bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptual adaptation to unfamiliar dialect variation
Authors: Lilley Kevin D. , Clopper Cynthia G.
Published: July 2024

Regional varieties of a language often differ in the phonetic realization of shared phonological categories, resulting in perceptual ambiguity. In perceptual tasks, listeners with more exposure to regional dialect variation perform differently than listeners with less exposure, reflecting underlying differences in lexical competition. In this study, we examined perceptual adaptation to one authentic dialect of American English and one novel dialect to test for adaptation to unfamiliar variation. Our materials contained contrasts that are perceptually ambiguous in Southern American English and in the novel dialect we created, in which linguistically trained bilinguals substituted English /ow/ with Spanish /o/. Participants heard a familiarization passage spoken in a Southern or Novel dialect and then completed an auditory lexical decision task. Adaptation was assessed by differences in accuracy and response times for each vowel contrast, talker dialect, and familiarization dialect. Results revealed lower accuracy and slower response times for both target contrasts when pronounced in their respective dialects. These effects reflect the difficulty in processing perceptually ambiguous stimuli. Familiarization dialect had no effect on accuracy or response times; future analyses will include quantification of listener regional dialect exposure to better assess its influence on processing novel variation.
An ultrasound investigation of Hnaring Lutuv (high?) vowels
Authors: Ziegler Grayson , Bohnert Amanda , Berkson Kelly H. , Par Sui Hnem
Published: July 2024

Lutuv (also known as Lautu) is an under-documented Chin language from the Tibeto-Burman language family spoken by 18,000 people, both in Chin State in western Burma and in diaspora communities worldwide, including approximately 1000 people in the Indianapolis Chin refugee community. Lutuv utilizes a typologically rare six-way contrast in the higher part of the vowel space (i y ɨ ʉ ɯ u, see Bohnert et al. 2022), with an additional four high diphthongized vowels (ie̯ yə̯ ɯə̯ uo̯). Previous work has also identified that the high central vowels (/ɨ ʉ/) are poorly disambiguated—acoustically, they show considerable overlap with both each other and the high back vowels, and in terms of lip posture, they do not display the characteristics of a typical rounding contrast (Bohnert & Berkson 2023). The present work utilizes 3D ultrasonography to provide detailed lingual articulatory data of Lutuv vowels with special attention paid to the high central vowels, adding a new dimension to the existing acoustic and articulatory data. Real-time images of tongue position and motion provide new insights into the complex articulatory gestures involved in the production of these sounds and constitute the first ultrasound investigation into this underdocumented language.
Temporal change of seafloor scattering and its dependence on environmental parameters in shallow-water sandy sites
Authors: Hare Jenna , Lyons Anthony P. , Venegas Gabriel R.
Published: July 2024

In the ocean, the performance of active sonar systems used for object detection and seafloor characterization can be affected when the acoustic properties of the seafloor change due to near-bottom hydrodynamics and biological activity. Determining the dominant environmental mechanisms and corresponding time scales that regulate seafloor scattering will increase our understanding of the performance of these remote-sensing applications. To this end, a high-frequency active acoustic system (operating at 38 kHz, 70 kHz and 200 kHz), a wave-sensing CTD, and a stereo camera were deployed on the seafloor in a series of experiments lasting from two weeks to five months. Seafloor scattering measurements were obtained in two shallow water locations in New Hampshire, USA: a wave-dominated site and a tidal current dominated site. Daily and weekly trends in mean scattered levels and the mechanisms causing their temporal variability are discussed. The temporal change in scattering as a function of angle is compared to the small-slope approximation model where seafloor roughness estimates were obtained using stereophotogrammetry.
The effect of microfabric heterogeneity on shear wave properties in fine-grained sediments
Authors: Venegas Gabriel R. , Chao Yu-Hsuan , McCue Jane , Kim Kang , Cormack John M.
Published: July 2024

The water-sediment interface is highly susceptible to physical, biological, and chemical processes, which can create significant levels of heterogeneity in sediment biogeoacoustic properties at various spatial scales that affect transmission and scattering of elastic waves. Using a suite of microscopy, spectroscopy, and medical sonoelastography techniques, relationships between heterogeneity in the sediment microfabric and shear wave speed can be investigated at spatial scales ranging from centimeters to micrometers. Here, we study fine-grained sediments extracted from two unique intertidal mudflats in the Great Bay Estuary, New Hampshire, USA. Shear waves were excited via acoustic radiation force and external vibration in the 50–200 Hz frequency band, and particle velocity was sensed in the top 2 centimeters of sediment at approximately 0.5-micrometer spatial resolution using a research-grade medical imaging array. By directly imaging the propagating shear wave, spatial heterogeneity of shear wave speed was directly measured. Next, subsamples were extracted and prepared for microscopy, where volume fraction and orientation of organic, mineral, and aqueous components were studied at various spatial scales. A comparison of between shear wave speed and microfabric parameters will be presented. [Work sponsored by ONR.]
Celebrating the life and achievements of Jerry Christoff
Authors: Rawlings Samantha , Lo Verde John , Dong Wayland
Published: July 2024

Jerry spent 61 years of his life in the service of acoustics. He was one of the first people hired by one of the first established acoustical firms in the United States, moving from staff engineer to firm Principal. Jerry started with designing and developing microphones early in his career, followed by his work in auditorium acoustics, remnants of which we still see in today’s auditorium design practices. Later in his career, Jerry worked on improving the measurement methods for exterior façade noise reduction evaluation, and ultimately on HVAC noise study and improvements. Jerry has done it all and left the acoustical community better than he found it. Come join us in celebrating his life and his achievements during this special session.
Spatiotemporal patterns of fish chorusing in California National Marine Sanctuaries
Authors: Kim Ella B. , Kok Annebelle , Donahue Emily , Beretta Emma , Hatch Leila , Joseph John E. , Margolina Tetyana , Peavey Reeves Lindsey , Baumann-Pickering Simone
Published: July 2024

In aggregations, some male fish will sing together in “chorus” for hours, to attract female mates. Through analyzing passive acoustic data, one can determine which, when, and where fish are chorusing, to identify breeding grounds, species distributions, and mating seasons. National marine sanctuaries aim to protect marine ecosystems, particularly breeding and feeding grounds for at risk species. Through the Sanctuary Soundscape Monitoring project, a cumulative 17.9 years of passive acoustic data were manually analyzed for fish chorusing in Monterey Bay, Channel Islands, and proposed Chumash Heritage National Marine Sanctuaries. We aimed to determine which fish were chorusing within the sanctuaries, where and when they occurred, and if fish were engaging in acoustic niche partitioning (minimizing overlap in time/frequency to reduce competition). We found five unique fish choruses including plainfin midshipman, bocaccio rockfish, white seabass, and two unidentified fish choruses, which showed distinct diel, seasonal, and spatial preferences. Fish were found to partition acoustic space in frequency but not in time. Understanding fish reproductive habitat and behavior within sanctuaries is crucial for safeguarding threatened fish species. Moreover, studying fish chorusing is a powerful tool to noninvasively monitor fish to understand their reproductive habits, with goals of better protecting them.
Particle motion polarization of offshore fish vocalizations, boat noise, and ambient soundscapes
Authors: Jones Ian T. , Bonnel Julien
Published: July 2024

Acoustic particle motion is an important acoustic cue for fish and aquatic invertebrate hearing. When reported for bioacoustics applications, it is often described as a magnitude only. However, particle motion is a vector quantity with polarization information (including directionality) relevant to detection and localization of sound cues by fishes and invertebrates. This study applied established metrics of particle motion polarization including ellipse amplitude, angle, orientation, and degree of polarization, to compare sounds of fish vocalizations with that of boat and ambient sounds at a 900 m-deep site (in the Atlantic Deepwater Ecosystem Observatory Network) offshore of Florida. Polarization metrics were computed for bivariate signals in the plane formed by the horizontal source-receiver and vertical axes. Boat sound polarization was quantified at multiple distances from the closest point of approach. Fish and boat sounds had narrower particle motion ellipses and larger amplitudes in the horizontal compared to ambient sounds that were more circular with larger relative vertical amplitudes. Fish and boat sounds were often strongly polarized, which may allow spatial release from masking given sufficient angular separation of sounds. This analysis framework has promising applications for monitoring in situ directionality of fish and other animal vocalizations and for modelling directional masking.
A comparison of tidal components across multiple sites using ultra-low frequency ocean acoustic measurements
Authors: Eller Anthony , Heaney Kevin D.
Published: July 2024

Recent long-term analysis of the hydrophone measurements taken in the deep sea reveals indications of multiple tidal components. Tidal harmonics corresponding to solar and lunar diurnal and semi-diurnal tide components were determined by analyzing the Cepstrum (variance of a spectral power) of the year or more long time series (0.5 Hz) of mid-water column measurements taken by the United Nations Comprehensive Test Ban Treaty Organization (CTBTO) in the Pacific, Atlantic and Indian Ocean. Postulations for the origin of this signal include rolling rocks, ocean turbulence, a change in the surface height, currents, mechanical/electrical (non-acoustic) noise and wind/wave induced noise propagating in the ocean. In this paper, this work is extended to more sites and encompasses a larger portion of the ultra-low frequency range (i < 5 Hz). it is found that different sites have quite different tidal components (as expected) but also have different frequency components (some with 0.5–1 Hz and others with 3–5 Hz). This opens the possibility of acoustic soundscape differences between sites due to regional source generation and local acoustic propagation.
Comparing coastal marine habitats by combining passive acoustics with metagenomics
Authors: Milne Grant A. , Miksis-Olds Jennifer , Stasse Alyssa , Lee Bo-Young , Wilford Dylan , Baruah Shaurya , Brown Bonnie
Published: July 2024

Past studies have combined passive acoustic monitoring with environmental genetic methods to detect target organisms, however, no studies to date have employed metagenomics concurrent with passive acoustic monitoring of soundscapes for comparison of marine habitats. The present study used both approaches simultaneously for holistic observation of marine habitats to reveal information beyond using either technique independently. Water samples for metabarcoding (four primer sets) were collected during periods of passive acoustic monitoring from three different marine habitats, each at four different geographic locations along the New Hampshire/Maine coastlines. Multivariate analyses compared discrimination among habitat types and geographic locations by analyzing acoustic metrics generated using the Soundscape Code and metagenomic taxonomic assignments. Passive acoustic monitoring provided insight into environmental features that were unobservable with metagenomics, especially anthropogenic activity and geophysical processes, whereas metagenomics provided a more complete picture of the biological composition of habitats through detection of organisms that were not actively producing sound. This enables simultaneous evaluation of biological and functional connectivity of marine habitats by detecting what organisms are present and their contributions to the soundscape. In future, genetic and acoustic indicators will be used for prediction of substrate characteristics and sound sources to model acoustic propagation environments.
Ultrasonically induced electrical potentials in PLLA film and bone
Authors: Kitajima Shouta , Maehara Keigo , Matsukawa Mami
Published: July 2024

Osteosynthesis materials are used for the fixed treatment of serious bone fractures. Titanium and bioabsorbable poly-L-lactic acid (PLLA) are often used. PLLA is known to have piezoelectricity, and its contribution to bone fracture healing has been discussed. On the other hand, bone fracture healing using low-intensity-pulsed-ultra-sound (LIPUS) is also popular although the initial mechanism (how bones sense ultrasound) is still unclear. One key factor is the weak piezoelectricity of bone. If ultrasound was able to induce higher electrical potentials in PLLA than in bone, the combination treatment of PLLA and LIPUS would be effective for bone fracture healing. Then, we experimentally investigated the piezoelectricity of PLLA and bone in the MHz range. First, we fabricated an ultrasonic receiver using a cortical bone plate (thickness 1 mm) covered by a stretched PLLA film (thickness 50 mm) as a piezoelectric material. Second, we irradiated ultrasound in the MHz range to the receiver and measured electrical potentials as the output of the receiver. As a result, the average electrical potentials were about 1.4 times higher than those of a receiver made of bone without the PLLA film. This result indicates that ultrasonically induced potentials around bone may increase by the PLLA film.
Extended playing techniques as a source of unusual acoustic phenomena to explore with music students
Authors: Pàmies-Vilà Montserrat
Published: July 2024

When teaching acoustics, instructors typically consider musical instruments to introduce students to the science of sound. Common examples, such as the flute as an open pipe or the behavior of a string fixed at both ends, are often used to illustrate the acoustics of musical instruments. In addition, when teaching acoustics to advanced musicians, one could take advantage of the precise prior knowledge that students have regarding both conventional and extended playing techniques. When using extended techniques, musicians may incorporate unusual ways of producing sound with their instruments, as is often found in contemporary classical compositions. This unusual sound production might even result in a counterexample to the classical textbook case. For example, the so-called slap-tongue technique on the saxophone or clarinet produces a free (and highly damped) oscillation of the reed, which contrasts with the self-sustained oscillations of the reed if the instrument is blown as usual. Based on insights gathered during an introductory course in musical acoustics at the mdw—University of Music and Performing Arts Vienna, this paper highlights how extended techniques not only challenge our understanding of musical acoustics but also serve as interesting phenomena to explore interactively with students in the lecture room.
An open-source project for wind instrument modeling using digital waveguides
Authors: Scavone Gary
Published: July 2024

Digital waveguide methods for time-domain modeling of acoustic structures comprised of interconnected piece-wise one-dimensional cylinders, cones and toneholes have been well reported in the past. In this work, an open-source Matlab class is presented that can be used to model arbitrary wind instrument air column structures, defined by length, radii and hole geometric parameters, using digital waveguide methods. Fractional-delay filtering can be enabled or disabled, with support for both Thiran and Lagrange filter types of specified order. Thermoviscous losses can be modeling using either a discrete-time least squares or a shelf-filter fit, both of arbitrary order. Three different tonehole model options are provided (two-port, three-port or wave digital filter). End boundary conditions include closed, anechoic, ideally open, open flanged and open unflanged. The class object can be used either in single-sample iterative contexts (for example, with an attached excitation model) or with arbitrarily-sized input signals (for example, to compute a reflection function or impedance). The modeled geometry can be constructed manually by iteratively adding segments or holes, or a complete geometry can be specified in a file. This project is bundled together with a parallel and previously reported open-source project for frequency-domain transfer matrix modeling of air columns (https://github.com/garyscavone/acmt).
Identifying noise control strategies for variable air volume (VAV) boxes in acute care hospital design
Authors: Carolina Jessica
Published: July 2024

Variable air volume boxes are frequently used within new acute care hospital design of heating, ventilation and air conditioning systems in Canada. Spatial and room-use noise limits as defined within the project requirements [PM1] are often necessarily onerous to provide acoustical conditions that promote well-being and patient recovery, with appropriate noise control design crucial to the success of meeting the project requirements. Additionally, the desire for fiber-free linings to ductwork exacerbates the noise control limitations. This paper will review the available noise control strategies, the acoustic performance of fiber-free variable air volume box types with and without an attenuator and identify cost-benefits to the Design-Builder. This study will demonstrate how the implementation of a variety of variable air volume box models, sizes, operating conditions, pressure drops are affecting the noise performance. This study will summarize the appropriate variable air volume box types and design conditions that meet the project noise limits used in Canadian healthcare standards such as CSA Z8000, LEED and other provincial technical guidelines.
Influence of refracting atmospheric profiles on trace velocity and arrival time
Authors: White Michael J. , Blevins Matthew G.
Published: July 2024

The influence of the atmospheric profile on the trace velocity and arrival time has received little attention, although these properties of sound propagation are important for direction finding and localization. The refracting temperature profile causes the received sound to be delayed or advanced in time compared to that for the temperature at ground height, and the situation is made anisotropic in the presence of wind. We consider refraction by linear temperature and logarithmic wind profiles on the trace velocity and arrival time for distant impulses received at the ground, and use this information in small arrays for direction finding and large arrays for localization.
Verifying turbulence models in the atmospheric boundary layer by acoustical means
Authors: Wilson D. Keith , Ostashev Vladimir E. , Hart Carl R. , Kamrath Matthew J.
Published: July 2024

The impacts of turbulence on sound propagation in the atmospheric boundary layer (ABL) are important in many practical applications such as acoustic source localization, sonic boom propagation, and auralization of flying aircraft. However, turbulence impacts can vary dramatically in response to changing meteorological conditions. To address this issue, a turbulence spectral model has been introduced that captures the complexities of turbulence generation by wind shear, buoyancy instabilities, and ground blocking in the ABL. An experiment on vertical and slanted sound propagation through the ABL was conducted to verify the model. Various statistical characteristics of sound signals, including variances of the log-amplitude and phase fluctuations, coherences, and signal probability distributions were measured and compared to theoretical predictions. The dependence of the statistics on meteorological conditions was found to be accurately predicted in conditions of well-developed turbulence, as occurs in windy conditions and the daytime. Predictions in conditions of weak and intermittent turbulence, as often occur at night and around sunrise and sunset, remain challenging.
Degradation monitoring of multilayer ceramic capacitors during high accelerated lifetime testing using ultrasound
Authors: Jones Haley N. , Arguelles Andrea P. , Trolier-McKinstry Susan
Published: July 2024

Multilayer ceramic capacitors (MLCCs) are vital circuitry components where long-term stability at high temperature and fields is critical to device operation. High accelerated lifetime testing (HALT) statistically investigates reliability and lifetime of MLCCs through exposure to temperatures and voltages exceeding normal operating conditions. The long-term reliability of the dielectric layers in MLCCs strongly depends on potential variability in the dielectric microstructure, such as cracking, which can be challenging to detect. Nondestructive ultrasonic evaluation is sensitive to microstructural changes through measurements of wave scattering. This work uses high frequency (100 MHz) focused ultrasonic scattering methods to nondestructively monitor structural and microstructural changes in MLCCs from the pristine to the failed state during HALT to understand structural origins of electrical failure. Printed circuit board mounted MLCCs were electrically and ultrasonically characterized in a pristine state and during various degraded states before and after electrical failure under HALT. Evidence of damage pre-HALT was ultrasonically indicated by high attenuation regions on the ultrasonic maps suggesting that the mounting process may induce damage. The high attenuation regions in the pristine samples evolved throughout HALT indicating that the damage in the pristine state might be the spatial origin of part failure, which underscores the impact and importance of detection of structural defects on the reliability of MLCCs.
Fundamental acoustics concepts taught through the development of an impedance tube
Authors: Geib Nathan P. , Pham Allan , Naify Christina
Published: July 2024

As part of its mission to educate students, Applied Research Laboratories, The University of Texas at Austin (ARL:UT) employs student technicians to assist on a variety of ongoing research projects. Recently, an undergraduate student technician was tasked with the design and fabrication of a low-cost impedance tube for use in characterizing acoustic materials. To assist the student in developing a set of design requirements, and to determine whether preliminary data were being accurately collected and processed, a set of homework problems were developed to teach the student the fundamental concepts in acoustics necessary for impedance tube development. Homework problems required utilizing both travelling- and standing-wave solutions to the one-dimensional (1D) Helmholtz equation, as well as a basic understanding of the relationships between pressure, particle velocity, and acoustic impedance. Homework solutions were compared with 3D finite element simulations and with experimental data collected using the impedance tube. We felt that these homework problems were effective at conveying basic ideas in acoustics to a student with no prior knowledge in the subject, and how those concepts could be used to solve real-world problems.
Lord Rayleigh versus Chladni and KFC Sanders: Who is correct about tuning forks?
Authors: Russell Daniel A.
Published: July 2024

The tuning fork is one of my favorite pieces of acoustical apparatus (as evidenced by three published papers in the American Journal of Physics and an article in Acoustics Today). A favorite problem (formerly used on final exams, and currently used as a hands-on activity) for the first-year graduate structural vibrations course I teach, requires students to read excerpts from four textbooks which make a statement about the boundary conditions for the tines of a tuning fork. Lord Rayleigh and Barton describe a tuning fork as two fixed-free bars joined at the base, while Chladni and Kinsler, Frey, Coppens, and Sanders describe a tuning fork as free-free bar bent into a U- shape. Who is correct? Students are required to measure the frequency spectrum of a tuning fork and match the resulting frequency ratios to what they would obtain by solving the boundary condition problem by treating the fork tines as a free-free or fixed-free bar undergoing flexural vibrations. This talk will work through the problem and will illustrate some of the pitfalls that often trip up students. And yes, the question of who is correct will be answered!
Performance evaluation of decision trees and multilayer perceptrons in seabed classification
Authors: Rios Diego , Tokuda Jack , Michalopoulou Zoi-Heleni
Published: July 2024

Accurate knowledge of the oceanic propagation medium, and, thus, seabed properties, is of paramount importance in source localization, especially of weak targets. In this work, we employ machine learning techniques to perform seabed identification and classification using impulse responses of different media; supervised learning is employed. We first design a decision tree architecture that relies on features selected from the impulse responses corresponding to the different media. Examples of these features are kurtosis, skewness, and strength of the signal. Training sets are created by identifying features from noisy signals and testing follows after extracting corresponding features from a different data set. Performance is evaluated as a function of Signal-to-Noise Ratio. A principal component analysis is also implemented for the investigation of the potential for dimensionality reduction. Subsequently, multilayer perceptrons are employed using identical data both for training and testing and the two machine learning techniques are compared; advantages and disadvantages of each are identified and discussed in this work. [Work supported by ONR.]
Inference of geoacoustic model parameters from acoustic field data: Perspectives on Geoacoustic Inversion
Authors: Chapman Ross
Published: July 2024

Estimation of parameters of geoacoustic models from acoustic field data has been a central research theme in acoustical oceanography and ocean acoustics. During the past several decades, highly efficient numerical inversion techniques have been developed that provide model parameter estimates and their uncertainties based on statistical inference methods. However, the methods are model-based and the inversions are prone to errors related to model mismatch. In any event, the inversions can generate only effective models of the true structure of the ocean bottom, which is generally highly variable over relatively small spatial scales in range and depth. There are also questions about the theory for modelling sound propagation in porous sediment media that raise doubt about the validity of inversion results. In most inversions, a visco-elastic theory is used, but is this the most appropriate propagation model? Another question is about the impact of neglecting shear waves in geoacoustic models. Most inversions assume a fluid model of the ocean bottom. This paper revisits issues that have raised questions about limitations of geoacoustic inversion methods, and discusses the impact of various mitigation measures that have been applied. The paper concludes with musings about new inversion techniques based on machine learning.
Impact sound insulation performance of mass timber floors
Authors: Zhou Jianhui , Jafari Mohammad Hossein A.
Published: July 2024

Mass timber floors are being used increasingly in both mass timber and hybrid timber buildings due to its dry and rapid construction. Bare mass timber structural slabs have relatively low impact sound insulation performance. Though certain floating floor assemblies on mass timber slabs can provide adequate single number ratings, such assemblies are mainly effective in the middle to high frequency range. This paper will provide an overview of the research on the impact sound insulation perforamnce of mass timber floors with exposed ceiling and floating floor assembies conducted at the Universtiy of Northern British Columbia. The test data of bare mass timber floors, with continous floating concrete toppings, with raised discrete floating floor assemblies will be presented and compared. The effect of interlayer, concrete thickness and excitation sources on the single number ratings and frequency spectra will be discussed. Recommendations for future reseach will be given based on the discussion.
Vibroacoustic performance of a mass timber cassette floor through mock-up tests
Authors: Zhou Jianhui , Guo Chenyue , Jafari Mohammad Hossein A. , York Brant
Published: July 2024

Though cross laminated timber slab floors are being used increasingly in mass timber construction, solid mass timber slab floors are limited to short-to-medium span applications. The sound insulation performance of solid mass timber slab floors is often achieved through assemblies on the floor surface as exposed wood ceilings are often prefered by achitects and occupants. A mass timber cassete floor system has been recently designed and tested for its structural, vibrational and acoustical performance. This paper reports the vibroacoustic performance of the proprietary floor system through mock-up building tests. In particular, the natural frequency and mode shapes of the floor under 200 Hz was measured by experimental modal tests. The effect of floating concrete topping on the dynamic properties of the floor was assessed by experimental modal testing. The impact sound insulation performance of the bare cassette floor was first measured, and then with floating concrete toppings. The airborne sound insulation performance of a partition wall was measured to reveal the effect of flanking sound casued by the exposed continous mass timber ceiling. Detailed results will be presented in the full paper.
Use of a micro acoustic chamber for rapid iterative design, teaching, and demonstration in the development of innovative lower-carbon mass timber assemblies
Authors: Fretz Mark , Stenson Jason , Northcutt Dale
Published: July 2024

Mass timber construction offers a range of benefits to the design industry, including the potential for sustainability and reduced building embodied carbon, biophilia, speed of assembly, and prefabrication. However, these benefits can create acoustical challenges for sound isolation between spaces. Thus, the University of Oregon’s Institute for Health in the Built Environment, in collaboration with the TallWood Design Institute, has developed a micro acoustic chamber as a conceptual testbed, educational resource, and demonstration tool for design professionals and students, to develop new and innovative mass timber acoustic assemblies, understand acoustic implications of material choices in composite form, and comparatively analyze the performance of acoustic detailing decisions more rapidly at a small scale. The chamber hosts specimens that are 813 mm × 813 mm and up to 300 mm thick, far smaller than a typical laboratory acoustic floor/ceiling assembly test chamber, creating known limitations; however, test samples can be cost and material efficient, allowing relative performance differences between assemblies to be evaluated quickly and easily for initial design feedback. This presentation will share how the use of a micro acoustic chamber has been integrated into design education, student, and industry pilot research to accelerate the development of mass timber acoustic solutions.
Using a biomimetic sonar bat robot to explore the sensory world of bats in the field and in the laboratory
Authors: Rock Nicholas , Müller Rolf
Published: July 2024

Bat species such as those belonging to the families of horseshoe and Old World leaf-nosed bats make their navigation decisions based on echoes that are often received from dense vegetation. To gain an understanding of how these animals accomplish navigation based on such complicated clutter echoes, a biomimetic sonar system that replicates the auditory periphery of bats has been used as synthetic observer to probe the sensory stimulus ensemble of the bats in a flight tunnel as well as in the field. Both laboratory and field experiments were carried out in Brunei on the island of Borneo. For the flight tunnel, the biomimetic sonar robot has been used to record a large number of pulse and echo pairs in conjunction with an array consisting of 28 ultrasonic microphones. In this experiment, the sonar head was positioned at points spaced on a 3d grid that covers the tunnel's volume. This data set will be used to train a deep neural network to predict the inputs to the ears of a bat maneuvering in the tunnel. In the field experiments, the sonar head was carried off road in various tropical-forest habitats to record echo samples in conjunction with precise GPS location references.
Validation of mSOUND using a fully heterogeneous skull model
Authors: Bell Jeff J. , Xu Lu , Chen Hong , Jing Yun
Published: July 2024

Transcranial ultrasound has found an increasing number of applications in recent years, including the treatment of neurological conditions through thermal ablation and neuromodulation. Ensuring the success and safety of such treatments necessitates precise numerical simulations of transcranial ultrasound, a pivotal aspect of treatment planning involving phase correction. Addressing this demand, an open-source wave solver named mSOUND (https://m-sound.github.io/mSOUND/home) was developed specifically for modeling focused ultrasound in heterogeneous media. A recent intercomparison study (J. Acoust. Soc. Am. 152, 1003–1019, 2022) scrutinized mSOUND alongside other wave solvers like k-Wave, demonstrating its accuracy in modeling wave propagation through a homogeneous skull. This study extends the assessment to evaluate mSOUND's accuracy in modeling wave propagation through a fully heterogeneous skull, utilizing CT images of an ex vivo human skull. The obtained results are systematically compared with those from k-Wave, revealing a high level of agreement.
Gold nanoparticle-coating reduces the acoustic pressure threshold for nanodroplet vaporization
Authors: Mistry Nishita , Dhawan Ruchika , Mercado-Shekhar Karla Patricia
Published: July 2024

Nanodroplets with a low-boiling-point perfluorocarbon (PFC) may vaporize spontaneously at physiological temperatures. Using a high-boiling-point PFC, e.g., perfluorohexane (PFH), can enable ultrasound-triggered vaporization for applications in imaging and drug delivery. However, PFH requires relatively high ultrasound (US) pressures for vaporization compared to low-boiling-point PFCs, making its use challenging. We investigated the feasibility of reducing the vaporization threshold by gold-coating lipid-encapsulated PFH nanodroplets (Au-PFH-NDs). We synthesized Au-PFH-NDs with 200 nm mean particle size and 5.12 × 10−4 pg mass of gold-coating per nanodroplet. B-mode images of the emulsion perfused in a flow phantom were used to determine the pressure threshold for ND vaporization upon exposure to 2 MHz focused US (f-number of 1.27, 0.5% duty cycle). The pressure threshold for Au-PFH-NDs (3.97 ± 0.63 MPa) was significantly lower (p < 0.05) than that of NDs without gold-coating (7.07 ± 0.02 MPa), indicating that gold-coating reduced the vaporization pressure threshold. In addition, the pressure threshold of the Au-PFH-NDs was not significantly different (p > 0.05) from that of perfluoropentane (PFP) NDs (4.16 ± 0.01 MPa). These results suggest that the Au-PFH-NDs can be vaporized at similar pressures as PFP NDs, but are more stable at physiological temperatures. These findings are the first step towards employing gold-coated PFC nanodroplets with a lower vaporization pressure threshold for multimodal imaging and drug delivery.
Predicting sound transmission loss in particle-reinforced polymer composites using machine learning: A comparative study with experimental and theoretical results
Authors: Mago Jonty , Jaish Sunali , Negi Ashutosh , Bolton J. S. , Fatima S
Published: July 2024

In this study, the use of machine learning (ML) models to predict sound transmission loss (STL) in particle-reinforced polymer composites has been examined. The work included extensive literature research and data extraction for training various ML models, focusing on their effectiveness in accurately predicting STL, which is crucial for evaluating acoustic performance. The method involves processing data and applying it to different ML algorithms, with the models calibrated and tested for reliability. A key aspect is comparing these models' predictions with actual experimental results and theoretical models based on the mass law in acoustics. The findings reveal the potential and limitations of ML in materials science, showing their accuracy in predicting STL and comparing them with traditional theories. This research advances the use of data-driven methods in developing and assessing acoustic materials, significantly impacting materials science and machine learning.
Investigation of speed and altitude effects on sound exposure level calculations for multiple helicopters
Authors: Houston Mary L. , Pascioni Kyle , Stephenson James
Published: July 2024

International and United States Federal regulations evaluate helicopter acoustic emissions for certification purposes as well as community noise impact assessments. The Sound Exposure Level (SEL) is a commonly used metric that represents the loudness of a single event, with a penalty for duration. For example, a flyover lasting ten seconds can have the same SEL as a five-second duration flyover that is 6 dB higher in peak level. Ten helicopters spanning the light and medium weight classes were modeled using flight test data. They were then virtually flown using the Advanced Acoustic Model at multiple speeds and altitudes. SEL and A-weighted SEL (SELA) were calculated at ground-based observer locations for each condition. Scaling laws with altitude are determined, and cruising airspeeds which result in the minimum SEL are found. Implications for future land-use planning will be discussed, and the relationships are reduced to general or vehicle-specific operational guidance for pilots.
Microphone diaphragm thermal noise floor measurement using a laser vibrometer
Authors: Karimi Morteza , Lai Junpeng , Pourghader Johar , Miles Ronald
Published: July 2024

The response of a microphone to thermal noise can be extremely difficult to predict and can adversely affect the performance of a given design. The direct measurement of the thermal noise floor of a microphone diaphragm could greatly improve our understanding of the parameters that affect the noise performance. A laser vibrometer can serve as a powerful tool, enabling precise and non-intrusive measurements of the diaphragm thermal noise. The experimental setup for measuring the diaphragm thermal noise using a laser vibrometer is described. Having both the noise floor, and the response to sound for a given microphone, the sound pressure-referred noise floor can be estimated. Measured and predicted results are presented for a variety of microphones. These measured results describe how design parameters, such as the size of the diaphragm, the dimensions of the backside volume, and overall geometry, impact the thermal noise floor measurements.
Acoustic ground effects simulations from asteroid disruption via the “Pulverize It” method
Authors: Bailey Brin , Cohen Alexander N. , Lubin Philip , Robertson Darrel K. , Boslough Mark , Egan Sasha , Silber Elizabeth
Published: July 2024

Our simulations show that PI (“Pulverize It”), a NASA Phase II NIAC study, is an effective multi-modal approach for planetary defense that can operate in extremely short interdiction modes (with intercepts as short as hours prior to atmospheric entry) as well as long interdiction time scales with months to years of warning. The basic process is complete disruption of the threat via fragmentation. In long warning time cases, the fragment cloud spreads enough to miss Earth, resulting in no ground effects. In cases where the warning time is short, the fragments (typically <10 m in diameter) will enter Earth’s atmosphere where their energy is dissipated in a series of ground-level optical pulses and de-correlated shock waves, mitigating any significant damage. We investigate the acoustic ground effects through a set of simulation codes that model the interaction of asteroid fragments with the Earth’s atmosphere following threat interception. Even in the short warning time cases where the fragments enter the atmosphere, our simulations show that threats mitigated by the PI method produce vastly less damage on the ground when compared to the same unfragmented case, yielding shock wave over-pressures under 3 kPa. Our simulations support the proposition that threats sized 20 m—1000 m in diameter can be effectively mitigated through fragmentation, resulting in acoustic ground effects that are below estimated damage thresholds and yield short- and long-term non-lethal effects.
Direct sound printing: Way of manipulating ultrasonic chemistry to print directly engineering structures and remotely inside body
Authors: Foroughi Shervin , Habibi Mohsen , Packirisamy Muthukumaran
Published: July 2024

Direct sound printing (DSP) is a new class of additive manufacturing processes developed in our lab, in which chemical reactions during the 3D printing process are driven by sonochemical route using cavitation bubbles induced by focused ultrasound waves. This invited paper will present methods and possibilities of printing engineering structures with DSP. In addition, this talk will cover a new area called remote distance printing (RDP) and consequent applications. RDP is a new realm introduced by DSP method in which the printing location is not accessible by common energy sources like light or heat. In this situation, ultrasound could penetrate optically opaque materials and conduct printing without direct access to the printing location. This concept opens a wide variety of applications in engineering or medical fields. The focus of this paper is the application of DSP-RDP in biomedical application to print objects inside body without open surgery in a non-invasive manner. Ultrasound penetrates skin and tissues in DSP and is focused on the printing location inside body where the printing material is injected. This work explains DSP in detail and the interaction of the sound with the printing material and how the material is transformed from liquid to solid. The process is demonstrated using a test study conducted using tissue phantoms and also real porcine tissue. This work opens new applications to 3D print with ultrasound where no other 3D printing approaches can achieve.
Internal damping measurements of additive manufactured metal beams
Authors: Jensen Peter K. , Mills Joshua T. , Shepherd Micah
Published: July 2024

Modern additive manufacturing (AM) techniques have created an endless number of new design possibilities. Naturally, it is important to understand how the material properties, including internal damping, differ for AM structures. An experimental procedure has been developed to measure an upper bound for the internal damping of metal beams by minimizing the effects of energy dissipation at the supports and acoustic radiation into the surrounding air. In this talk, measurements for the loss factor of several common metals will be compared to equivalent samples constructed by powder bed fusion at varying angles. The results will also be compared to Zener’s thermoelasticity model, developed for isotropic Euler beams in flexure. Reasons for deviation from theory which arise from the manufacturing technique will be explored.
Sound absorption properties of additively manufactured porous materials with minimal surface pore geometries
Authors: Ciletti Anthony , Brown Martha C. , Sharma Bhisham
Published: July 2024

This study explores the use of additive manufacturing, specifically stereolithography (SLA), to create porous acoustical materials with precise pore geometries for aircraft engine noise reduction. Unlike traditional methods like foaming and fiber-spinning, SLA allows for exact control over pore shapes. Three triply periodic minimal surface (TPMS) pore designs were investigated: split-P, lidinoid, and diamond. These structures were designed through implicit modeling and made from polymeric resin. Their sound absorption capabilities were tested under normal incidence in a two-microphone impedance tube to examine how porosity influences their acoustic performance. Findings revealed unique sound absorption profiles for each geometry, which can be modified by adjusting porosity. Additionally, the static flow resistivity was measured using a raylometer, where results showed that flow resistance is a key factor in their absorption efficiency. Among the three samples, the split-P geometry shows superior sound absorption. This preliminary research highlights the potential of using tailored TPMS geometries in acoustic liners for effective noise control in aerospace applications.
Preceding word information for predicting speech errors in English as foreign language speech
Authors: Moon Ki Woong
Published: July 2024

Speech errors, including disfluency errors (e.g., filled pauses (“uh”, “um”), repetition (“I me-mean right now.”)), and mispronunciation of speech segments (e.g., “think” as /sɪŋk/) are natural occurrences in speech production and they can affect speech fluency and proficiency. Detecting these errors is important, especially in assessing second language (L2) learners. Non-native speakers often produce speech errors, even in read speech, due to increased cognitive load when simultaneously producing the current word and processing the upcoming word. By analyzing two L2 speech corpora having different types of errors (disfluency and mispronunciation), the study aims to assess the effectiveness of incorporating preceding word information in speech error prediction. The results indicate that longer syllable duration in the word preceding the mispronunciation error correlates with error production. The study extends its investigation to identify acoustic and lexical features influenced by the presence of speech errors. The study found that speech errors increase duration of speech. The study also found that words with more syllables may cause L2 speakers to produce speech errors.