bluuebunny/crossref_metadata_2025 huggingface dataset:
Wake Stone Quarry Expansion: An acoustical and legal saga win
Authors: Thalheimer Erich Steffen , Poling Jacob
Published: July 2024

The Wake Stone Quarry in Cary, North Carolina, has been in operation for over 50 years excavating aggregate rock and gravel for roadways and concrete mixtures. Their initial open mining pit was nearly exhausted, so they sought permission from the State to begin a second pit on their
existing property. Unfortunately, opposition came from the heavily politically connected non-profit Umstead State Park that abuts the quarry's property. To Wake Stone's dismay, their application was arbitrarily and capriciously denied. What should have been a simple and straight-forward permit
application turned into four years of intense acoustical and environmental studies eventually ending up in court. The main point of contention was noise potentially impacting the adjacent park, which was complicated all the more by the applicable state law being worded only qualitatively as
"the applicant will not have a significantly adverse effect on the purposes of a publicly owned park, forest or recreation area". The stakes were very high; estimated at a future value of $500 million for Wake Stone. With WSP's assistance, including providing acoustical expert
witness testimony in a lengthy two-week trial, Wake Stone eventually won their lawsuit and overturned the State's permit denial.
A collaborative approach to low-frequency noise mitigation
Authors: Carballeira Andrew , Downey Matt , Keelty Dave , Kaliski Kenneth , Single Richard , Tocci Gregory
Published: July 2024

This case study examines efforts to study and mitigate low-frequency noise produced by boilers serving a large hospital. The work was completed by a collaborative group of citizens, hospital staff, acoustical consultants, and noise control solutions providers. While none of the noise
controls are novel from an engineering perspective, the criteria, experimental methods, and consensus strategies used for this project could serve as a model for similar community challenges.
Tutorial on Signal Processing Impacts of ICP(r) Accelerometer Limit Violations
Authors: Hambric Stephen , Taggart Andrew
Published: July 2024

Accelerometers with embedded Integrated Circuit Piezoelectric (ICP) circuitry are complex electro-mechanical systems. The mechanical and electrical components are designed to provide wide ranges of linear response (voltage induced by a given acceleration) over amplitude and time (frequency).
However, every sensor has limits, and exceeding those permissible limits can lead to attenuated, amplified, and even clipped signals. Sometimes, signals are unmeasurable due to 'noise floors.' This tutorial explains: piezoelectric sensor operating principles; how ICP-powered accelerometers
measure fluctuating vibrations; the lower and upper limits of linear response and what causes them, both in amplitude and frequency; and the effects of violating those limits on response frequency spectra using signal processing theory and examples.
The 2023 Technology for a Quieter America Workshop: occupational noise exposure - risks and controls
Authors: Thompson Jim
Published: July 2024

The 2023 Technology for a Quieter America (TQA) Workshop was held October 24-25, 2023, in Washington DC. The topic of this workshop was Occupational Noise Exposure - Risks and Controls. This was the 13th TQA workshop covering a wide range of topics related to noise control. With 22
million American workers overexposed in the workplace every day, this is an important topic. This workshop brought together a diverse group of people with differing perspectives on this problem. Included in the discussion were audiologists, nurses, medical researchers, physicians, engineers,
industrial hygienists, and faculty working on this topic. This workshop demonstrated that there is practically no industry in which workers are safe from overexposure and US employers depend to much on hearing protection devices to protect workers.
The European Environmental Noise Directive in Germany
Authors: Hintzsche Matthias
Published: July 2024

With the Environmental Noise Directive, the member states of the European Union have a common approach to mapping and reducing environmental noise. Noise exposure is determined in agglomerations and around major transport infrastructures. Noise action plans specify measures to reduce
noise. With the fourth round in 2022, the directive was significantly developed. For the first time, common European assessment methods were used for noise mapping of road, rail and air traffic, as well as industrial facilities. In addition, the effects of noise exposure were determined on
the basis of WHO dose-response curves for noise annoyance, sleep disturbance and ischemic heart disease. The results of the noise exposure measurements are also to provide the basis for political decisions at the European level on the reduction of limit values or financial support programs.
To allow better interpretation and comparison of the data, the technical requirements for data reporting by the Member States to the European Commission have been specified. The paper reports on the experience in Germany with Noise Mapping 2022 and describes challenges and further planning.
Sound absorption uncertainty in small reverberation chambers
Authors: Moritz Charles , Biboud Julien
Published: July 2024

Manufacturers in the mobility industry typically measure and specify the sound absorption coefficient of materials using a small reverberation chamber according to SAE J2883. These chambers have a 6 to 25 cubic meter volume, use a 1.0 meter x 1.2 meter sample size and report sound absorption
in the one-third octave bands from about 400 Hz to 10,000 Hz. This is in contrast to a full-size chamber built to satisfy the requirements of ASTM C423 or ISO 354, which have about a 200 cubic meter volume, use a 2.4 x 2.7 or 3.2 x 3.2 square meter sample size and report sound absorption in
one-third octave bands from 100 to 5,000 Hz. Although the room and sample size dimensions scale, many of the factors that contribute to uncertainty in the measurement do not scale. These include relative humidity, temperature, and other physical measurements and if the same instrumentation
is used, microphone calibration and measurement uncertainty in the higher frequency range. This paper examines the potential measurement uncertainty in these chambers over the 400 to 10,000 Hz frequency range and compares this to past uncertainty analyses of full-size chambers over a similar
frequency range.
Application of Bayesian Decision Analysis to Estimate Occupational Noise Levels from Limited Exposure Data
Authors: Massawe Ephraim A. , Fayed Ahmad
Published: July 2024

In recent years, Bayesian statistical modeling approaches have emerged as valuable tools in Industrial Hygiene (IH), particularly in situations with limited exposure data. This paper delves into the application of Bayesian Statistical Models, specifically Bayesian Decision Analysis
(BDA), to analyze occupational noise exposure data within two Similar Exposure Groups (SEGs) of groundskeeping workers, addressing the pervasive issue of high noise levels exceeding 85 dBA. The primary aim is to estimate exposure levels based on the location of the exposure profiles for the
SEGs within the AIHA® Exposure Control Categories (ECCs) 0-4, later modified and expanded to AIHA-ECC 0-5. This study employs BDA to estimate noise exposures among groundskeepers, emphasizing the scarcity of literature on BDA in noise exposure rating. Groundskeepers, facing potential
risk of hearing impairment due to prolonged exposure, constitute a crucial and critical demographic, with nearly one million individuals in the United States alone. Noise data from the two SEGs was analyzed by using the Exposure Assessment Strategies Committee—EASC- AIHA® IHData
Analyst for BDA modeling,  complemented with the AIHA IHSTAT™  for certainty rating. The resulting posterior graphs were utilized to categorize exposure profiles into respective AIHA ECCs relative to noise OEL.  These findings provide valuable insights, indicating a posterior
probability of  approximately 43.5% and 56.5% with 95% confidence that noise exposure levels fall within AIHA ECC 3 and AIHA ECC 4, respectively.  However, while the 95% percentile decision statistics suggest exposure values lower than the OEL, the Upper Tolerance Limit (UTL) significantly
surpass the OEL indicating low certainty regarding these exposure values for employees. Notably, the UTLs suggest that the SEGs are experiencing noise levels above the legally required 90 dBA for more than 5% of the time, which is an unacceptable scenario.  Recommendations include implementing
protective strategies such as regular training, surveillance, and monitoring, alongside engineering control strategies and mandatory use of personal protective equipment. These results underscore the critical need for refining judgments about noise exposures based on variability within and
between employees, suggesting the use of additional statistical tools such as ANOVA (single-multivariate), MATLAB, and Python.
Localization and Sound Power Estimation of Sound Sources in Industrial Plants using the Sound Field Scanning Method
Authors: Rittenschober Thomas , Karrer Rafael , Decloux Antoine
Published: July 2024

Reducing sound emissions from industrial plants requires an initial step of localizing key contributing sources. Acoustic cameras are pivotal for quickly identifying these sources, yet challenges persist in low-frequency source localization and presenting results for effective impact
assessment. This contribution introduces the Sound Field Scanning technology, utilizing a rotating linear microphone array covering a measurement surface with diameter of 2.5 meters for low-frequency source localization from 125Hz. The underlying sound imaging method compensates for Doppler
distortions in the moving microphone signals and evaluates coherence spectra with a non-moving reference microphone to compute an acoustic image. For analysis, a method quantifying sound power contributions from specific regions in the optical image is presented. Comparing sound power metrics
of the full optical field of view with metrics of regions of interest enables users to quickly rank source contributions and assess the impact of reducing these contributions on total sound power. In complex scenarios, preliminary investigations can be streamlined with a few measurements from
diverse angles, expediting the problem-solving process with confidence. The method is exemplified through the analysis of sound emissions from a production plant.
Case study of automotive NVH topics induced by HVAC systems integration
Authors: Bennouna Saad
Published: July 2024

Within the automotive market, HVAC systems are of critical importance in ensuring passengers' thermal comfort inside the car cabin as well as complying with regulatory defogging functions. These systems involve various components such as blowers, thermal exchangers, actuators... over
a wide range of well-known technologies and also innovations on newly introduced designs and products. Currently, within the established electrification trend worldwide, HVAC systems became one of the most important embedded systems, possibly inducing major contributions of noise and vibration.
These NVH topics can emerge through various transfer paths inside the car cabin causing significant discomfort to passengers. During development and production stages, the NVH behavior at component level is mastered by both suppliers and OEMS according to internal standards and specifications.
However, implementation into the complete vehicle can induce a specific NVH behavior unrelated to the compliance status at component level. Integration impact cases are highly reinforced within electrification trends as they involve more and more design changes with less technical background.
Through a practical case study, this paper focuses on the NVH behavior induced by the integration of HVAC systems in the US market. Transfer paths analysis and solutions are investigated to improve the NVH behavior and set the product intrinsic limits giving the targeted vehicle.
Understanding How Filters Affect Data
Authors: Hiatt John
Published: July 2024

There are many filters in digital data acquisition and analysis. These filters have both positive and negative effects on the data.  While the positive effects (like removing signal in specified frequency bands) are obvious.  The negative effects (like signal delays) may not
be so obvious.  This presentation will discuss in detail the negative effects on the data and how these effects can be mitigated.  We will cover the Finite Impulse Response (FIR) and Infinite Impulse Response (IIR) filters.
The two-cavity method for characterizing acoustical materials-an interlaboratory study
Authors: Brown Martha , Ciletti Anthony Vincent , Sharma Bhisham
Published: July 2024

The study focuses on understanding the sound absorption and transmission characteristics of porous acoustical materials, which are determined by two key parameters independent of material thickness: characteristic impedance and propagation constant. These parameters can be characterized
by testing a porous sample concept in a normal incidence impedance tube using either the two-thickness or the two-cavity method. In the two-thickness method, two samples of varying thicknesses are required. In contrast, the two-cavity method requires testing one sample at two air cavity depths.
This method is particularly advantageous for materials that are costly or challenging to fabricate. This interlaboratory study evaluates the variability of characteristic properties determined using the two-cavity method. Porous acoustical materials were additively manufactured and tested
in the Liner Technology Facility at NASA Langley Research Center and the Mechanics, Acoustics and Dynamics Lab (MADLab) at Michigan Technological University. The characteristic properties, derived from various cavity depth combinations, were used to predict the sound absorption curves of the
sample with a rigid backing. These predictions were then compared with actual experimental absorption curves. The findings indicate that both the combinations of cavity depths and the sample's static airflow resistivity significantly influence the accuracy of the deduced properties.
A year of background sound measurements in suburbia
Authors: Bahtiarian Michael
Published: July 2024

An internal research project was undertaken to measure the background sound levels at one location with the same equipment for a full year. A suitable location was identified to allow the equipment to stay in the same place and available to refresh data memory cards and battery power.
The sound monitoring was done from October 2020 through November of 2021. The site selected was a typical suburban residential property near a secondary road, but far from other influencing sources of sound like highways and industry. The data set is over 9,000 hourly samples of A-weighted
sound levels. For each hour the L99, L90, L50, L10, L01 and LEQ were recorded and evaluated for this study. This paper addresses the compilation of the year worth of A-weighted sound levels. The data set also includes one-third octave band sound pressure levels, but those data have not been
considered in this evaluation. The noted sound metrics have been evaluated by month, day of the week and hour. The paper also evaluates the selection of the lowest background sound level that is used in many noise ordinances, including the author's home state of Massachusetts.
Sampling effects on background noise corrections
Authors: Oppenheimer Charles
Published: July 2024

Background noise corrections are used to estimate true source levels from measured source levels. Use of a background correction involves determining the background noise from measured samples. Previous work explored the effect of sampling on the statistical background noise correction
through the steadiness parameter. In this paper the effect of sampling on the statistical and legacy background noise corrections through the steadiness and source-background level difference parameters is investigated. Samples of background noise are drawn from a chi-square distribution,
which has been shown to describe background noise arising from multi-path or multi-mode processes. Background mean and variance are determined from a specified number of background noise samples, and statistical distributions and confidence bands are formed. The distributions and confidence
bands of the statistical and legacy background noise corrections are compared and are used to identify parameter ranges that promote accuracy of source levels obtained with background noise corrections. Specific limits on these parameters are recommended for the statistical background noise
correction. The benefits and advantages of the statistical background noise correction are identified, and a path towards standardizing the statistical background noise correction is proposed.
Measurement and documentation recommendations for reporting footfall floor vibration performance in mass timber buildings
Authors: Brush Ethan
Published: July 2024

Construction methods utilizing mass timber are increasingly offering more sustainable and eco-friendly solutions for vibration sensitive buildings that have traditionally used only concrete or concrete and steel materials. Regardless of the building material, it is important to consider
vibration serviceability with respect to occupants or sensitive equipment as part of the design process. Several references are now available to help with the footfall vibration design of mass timber floors. These references borrow heavily from established methods outlined in American and
European design guides for steel and concrete construction. What cannot be borrowed from these guides is the wealth of empirical validation data that has been obtained from measurements in steel buildings. As more mass timber buildings are built, it will benefit the community to have floor
vibration performance measurements to further inform and validate prediction and design methods. This paper discusses measurement methods and documentation items to report floor vibration performance in existing mass timber buildings. The consistent reporting of the collected empirical data
will help standardize future design prediction methods and validations with these structures.
Forecasting community response to low-frequency noise
Authors: Nelson David
Published: July 2024

The most common approach to managing environmental noise is by reference to A-weighted sound levels deemed appropriate for the community. These criteria are usually derived from transportation noise studies for which the relative proportion of low-frequency noise is implicit. Very different
community reactions can arise when source spectra don't represent those studied. Responses diverge even further when the listeners' context also differs from that originally studied. This is nowhere more evident than in the case of large industrial equipment (such as power plants and gas compressor
stations) sited in rural areas, due in large part to strong Low-Frequency Noise (LFN). Guidance for forecasting community reaction to LFN is scattered throughout the literature as individual studies employing a diverse assortment of approaches and noise descriptors. The purpose of the present
paper is to demonstrate a straightforward, comprehensive, and unified forecasting approach suitable for inclusion in ANSI S12.9 Part 4 "Noise Assessment and Prediction of Long-Term Community Response", similar in many respects to the method recently deleted from this standard (2005
Annex D).
On the modeling of urban air mobility vehicle takeoff and landing operations in the FAA Aviation Environmental Design Tool
Authors: Letica Stefan , Rizzi Stephen
Published: July 2024

Urban air mobility (UAM) vehicles are anticipated to operate in close proximity to the public. A possible barrier to the introduction of UAM vehicles as a transit solution is their community noise impact, particularly around vertiports. The Federal Aviation Administration Aviation Environmental
Design Tool (AEDT) is the mandated tool to assess aircraft noise and other environmental impacts due to federal actions at civilian airports, vertiports, or in U.S. airspace for commercial flight operations. However, AEDT was designed to model fixed-wing aircraft and conventional helicopter
operations, not UAM vehicles. Prior work by the authors showed significant differences in noise contours of UAM departures and approaches when modeling operations as fixed-wing and helicopter types in AEDT. This paper identifies the sources of those differences. Additionally, a NASA time-marching
simulation tool is used to generate noise exposure data for equivalent operations to help identify differences associated with the integrated noise model implemented in AEDT and offer possible changes to assess UAM community noise impact more consistently with simulation-based modeling.
Modeling noise from large-scale data center equipment
Authors: Buck Adam
Published: July 2024

Data centers present unique noise modeling challenges due to the scale of equipment needed to meet cooling and backup power demands. Three-dimensional environmental noise modeling software that is based on ISO 9613-2 "Attenuation of sound during propagation outdoors" offers
a range of modeling techniques. While more detailed modeling techniques may offer more accuracy in the near field, they also increase model calculation run times. Additionally, manufacturer sound emissions data often more closely align with simplified modeling techniques. This evaluation reviews
common data center noise sources, reviews the range of manufacturer noise emissions data typically available for such sources, and compares noise modeling techniques with reference to on-site observations.
A comparison of impulsive noise metrics
Authors: Oppenheimer Charles , Way Evelyn
Published: July 2024

Impulsive sounds are transient acoustic events that can draw undesirable attention because of their abrupt nature, for example sounds produced by weights dropping onto floors in buildings. A metric that represents human experience of these sounds can guide efforts to mitigate them.
This paper investigates metrics developed for impulsive sounds generated by weight or ball drops and by IT equipment. The metric for IT equipment is an impulsiveness metric formulated with psychoacoustic bands and loudness descriptions. The metric for weight or ball drops is the fast time-weighted
sound pressure level implemented with various filtering schemes. The ability of the metrics in predicting subjective human experience of IT equipment transients is compared. Metric values for sounds generated by ball drops onto various floor assemblies on a concrete slab are compared.
Electric Motor Noise Variation Study Due to Air Gap Effect in Electric Vehicles
Authors: He Song , Curtis Jeffrey , Bahuguna Saurabh , Jensen William , Maddipati Seshagiri Rao , GSJ Gautam
Published: July 2024

Motor whine is a crucial factor in the design of electric motors for electric vehicles (EVs). Predicting noise in a virtual environment is challenging due to the many possible variations during sample testing. The air gap between the stator and rotor in each sample is a significant
contributor to radiated noise variation in the electric drive unit (DU). A baseline is first established for radiated noise prediction, assuming a nominal uniform airgap distribution, using the front electric DU in General Motors' Hummer EV. This study explains how the sensitivity of critical
motor orders changes with static offset direction when the stiffness of DU is non-uniform and varies with radial direction. It also predicts the range of motor airborne noise variation due to offset orientation. Next, the effect of tilt direction on motor noise variation is studied at different
torque conditions and motor speeds. Motor noise is found to be sensitive to tilt direction and angle as the DU stiffness changes axially. Additionally, rotor dynamic offset is investigated, which generates sideband orders in addition to motor pole pass orders. A comparison study is conducted
to examine various sideband orders and their central frequency.
Analysis, Design & Installation of Vibration Isolation for Lightweight Helipads
Authors: Dias Ashwin , Rodrigues Alfredo , Saddik Freddy
Published: July 2024

This case study discusses the design and manufacturing steps for the installation of a vibration isolation solution for two lightweight helidecks installed on the rooftop of an existing medical center building. The design stage involved the analysis of the relevant information, involving
several specialties, such as Acoustics (for sources of vibration and acoustic performance requirements), Heliport Design (for the type of aircraft, MTOW, number of supports, static and dynamic loads) and Structural (for the types of connections to the existing building structure). A collaborative
effort between CDM Stravitec and the helideck supplier led the design through a progressive and iterative process where a final design that responded to the strong acoustical requirements and the complex nature of a fully functional and integrated lightweight helideck. Along the design, compromises
where made ensure that requirements are met for both acoustic and structural performance. The solution delivered was a prefabricated box, that could easily be installed on site, comprised the necessary components such as springs and uplift restraints to deal with the challenging aspects of
the isolation of lightweight helidecks. The paper also discusses the challenges and best practices encountered during the production and installation of the system.
Laboratory measurement of treadmill noise under several speeds, runners, and floor coverings
Authors: Reidling Justin
Published: July 2024

Treadmills are an important generator of noise in the retail fitness and multi-family housing environments. Field studies have demonstrated that treadmills have a low-frequency sound characteristic, and treadmill use can lead to neighboring-occupant annoyance and necessitate consideration
in building design and space planning. This work presents sound level measurements of a treadmill in operation to report sound levels and the effect of runner speed, runner cadence, and floor covering. Tests were conducted on an elevated 6-inch concrete slab in a vertical laboratory setting,
and results are in terms of measured SPL in the lower room. Runner speed and floor covering were confirmed to be relevant variables in sound levels due to treadmill noise. Spectral shapes in multiple tests were found to be similar despite presence and composition of floor covering. Results
on the effect of runner cadence are not conclusive. SPL was lower than expected due to the relatively stiff structural floor, and future testing should continue to pursue higher source levels.
Singing buildings: effects and potential causes of wind-induced noise from balcony systems
Authors: McCabe Nick , Gara Nathan , Howe Brian
Published: July 2024

Modern high-rise residential buildings are wrapped in balcony railings of a countless number of styles, shapes, and materials. This study investigates the effects and potential causes of wind-induced noise and vibration caused by balcony railings; a phenomenon that continues to gain
significance in urban environments. This study includes field measurements to quantify the extent and nature of wind-induced noise and vibration from various balcony railing designs exposed to a wide variety of meteorological conditions. A detailed examination of potential causes is also undertaken,
considering material properties, structural design, and aerodynamic characteristics. Finite element analysis is employed to model and simulate the dynamic response of several different balcony railings, providing insights into the key factors influencing noise generation. The findings of this
study offer practical insights into optimizing balcony railing designs to minimize wind-induced noise.
Sounds of the Skagit: a comprehensive noise model for a large hydroelectric project
Authors: Copenhaver Benjamin J.
Published: July 2024

The Skagit Hydroelectric Project comprises three dams and power plants in the North Cascades and transmission lines running from the plants to Seattle. HDR helped Seattle City Light complete numerous studies in support of relicensing of the Project. The sound study was charged with
evaluating noise from all project-related activities, which include noise from the powerhouses, transmission lines, dam spill events, emergency sirens, telephone alerts, helicopter flights, boat traffic, vehicle traffic, construction equipment, and even a locomotive bell rung by visitors.
Models used include Cadna-A, AEDT, and BPA's corona noise model. The sound study also included week-long measurements of existing noise at six locations during summer (peak recreation season) and spring (off-season), processed using National Park Service methods. Regular emergency siren testing
allowed the model to be validated across long distances using the noise monitoring data. This presentation will discuss the varied approaches HDR's acoustics team used to synthesize all of these aspects into one award-winning sound study - this project won INCE's 2023 Nancy Timmerman Member's
Choice Award.
Challenges in acoustical modeling of data centers
Authors: Pendyala Samuel A. , Snow Kody
Published: July 2024

Data centers are physical infrastructures that house computing machines and related hardware equipment for data storage and processing. Due to the ever-increasing trend of cloud computing and the need for secure data storage, several organizations are involved in the development of
large data center facilities. This new industry sector is seeing massive growth in recent years and municipalities and counties across the nation are welcoming the construction of data centers in their areas. Acoustical modeling for a data center can be challenging due to various factors and
this article discusses a few such challenges that were experienced during the acoustical assessments of data center operations.
Car wash noise reduction - case study
Authors: Sorenson Steve , Spencer II Robert , Morrow Anthony
Published: July 2024

A car wash is installed in one corner of a large industrial building with the exit feeding into the building interior. The building interior is largely open space with a high roof. This houses multiple activities going on at any given time including part fabrication and vehicle retrofitting.
The space available for the car wash necessitates the exit door to open during the drying cycle. The blower noise during the drying cycle with the exit door open is not loud enough to require hearing protection in the facility. The functions held within the space eventually expanded to include
meetings requiring speech communication. The noise during the drying cycle was loud enough to disrupt audibility. An ad hoc team worked to reduce noise levels sufficiently to allow all other activities to continue without noise disruption during car wash operation. This paper addresses the
diagnostic work and countermeasures put in place to achieve this goal.
Integrating multi-microphone devices and AI for noise event identification in unattended monitoring
Authors: Ejdfors Karl Henrik
Published: July 2024

This paper explores the use of multi-microphone devices and artificial intelligence (AI) for the identification of noise events in unattended noise monitoring. The system presented aids in the identification and localization of dominant sound sources using time difference of arrival
techniques. By incorporating AI technology, the system's software automates the extraction of non-relevant sounds. The algorithms enable removal of undesired components, resulting in a more accurate measurement. This article discusses the benefits and limitations associated with employing
automatic processes in noise monitoring and analysis software. Finally, a current application and prospects for future advancements in the field are presented.
An annoyance model for urban air mobility vehicle noise in the presence of a masker
Authors: Tracy Tyler , Boucher Matthew , Christian Andrew , Krishnamurthy Siddhartha , Rizzi Stephen , Begault Durand , Shepherd Kevin
Published: July 2024

Proposed Urban Air Mobility (UAM) operations offer an alternative to road and rail traffic for local and regional movement of people and goods. To allow for large-scale adoption of UAM vertical takeoff and landing (VTOL) aircraft, it is critical to predict human annoyance response to
the noise generated by these vehicles. This paper proposes a model that predicts an individual's perceived level of annoyance when presented with UAM VTOL aircraft noise in addition to a masking noise. The model predicts changes in annoyance based on subjective evaluation of detection, noticeability,
and annoyance of noise in the presence of a masker. The application of this annoyance model will influence future work for a psychoacoustic annoyance model that incorporates UAM sound quality.
Advances in elastomeric mount concepts for quasi-zero stiffness isolation
Authors: Merrifield Ava , Fredette Luke
Published: July 2024

Quasi-zero stiffness (QZS) mounts can exploit geometric nonlinearity to minimize stiffness about an operating point which isolates vibrations from a supported source or receiver. Previous research on elastomeric QZS mounts featured 3D printed prototypes but did not consider unique material
properties and fabrication artifacts that may impact the static and dynamic behavior of the mounts. Additionally, multi-axis properties and their influence on common, box-like systems supported by several mounts lacks detailed study. To overcome these limitations and improve the practicality
of elastomeric QZS mechanisms, this paper discusses nonlinear stiffness, hysteresis, and fabrication issues with elastomeric materials in this context. Multi-material mount designs that improve strength and stability are considered, and their effectiveness for QZS isolation is experimentally
evaluated. System-level dynamics are presented for a box-like load supported by QZS mounts. Comparisons between additive and cast materials in the fabrication of QZS mounts are discussed, and the mounts' dynamic stiffness amplification effect is examined for additive and molded materials.
Fault diagnosis of drivetrain systems based on vibration signals and convolutional neural networks
Authors: Aguilera Diaz Francisco , Wei Xinqi , Wang Yawen , Pickard Philip David , Tang Steven Thanh
Published: July 2024

Accurate and fast fault diagnosis can improve the reliability of drivetrain systems. The fault diagnosis model based on convolutional neural networks is tricky because the accuracy and efficiency of diagnosis depend on the neural network parameters, such as layer size and number of
layers. In this paper, we developed a data pre-processing technique to format vibrational data to be receptible to a neural network. First one will study the difference in performance by inputting a spectrogram of the vibrational data compared to the raw data itself. Second, the windowizing
technique is used and its parameters are explored to train different configurations of convolutional neural networks. Finally, the optimal neural network parameters are obtained to improve the computational efficiency while the training model has the highest accuracy.
The future of ANSI/ASA S12.2 and room noise criteria
Authors: Cudequest Brandon
Published: July 2024

A working group is evaluating the American National Standard, "Criteria for Evaluating Room Noise" (ANSI/ASA S12.2-2019). This presentation will give an overview of our progress and areas of significant proposed change. The goal is to simplify the standard body so that the
criteria reflect industry practice. Historical references and less common criteria will be relegated to annexes. Since the beginning of this standard, there has been interest in determining spectral imbalance, temporal variation, and the presence of tones. This talk will briefly mention proposals
to quantify these aspects. Feedback from the industry is welcome to minimize the challenges associated with implementing this standard.
Airborne acoustic assessment of impact-resistant fitness flooring systems
Authors: Vera Stalin
Published: July 2024

Fitness facilities in residential and mixed-used commercial buildings introduce important acoustic design challenges that must be considered in a building. Cardio activities such as running on treadmills, group classes for high intensity training, and weight training areas introduce
high levels of unwanted noise and vibration into a building structure. Isolated floor constructions are generally coordinated and implemented during design but are not practical when buildings are completed and occupied. Impact-resistant fitness flooring systems are typically explored and
installed as an alternate approach to reduce the transmission of impact noise and vibration. Non-standardized field airborne noise measurements of weight drops were conducted on an existing gym and on four possible impact-resistant fitness flooring upgrades to assess the reduction of impact
noise levels in the offices located below the gym. The measurements were also compared to the HVAC background noise levels to observe the increase above background conditions and provide a subjective evaluation. The results of the measurements show that impact-resistant fitness flooring systems
provide a noticeable reduction of impact noise, compared to standard fitness flooring systems. The results also show that impact-resistant fitness flooring systems that include specialty engineered shock pads as a base layer provide a significant reduction of impact noise levels.
Tube Dissipation estimation for the Transfer function method using Bayesian inference
Authors: Chen Ziqi , Xiang Ning
Published: July 2024

Impedance tube measurement is commonly used in material research and building acoustics to study the acoustic properties of materials. However, air dissipation caused by multiple effects affects the accuracy of measurement results. This work discusses sound dissipation due to different
effects in an impedance tube. The air layer method is used to measure the dissipation and to calibrate the tube. Accurate dissipation due to different effects is estimated by model-based Bayesian inference. The Bayesian analysis demonstrates the impact of tube dissipation on the acoustic measurements.
The estimated tube dissipation drastically improves the accuracy of regular two-mic impedance tube measurements.
Modal spectrum analysis for an imperfect beam model with random vibration
Authors: Kim Jung-Hwan
Published: July 2024

The cross-Spectral Density (SD) is a method of analyzing the relationship between randomly-input forces and their responses in the frequency domain in spectrum analysis. It is essential for analyzing antiresonant eigenfrequencies that are difficult to understand using only direct-SD.
Additionally, the mass in a beam is often analyzed in modern engineering to control the vibration characteristics of a simple beam or as a major model for error. Especially, the scalability can be expected in various fields such as nanosensors as well as macroscopic scale by studying imperfect
mass. Firstly, the correlation function and SD are defined for an arbitrary vibration input in a beam. Then, the response function is established according to a harmonic input of some unit force amplitude. Moreover, the direct- and cross-SDs for the response are calculated and mathematically
compared with both results. Further analysis is performed by comparing the variation of the SD with response position, the standard deviation (StDev) of the mean of maximum responses, and the bandwidth. The developed cross-SD of the imperfect beam extends the previously developed SD models
of the perfect beam and can provide ideas for new types of eigenfrequency analysis, vibration isolation, etc.
Characterization of multi-rotor aircraft using truss support structure
Authors: Mobley Frank Spencer , Wall Alan T. , Campbell Steven C. , Rasband Reese
Published: July 2024

Characterization of multi-rotor drone aircraft noise is vital to expanded use within the United States. To provide compatibility with current propagation and perception models, acoustic noise characterization focuses on the creation of equivalent lower hemispheres, and application of
methods developed for manned aircraft for description of the noise directivity patterns. But a previous measurement determined that a refinement of these methods was required for the application to drone noise. One of these refinements was the use of a larger truss support rig, which was selected
to provide sufficient clearance for the aircraft. The rig also provided regular holes where the microphones’ support arms could be mounted; the rigid structure possessed no flat faces and minimal cylindrical truss structures to minimize scattering of reflected signals. In addition to
the lighting rig array, a number of additional microphones were placed along the flight path, and in-plane but outside of the measurement array for validation of the acoustic sources. With this improved array, another measurement of a multi-rotor aircraft was conducted, equivalent acoustic
sources constructed, and validation performed. This measurement validates the use of the square array to characterize these types of aircraft.
Reduction of sheets requirement for Slow Printing Operations at Noise Measurement Procedure in ECMA-74 Annex C
Authors: Kitamura Takeshi
Published: July 2024

Inkjet printers are expanding for its possibilities of printing not only documents but also photos. In ECMA-74, which stipulates measurement method for printer noise, it is required to be measured while printing three or more sheets in order to ensure measurement reproducibility. In
addition, the ISO1120x series, which defines the measurement of sound pressure levels, is required to measure more than 30 seconds. For printers printing for documents, it is not difficult to print three cycles at A4 size paper within 30 seconds. However, printing for photos, there are several
devices take more than 30 seconds to print one A4 sheet in order to print for detail. So, when we preform the measurement during three cycles such as the slow printing operations, it will be necessary to spend more time on the evaluation. Therefore, we compared the measurement value with printing
at 3 sheets or 1 sheet in slow operations more than 30 second to print one sheet. Also, we evaluated in its reproduction conducted at various laboratories. We propose a method for reducing the number of sheets requirement for printers with slow printing operations.
Noise radiation from a partially opened and elevated tunnel-tube
Authors: Probst Wolfgang , Notario Tévar Antonio
Published: July 2024

Road or railway tunnels are considered in noise prediction programs generally by neglecting any emission from the tunnel structure between the openings and replacing each tunnel mouth by additional sources simulating the sound radiated from inside to outside through these openings.
The sound pressure level inside the tunnel can be derived from the analog model of a room formed by a slice cut out of the extended tunnel with two perfect reflecting planes perpendicular to the tunnel axis. The paper presents a methodology for the case of an elevated tunnel tube with an upper
ventilation gap running over the entire length of the tunnel to calculate the sound pressure levels in the surrounding area more approximately using engineering models like ISO 9613-2 or others and more detailed using a particle method developed to account for complete 3-dimensional propagation
problems.
Electromechanical Modeling and Analysis of Motor Whine in Electric Propulsion Systems
Authors: Bhyri Rajeswara Rao , He Song
Published: July 2024

Electric motor whine is a major source of tonal noise and vibration for electric propulsion systems. The lack of engine masking noise in electric vehicles (EVs) further pronounces the pure tones, which are annoying to the occupants. The associated vibration can cause durability issues
due to resonance and lead to failure of the sub-assembly or the supporting structure. A source-level NVH assessment of electric propulsion systems in modern EVs aims to achieve first-time quality designs at the advanced design stage. Accurate modeling of the motor stator and the electromagnetic
(EM) forces at the air gap between the stator and rotor are critical to the NVH assessment. This work investigates the interaction between EM force application and the stator design in all four quadrants in which the electric motor operates, including both driving and regenerative braking
in both clockwise and counterclockwise directions. A finite element (FE) model of the stator is developed, and the EM forces are mapped on the stator teeth, including different clocking and application directions. The stator model is integrated in the electric drive unit (DU) model, which
enables the evaluation of the NVH performance of the propulsion system due to the reversal the EM force directions. The predicted analysis results are compared with the measured mount vibration
HVAC terminal units are too darn loud
Authors: Dickman Jameson , Wilson Rebecca
Published: July 2024

This paper discusses three design trends and their implications for heating, ventilation and air conditioning (HVAC) noise: interior designs resulting in exposed utilities in commercial buildings, particularly in flexible seating and open collaboration areas; improving indoor air quality
by providing clean and fiber-free airstreams in healthcare, research, or educational facilities; and the use of recently developed sensible-cooling terminal units, also known as dedicated outside air system (DOAS) terminal units. Applying traditional noise control strategies to HVAC systems
in these contexts cannot always achieve typical background noise criteria. Design and construction teams must consider alternative strategies which are often relatively extreme in terms of cost, size, and effort. In many cases, the drawbacks of these strategies outweigh their acoustic benefit
and so they are not always implemented, resulting in noisy spaces. This paper argues that the design of HVAC terminal units should be refined to reduce generated noise. This would allow customers more flexibility when using terminal units and ultimately reduce noise impacting building occupants
across all industries.
Estimation of blocked forces for NVH source characterization of a beam axle using analytical methods
Authors: Braun William , Ambarisha Vijaya Kumar , Sun Zhaohui
Published: July 2024

Component-Based Transfer Path Analysis (TPA) has been of growing interest recently because, unlike classical TPA, it enables source characterization independent of the receiver structure. The source energy in component TPA is typically characterized by blocked forces. As part of virtual
prototyping, OEMs have interest in building a library of component/subsystem models that may be "plugged" into larger system models. For an OEM supplier, it is imperative to have the capability to provide subsystem models along with source energy characterized in component blocked
force prior to availability of physical parts to support virtual validation and optimization efforts for seamless system integration. In this paper, three methods of blocked force calculation are considered: Direct, Free Velocity and In-situ. A Finite Element Analysis (FEA) model is used to
Directly calculate the blocked forces exerted by a rear beam axle at the vehicle attachment points, then to simulate how they might be estimated in a dynamometer test stand using the Free Velocity or In-situ methods, with the aim of offering practical guidance for both scenarios. Assumptions
regarding input and output boundary conditions, along with three versus six degree-of-freedom (DOF) attachment paths, affecting both the analytical and test-based estimation of blocked forces, are also scrutinized.