according to ASTM E756-05 guidelines, while sound insulation was
assessed by measuring normal incidence sound transmission loss (STL) using a four-microphone impedance-tube setup following ASTM E2611-19 standards. The RPP/WJF/RPP composite, with a density of 913 kg/m³, is 2.47% higher than that of Neat RPP, which is 891 kg/m³, and exhibited an
increased tensile strength of 12.01 MPa, compared to 10.03 MPa for Neat RPP. In the second vibration mode, the composite's damping ratio of 3.62% outperformed Neat RPP's 2.48%. Furthermore, the composite's measured average STL was 38.6 dB, exceeding the Neat RPP's average of 37.7 dB. This
enhancement in STL is likely attributed to the composite's higher surface density (5.21 kg/m²) relative to Neat RPP (4.72 kg/m²), contributing to its improved sound insulation properties. The theoretical average STL values, predicted using the Mass
Industrial centrifugal gas compressor sound emission comparison across speed lines
Authors: Fuzak Corey
Published: July 2024

Centrifugal gas compressors are widely used in the oil and gas industry. Gas compressors produce sound emissions while operating and are often unenclosed requiring the need to know the sound emissions. Gas compressors create a variety of sound pressure levels across their large operating
range. This paper compares sound pressure levels of a compressor operating across three different speed lines and two different pressures. The results show increasing sound levels coincide with increasing mechanical power. Also shown is an increase in sound level as the compressor approaches
choke.
Vibration performance of isolated slab concepts in laboratory settings
Authors: Rynberg Tyler , Davis Byron
Published: July 2024

The "isolated" or island foundation concept is commonly used at high-end imaging suites (SEM, TEM, SPM, NMR), with the goal of reducing vibration at sensitive instrumentation. The operating theory is that, by separating the foundation supporting the instrument from the rest
of the building foundation, the transmission of vibrations from environmental, mechanical, and other local sources, will be reduced. But is this concept truly effective at reducing vibration transmission from all or any of these sources? And if so, are the benefits present over the entire
frequency range of interest or only limited to a narrow range of frequencies? This paper discusses the vibration performance of the island foundation concept and presents field data collected in four different settings. Data from three national laboratories and a commercial science facility
are used to illustrate the benefits and disadvantages of this concept, in both the vertical and horizontal directions, for environmental, mechanical, and other local sources.
Enhancing the absorption performance of minimal surface-based bulk absorbers via symmetry-breaking
Authors: Godakawela Janith , Carrillo-Munoz Maria , Sharma Bhisham
Published: July 2024

The examination of Triply Periodic Minimal Surfaces (TPMSs) in the context of their acoustic dampening qualities has established them as viable alternatives to conventional porous absorbers. By adjusting the structure's porosity, one can significantly alter the TPMSs' acoustic absorption
characteristics. Traditionally, enhancing sound absorption has involved decreasing porosity, which unfortunately increases the material's weight. In this study, we introduce a different approach to alter their absorption performance without altering their overall relative density. Our approach
relies on leveraging the mathematical formulation of such structures to break their underlying geometrical symmetry. This symmetry-breaking results in altering their sound absorption characteristics while introducing an anisotropic acoustic response. In this paper, we present the mathematical
design and fabricate the samples using the Fused Filament Fabrication (FFF) additive manufacturing method. The sound absorption characteristics of the printed samples are tested using a two-microphone normal incidence impedance tube setup. The presented results demonstrate that symmetry-breaking
provides a viable route towards improving the low-frequency response of TPMS sound absorbers.
Prediction to Reality, Leveraging modeling to speed solution development
Authors: Herreman Kevin
Published: July 2024

When developing a noise control solution, it is beneficial to provide modeling of the system to optimize the resulting solution limiting testing to relevant solutions meeting the various constraint requirements of cost, performance, manufacturing, and shipping. A recent study on predicting
sound transmission through vehicle panels to eliminate the multiplicity of testing needed to identify the best solution. This paper will present a study to identify a solution to improvement of the sound transmission of a vehicle panel leveraging modeling and comparing the model results to
the actual test results. by comparing model predictions to test results from ASTM E90 - Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements1. Vehicle panels featuring distinct absorbing configurations identified through modeling
were installed within a composite plug wall and subjected to standardized acoustic excitation. The agreement between model predictions and experimental data will demonstrate effectiveness of models in predicting panel performance.
Determination of diffuse field sound absorption of a porous absorber from Biot parameters using simulation
Authors: Neihguk David , Herrin David W. , Hadjit Rabah , De Alba Alvarez Ricardo , Hale Colin
Published: July 2024

Porous sound absorbers are commonly assessed by their diffuse field sound absorption. In the test, a sample of the material, having a recommended surface area of 2.44 m by 2.74 m, is placed on the floor of a reverberation room. The average sound pressure level in the room is measured
using a reference sound source and compared to the level in an empty room. Using room acoustic theory, the diffuse field sound absorption of the sample can be determined. This sound absorption is often much higher than the normal incidence sound absorption due to diffraction effects especially
at lower frequencies. In this research, a hybrid simulation method is used to determine the diffuse field sound absorption from the Biot properties of the sound absorber. Statistical energy analysis is used to model the room and finite element analysis is used to simulate the material sample.
Results from simulation are compared against measurement and agreement is acceptable.
Measuring in-situ air handling unit sound power levels for use in predicting interior sound pressure levels from replacement units
Authors: Jenkins Adam
Published: July 2024

We were faced with the need to develop a noise analysis for replacement rooftop units at a university academic building. With uncertainty about the accuracy of as-built documentation for some of the distribution ductwork and existing duct silencer performance, there was concern that
a traditional hand calculation of sound levels from the new rooftop air handling units may not be a reliable method of evaluation. We developed a test method to document in-situ sound power levels from the existing units and resulting sound pressure levels in interior spaces using a reference
sound source. These data were then used to predict interior sound pressure levels from the new units. This paper presents the test method, results, and lessons learned.
Selecting Measurement Locations for Inverse Pellicular Modes Analysis
Authors: Yan Xin , Herrin David W. , Ghaisas Nikhil
Published: July 2024

Inverse pellicular mode analysis is an approach to reconstruct an acoustic source from measurements in the sound field. After a source is reconstructed, the simulation can be used to predict the sound pressure level at some distance from the source. The method is especially useful for
considering acoustic treatments such as partial enclosures and barriers. Pellicular modes are generated by assuming a thin acoustic layer around the source boundary and determining the acoustic modes. These acoustic modes are then used as structural modes and serve as basis functions for the
inverse calculation. However, the quality of the reconstruction depends greatly on the selection of measurement locations. In this research, inverse pellicular mode analysis is used to reconstruct the normal boundary velocity on a small generator set. Different measurement set locations are
considered and sound pressure levels in the field are calculated and compared to direct measurement to assess the quality of the reconstructed source. The reconstructed source is then utilized to predict the insertion loss of a partial enclosure.
Transfer learning with cross-domain adaptation of vibro-acoustic signals for electric motor mechanical fault detection and diagnosis.
Authors: Ippili Srinivasa Rao , Russell Matthew , Wang Peng , Herrin David W.
Published: July 2024

Contact-based vibration measurement techniques involving accelerometers are typically utilized for machine health monitoring and manufacturing end-of-line quality control. Acoustic signals, encompassing sound pressure and particle velocity, carry crucial information about the operational
status of underlying equipment and can be utilized for detecting various machine faults. Utilizing one-dimensional Convolution Neural Networks (1D-CNN) based on deep learning for processing raw acoustic time signals has proven to be a valuable approach in detecting machinery faults, offering
an effective alternative to using traditional accelerometer signals. However, the success of deep learning methods is heavily dependent on the quantity and availability of data for robust network training. When transitioning to new non-contact type sensor technology, manufacturers may face
challenges due to insufficient data for training deep learning models. In such cases, leveraging existing historical accelerometer-based data becomes crucial. Transfer learning emerges as a promising solution, allowing deep learning models trained on a source domain (SD) to be applied to a
separate but related target domain (TD). This paper hence introduces a domain adaptation methodology by implementing transfer learning, where the SD 1D-CNN network is trained on accelerometer signals, then the trained model weights are transferred to the TD 1D-CNN network that can process
acoustic signals.
Active noise control without tap length selection: a model order weighting method
Authors: Zhuang Yongjie , Mittal Manan , Fernando Rashen , Corey Ryan M. , Singer Andrew C.
Published: July 2024

Conventional active noise control systems typically rely on fixed tap lengths in control filters. Determining an appropriate tap length is challenging, even within a straightforward time-invariant environment. This challenge is exacerbated when essential system responses, such as primary
noise characteristics or primary path responses, remain partially unknown and necessitate the use of an adaptive filter. A trade-off emerges between convergence rate and steady-state performance when selecting a fixed tap length in adaptive filters. In time-varying environments, the optimal
tap length may even dynamically shift over time. Thus, prior attempts have been made to introduce variable tap length algorithms to dynamically adapt tap length in real time. However, the performance of variable tap length algorithms can be sensitive to the choice of additional parameters
and noise level. This paper exploits a model order weighting approach by combining the outputs of filters of different tap lengths based on their predicted noise control performance. This proposed method demands minimal additional prior information compared to the variable tap length methods.
The noise control performance, as demonstrated by specific examples of active noise control, is presented and analyzed.
Extremely low-vibration experiments with resolutions nanometer range supported on air tables may also require a low-noise environment
Authors: Gendreau Michael , Amick Hal
Published: July 2024

The paper reports key results from an extensive diagnostic study examining a room's vibration and acoustic noise environments and their correlation to measurement noise. Vibrations of unknown origin were contaminating research being performed on highly vibration-sensitive apparatus
in the basement of a recently completed engineering building. The research involved extensive single‐molecule microscopy requiring resolutions down to 1 nm carried out on an optical table supported on pneumatic legs. Researchers reported that the experimental noise was reported to be
of random amplitude less than 40 nm. The problem did not appear to correlate with obvious building or personnel activities. The design vibration and noise criteria for the new space had been VC-E and NC-40, respectively. At the time of the study, the ambient floor vibrations were several classes
better; however, the acoustic environment was slightly worse. FRF correlation was calculated between combinations of the tabletop and floor vibrations and airborne sound. The best correlation was between tabletop vibration and airborne sound. The supply air was a significant part of the problem,
but the ceiling offered very little attenuation from above. Some of the sound was being generated above the ceiling by HVAC components other than the supply air.
Underwater sound from rotary oscillator and pile driving construction activities - I-205 Bridge over the Willamette River - I-205 Abernethy Bridge, Oregon
Authors: Reyff James , Ambaskar Adwait
Published: July 2024

The Oregon Department of Transportation (ODOT) is conducting construction work in the Willamette River that involved the installation of piles through the water. There is a potential for impacts to wildlife, primarily fish, due to high noise levels. The project added piers to the existing
bridge that consist of 12-foot diameter pile casings and drilled shafts. These casings are installed through rotary-oscillation drilled shafts that extended well below the water. These piles extend 200 feet below the river bottom. A large rotary oscillator was required to install the casings,
which was supported on temporary platforms constructed in water. The platforms were supported by hollow 36-inch diameter steel piles. Underwater sounds from rotary oscillators have not been measured extensively in the past. This paper describes the underwater sound levels and characteristics
of drilling large diameter casings deep through the substrate using the rotary oscillator. Measurements were also conducted for impact pile driving sounds from installation of the 36-inch diameter piles. The sound measurements evaluated the effectiveness of air bubble curtains meant to reduce
sound from impact pile driving and meet permit requirements to minimize exposure of fish to harmful sound levels.
Development of a recommended practice for evaluating rumble strip noise and vibration performance
Authors: Janello Carrie J. , Donavan Paul
Published: July 2024

As part of the NCHRP 15-68 project "Effective Low-Noise Rumble Strips" project, a recommended measurement program was developed for evaluating the noise and vibration performance of rumble strip designs. Two rumble strip designs located in Northern California, which included
cylindrical indentations ground into the pavement at regular intervals and a continuous sinusoidal profile, were used to assess the input to a vehicle operator and the resultant exterior noise when the vehicle departed from the travel lane. Measurements were conducted on and off shoulder rumble
strips at 60 and 45 mph with eight light vehicles ranging from small compact passenger cars to large sport utility vehicles. Six triaxial vibration measurements and six microphone locations were evaluated on the interior of the vehicle, and from these measurements, one primary and one (optional)
secondary location for noise and vibration were selected for the recommended procedure. Vehicle pass-by measurements were also made following the procedures of AASHTO TP 98 Statistical Isolated Pass-By Method. While not required, on-board sound intensity (OBSI) testing is recommended to establish
the off-strips pavement level. The recommended procedure is intended to be used by transportation agencies and other practitioners to assure comparable results when evaluating existing and alternative rumble strip designs.
Effective low noise rumble strip design and performance
Authors: Janello Carrie J. , Donavan Paul
Published: July 2024

The purpose of the NCHRP 15-68 Effective Low Noise Rumble Strips project was to develop and recommend a rumble strip design capable of minimizing the exterior noise that can impact residences along a roadway while producing sufficient noise and vibration inside the vehicle to alert
the operator of lane departure. A review of the previous research indicated that this could best be accomplished with a rumble strip of a sinusoidal profile. Twenty sinusoidal test sites were installed in Washington State, varying the wavelength from 12 to 24 inches, the peak-to-peak amplitude
from 5/16 to 1/2 inch, and the recess from 0 to 1/8 inch. Each of the test sites were evaluated using the recommended test procedure developed during Phase I of the NCHRP project, which included a primary interior noise measurement, a primary interior vibration measurement, and an exterior
pass-by measurement. Based on the accepted interior noise and vibration standard of 10 dB or more difference on and off the strips and the design goal used in this research of 5 dB or less at the pass-by location, the recommended rumble strip design is a sinusoidal profile with a 15-inch wavelength,
a 7/16- to 1/2-inch peak-to-peak amplitude, and a 0-inch recess.
Streamlined process for determining noise mitigation requirements for new development projects
Authors: Burge Paul L. , Moore Hunter
Published: July 2024

Requirements for assessing potential noise impacts and establishing noise mitigation requirements for new development project can vary significantly from state to state, and even from one municipality to the next. This paper presents a streamlined approach to simplify that process.
The process starts with a general assessment of the future project's significant noise sources and the noise-sensitivity of the surrounding area. This results in a determination of whether the proposed project would be considered a low, medium, or high noise impact project. For low noise impact
projects little or no additional noise analysis would be required for approval. For a medium noise impact project, a streamlined process is presented to quickly identify noise sources to be mitigated and preferred options for mitigation elements. For high noise impacts projects, the developer
is urged to hire a noise control professional. In each case, an appropriate level of documentation is recommended to present to the overseeing agency for review and approval.
Noise ordinances: The key to Environmental, Social and Governance (ESG) issues surrounding datacenters
Authors: Koukounian Viken , Downey Matt
Published: July 2024

The declaration of Noise Control Act of 1972 was a historic moment, whereby the Environmental Protection Agency (EPA) of the United States appropriately recognized and acted toward protecting the American population's health and welfare from the dangers of noise emission. And while
this policy served as the Gold Standard for the creation of noise policies around the world, the decision to transfer the responsibility of regulating noise to state and local levels of government is one that has had a negative impact on the acoustical industry in the United States. This paper
outlines instances where defined noise ordinances would have had protected vulnerable populations (in contiguous areas), as well as the parties affiliated with datacenters. The document also outlines methodological policies, guidance for adoption or updating of noise ordinances for Authorities
Having Jurisdiction (AHJ), examples of mission-critical systems contributing to noise emission and the most effective solutions available to achieve compliance.
Construction and validation of computational techniques as part of a holistic approach to complex engineering design
Authors: Okhovatian Sogand , Koukounian Viken
Published: July 2024

As a full-service provider of bespoke solutions to environmental noise problems, there is a need to have a precise understanding of the performance of our engineered products and complex assemblies. More specifically, there are risks, as well as limitations, to relying solely on a single
scientific method-e.g., empirical, computational, numerical or analytical. In the following paper, we describe the validation process of sophisticated computational software-a suite of Siemens software-to bolster our risk assessment practices. Although computational tools generally require
extensive 'calibration,' our interest in pursuing the software is to model diverse constraints and environmental conditions of projects, which cannot be 'simply' assessed using empirical, numerical and analytical tools. Herein are presented examples of projects utilizing our holistic approach
to assuring the performance of our engineering solutions. More specifically, we employ aero-vibro-acoustical simulations to model the aero-vibro-acoustical performance (e.g., airflow and pressure drop, dynamic insertion loss) of our industrial acoustic silencers (and similar complex assemblies).
Data Center Air-cooled Chiller Broadband and Tonal Noise Control
Authors: Wallace Brandon , Burley Dan , Kollevoll Steffan L. , Smith Steven L.
Published: July 2024

Data centers require vast amounts of cooling using large farms of air-cooled chillers as the primary equipment of choice. The amount and nature of noise generated by these chiller farms to the surrounding area can create complaints and the noise control solutions require an understanding
and knowledge of both broadband and tonal noise. The dominant noise sources on air-cooled chillers are compressors and condenser fans, each of which produce both broadband and tonal noise spectrums. Therefore, noise control solutions should address both the broadband and tonal aspects of the
source. A common noise control solution for chillers serving data centers is a sound barrier wall and while effective at providing overall broadband noise control, does little in targeting tonal issues. However, a sound barrier wall can be supplemented to address these tonal issues by applying
source treatments to the chiller, such as a sound cover treatment for the compressors and associated refrigerant piping and sound stacks and intakes for the condenser fans. In addition, barrier walls an create a "pit" application impeding chiller condenser fan discharge air resulting
in recirulation and nuisance trips. Using a sound stack source treatment with a barrier wall can help mitigate this issue while providing attenuation.
Aviation Noise Review
Authors: Farmer Kenley
Published: July 2024

The U.S. airlines have long understood that if we are to remain a critical engine of prosperity and progress, we must proactively address the environmental impacts associated with aviation, including noise. Through enduring research and development and public-private partnership programs
bringing together government, industry, and academic institutions, significant technological advances have led to the development of much quieter aircraft. U.S. airlines have worked in cooperation with the FAA and other aviation stakeholders for decades to reduce aircraft noise, achieving
tremendous results. This paper will include a review of the airline response to FAA's recent noise policy review, including a review of the evolution of noise standards for aircraft, which has resulted in a lower number of people exposed to significant levels of aircraft noise, even while
the number of passenger enplanements continues to grow. Despite this progress, aircraft noise remains an important issue for many communities and an array of aircraft noise management regulations and procedures must be pursued to address noise concerns.
Low frequency sound limits for live amplified outdoor music
Authors: Lodico Dana , Haac Ryan
Published: July 2024

The Rock Sports Complex (ROC) in Franklin, Wisconsin contains a number of outdoor recreational facilities, including a minor league baseball stadium, a drive-in movie theater, an outdoor concert venue, practice fields, and a ski hill. Residents adjacent to and up to one and a half miles
from the ROC have reported disturbances from sound generated by the facility both inside and outside of their homes. A sound study was undertaken to understand these concerns and to make recommendations for thresholds to be used to balance the desire for facility events with the concerns of
nearby residents and businesses. One focus of this effort was the quantification of low frequency (~63 Hz) music from the outdoor concert venue at surrounding residences. This paper discusses the low frequencies generated by the facility, as measured in the surrounding communities, and how
they compare to noise ordinances for other US municipalities.
Modeling a low-frequency sound absorber consisting of a granular activated carbon stack backed by a poro-elastic layer
Authors: Song Guochenhao , Mo Zhuang , Shi Tongyang , Bolton J. Stuart
Published: July 2024

High surface area particles, like granular activated carbon (GAC), have shown advantages in absorbing low-frequency sounds by themselves and when combined with other treatments. In this article, a novel sound absorption treatment consisting of a high surface area particle stack supported
by a soft, porous layer is described. It was first experimentally observed from impedance tube measurements that the low-frequency absorption performance of GAC stacks can be significantly enhanced by inserting a melamine foam between the stack and a rigid backing. To analytically model this
type of sound absorbing treatment, the interfaces between particle stacks and other materials were characterized. Further, a 1-D layered transfer-matrix approach and a 2-D axi-symmetric finite-difference approach were implemented to predict the measured absorption spectra. Because of the constraint
of the stack at the impedance tube wall, the 2-D axi-symmetric model leads to more accurate absorption spectrum predictions, particularly at low frequencies. However, the difference between the two model predictions becomes negligible when applied to large-area treatments. Thus, the simpler
and faster 1-D theory can be valuable for optimizing large-area sound packages. In addition, by combining both granular and porous materials, it may be possible to design sound-absorbing metamaterials that perform well at low frequencies.
Low-frequency HVAC 'rumble' in a high-end condominium
Authors: Marshall Steven E.
Published: July 2024

Sound and vibration measurements were conducted at a high-end condominium located in downtown Washington DC.  Data was collected within the client’s residence unit and on the building’s roof. The objective for the measurements was to identify and characterize the sound
within the unit for which the resident had complained. The source of the sound in the bedroom was identified from vibration on a wall adjacent to an HVAC vertical duct. The sound and vibration were found to originate at a roof-mounted fan integral to the HVAC air distribution system. The character
of the sound was modulating, low-frequency ‘rumble’. Further investigation on the roof, however, revealed the building’s structure to be adequately isolated from vibration due to the fan and motor. Rather, the sound was generated by the interaction of the fan’s aerodynamics
and the acoustical properties of the vertical duct. The amplitude of the acoustic field in the duct was sufficient to excite vibration of the duct’s enclosing walls. Instead of modifying the structural geometry of the vertical duct, the most efficient ‘fix’ to attenuate duct
rumble was by installing a silencer in the horizontal duct between the exhaust fan and the vertical duct.
Comparison of modelling methodologies for large porous absorbers hanging in a volume
Authors: Burns Tom
Published: July 2024

Porous material simulation methodologies are well established. However, most methods, like the Transfer-Matrix Method (TMM) make the assumption that there is a source side and a receiver side. In practice, this works for the majority of industrial noise control treatments. For architectural
applications, this is not always the case. Hanging absorbers and curtains are common materials that add absorption to a space, but do not have a boundary condition at a wall or a well-defined source and receiver side. To evaluate the validity of existing simulation methods for this condition,
a reverb room test was simulated with a large cube of melamine foam inside the volume. The effective absorption of the cube in the space was then calculated using various simulation methodologies, and compared to results from a measured reverb room absorption test.
Down-the-hole drilling construction acoustic research
Authors: Reyff James , Ambaskar Adwait
Published: July 2024

nd The Alaska Department of Transportation and Public Faculties (DOT&PF) is conducting research to characterize underwater sounds from down-the-hole (DTH) drilling activities. This method of drilling is commonly used to drill holes through hard or rock substrates to support piles
or tensions anchors for piles. A pneumatic DTH hammer is driven by pressured air coming from an air compressor that provides the energy to power the percussion piston that hits the drill bit with a specific impact frequency and energy to break the rock and advanced the hole. This activity
produces continuous and impulsive sounds that affect marine mammals. Pile installation in marine environments typically uses vibratory drivers and/or impact pile driving. Underwater sounds from these activities have been well documented in publications, for example, there are compendiums prepared
by Caltrans, and the U.S. Navy, along with many project-specific compliance reports submitted to resource agencies. However, there is limited acoustical data available for DTH activities, as the first published measurements were only made recently. The National Marine Fisheries Services (NMFS)
recognizes the acoustical issues with DTH noise and is encouraging the collection and dissemination of additional sound data. This paper describes the research conducted and available DTH acoustic data.
Study on tone-to-noise ratio calculation method for tones with frequency and amplitude variation
Authors: Xu Yanchu
Published: July 2024

This paper is to present a method on improving consistency and accuracy of Tone-to-Noise Ratio (TNR) calculation for varying frequency tones in reporting prominent discrete tone according to ECMA-418-1. For given sound pressure spectrum, existing TNR calculation methods require suspect
tones to be selected by the analyst, who must also determine the width of the tone, that could introduce significant uncertainty and variation between different analysts. Moreover, tones associated with unstable frequency could cause even more uncertainty in determining tone frequency band.
In this study, an approach is proposed to determine the existence of discrete tone, define the tone frequency band, and lastly calculate TNR such that different analysts will be able to obtain consistent and more accurate TNR value. To validate the approach, several different noise spectra
were used as mask noise, and thousands of numerically generated tones, with randomly varying frequencies and amplitudes, were modulated to the mask noise to generate synthesized waveform for TNR calculation. These randomly generated synthesized waveform were subjectively evaluated and confirmed
that prominent discrete tone criteria are still applicable to tones with varying frequencies and amplitudes. The results show that proposed approach can significantly improve TNR calculation accuracy while ensure consistency between different analysts.