bluuebunny/crossref_metadata_2025 huggingface dataset:
Learning to Allocate Time-Bound and Dynamic Tasks to Multiple Robots Using Covariant Attention Neural Networks
Authors: Paul Steve , Chowdhury Souma
Published: July 2024

In various applications of multi-robotics in disaster response, warehouse management, and manufacturing, tasks that are known a priori and tasks added during run time need to be assigned efficiently and without conflicts to robots in the team. This multi-robot task allocation (MRTA) process presents itself as a combinatorial optimization (CO) problem that is usually challenging to be solved in meaningful timescales using typical (mixed)integer (non)linear programming tools. Building on a growing body of work in using graph reinforcement learning to learn search heuristics for such complex CO problems, this paper presents a new graph neural network architecture called the covariant attention mechanism (CAM). CAM can not only generalize but also scale to larger problems than that encountered in training, and handle dynamic tasks. This architecture combines the concept of covariant compositional networks used here to embed the local structures in task graphs, with a context module that encodes the robots’ states. The encoded information is passed onto a decoder designed using multi-head attention mechanism. When applied to a class of MRTA problems with time deadlines, robot ferry range constraints, and multi-trip settings, CAM surpasses a state-of-the-art graph learning approach based on the attention mechanism, as well as a feasible random-walk baseline across various generalizability and scalability tests. Performance of CAM is also found to be at par with a high-performing non-learning baseline called BiG-MRTA, while noting up to a 70-fold improvement in decision-making efficiency over this baseline.
Compact Heat Exchangers With Curved Fins for Hydrogen Turbofan Intercooling
Authors: Patrao Alexandre Capitao , Jonsson Isak , Xisto Carlos
Published: July 2024

Hydrogen is being considered as a possible path toward carbon-neutral aviation. There are additional advantages besides its main benefit of CO2-free combustion. One application is to use it for aero engine heat management due to its cryogenic temperature and high heat capacity, including intercooling and exhaust heat recuperation. The focus of this paper is on the design of a compact heat exchanger (HEX) integrated into an intermediate compressor duct (ICD), which could decrease compression work and specific fuel consumption (SFC). This compact heat exchanger features curved fins to promote flow turning and decrease pressure losses compared to more conventional straight fin heat exchangers. Conceptual design and duct shape optimization has been carried out which produced integrated ICD heat exchanger designs with significantly lower air-side total pressure losses compared to their conventional straight fin counterparts, which could improve system level integration and engine performance. A direct outcome of this study is a pressure loss correlation, which can be used in future engine system-level trade studies.
Releasing genetic biomarkers from cells and tissues with ultrasound
Authors: Zemp Roger J. , Kedarisetti Pradyumna , Wang Joy
Published: July 2024

Ultrasound sonoporation has long been investigated as a means of enhancing therapeutic delivery into cells. More recently, however, ultrasound has been explored as means to liberate biomarkers out of cells. I will discuss our past efforts to enhance ultrasound biomarker release using microbubbles and nanodroplets both in vivo and ex vivo. Our recent in vivo work has demonstrated that ultrasound and nanodroplets can enhance extracellular vesicles and tumor DNA/RNA in the blood by 100-1000-fold. Because we can compare post- sonication blood biomarker levels to a pre-sonication blood draw baseline, and because any increase in biomarkers must be due to ultrasound treatment, this approach is a powerful alternative to biopies with much less tissue damage. In a different paradigm, we are exploring contrast-agent-free ablative acoustic mechanisms on a micro-scale to enhance biomarker release even further. Our group is further exploring novel avenues to detect circulating tumor cells in blood samples, where ultrasound treatment is applied to a separated blood fraction. By detecting biomarkers released from circulating tumor cells but primarily absent in blood cells, our approach is sensitive to single cells. Ongoing work in prostate cancer patients suggest promise for sensitive and specific detection of clinically significant prostate cancer. Ultrasound for biomarker release is a promising avenue of research which could lead to many important clinical applications given additional work and validation.
Improvement of sound absorption of porous materials through periodic holes of sinusoidal decreasing profile
Authors: Laly Zacharie , Panneton Raymond , Atalla Noureddine , Ghinet Sebastian , Mechefske Chris
Published: July 2024

Porous materials used in several engineering applications for noise attenuation present poor acoustic performance at low frequencies. In this paper, a design of porous materials with various periodic decreasing hole profiles is presented and studied using the finite element method. The sound absorption coefficient and the normalized surface impedance are compared for different periodic decreasing hole profiles. A small drop in sound absorption is observed after the first peak with a decreasing linear profile. Using a sinusoidal decreasing hole profile, it is shown that the drop is attenuated. The impacts of the amplitude and the period of the sinusoidal profile on the sound absorption coefficient and the surface impedance are demonstrated. The proposed porous material design with periodic holes having a sinusoidal decreasing profile shows a significant improvement in sound absorption over a large frequency band compared to conventional porous materials.
Influence of social and semantic context in processing speech in noise
Authors: Abassi Etienne , Zatorre Robert
Published: July 2024

Social interactions occupy a substantial part of our life, and listening to others’ interactions is critical in understanding our social world. Although the role of semantics in speech comprehension has been studied, the role of social context, and its interaction with semantics, remain unknown. We conducted a series of four perceptual experiments to better understand the processing of multiple-speaker conversations from a third-person viewpoint, manipulating the social and semantic context of a conversation. We used a stimulus set consisting of two-speaker dialogues or one-speaker monologues (factor: social context) arranged in intact or sentence-scrambled order (factor: semantic context). Each stimuli comprised five sentences, with the fifth sentence embedded in multi-talker babbling noise. This fifth sentence was subsequently repeated without noise, with a single word altered or unchanged. Stimuli were presented to healthy young adults, asked whether the repeated sentence was same as or different from previous in-noise sentence. We found significant effects for both social and semantic contexts when processing a conversation. Our findings highlight that both semantic and social aspects of a conversation can modulate the processing of conversations. These results raise new questions regarding predictive or other mechanisms that may be at play when perceiving speech in social contexts.
Wave-based signal-to-noise enhancement and the shape of cochlear filters
Authors: Altoe Alessandro , Shera Christopher
Published: July 2024

Cochlear transfer functions measured at one location—a.k.a. “cochlear filters”—are characterized by a steep roll-off as the frequency increases above the local best (responding) frequency (BF). The functional role of the sharp “cut-off” is not well understood, although it was previously hypothesized that it plays a major role in encoding sound frequency. Less hypothetical in nature, our work elucidates the role of the steep cut-off in improving signal detection in cochlear-like amplification strategies. We study signal amplification in generic active gain media models and physics-based cochlear models as well. We demonstrate that the optimal strategy for boosting the signal-to-noise ratio (SNR) at a given location “x” requires high gain basal to “x,” followed by rapid attenuation (i.e., sharp cut-off) beyond it. This strategy of amplification followed by a sharp cut-off is precisely how the cochlea processes traveling waves of given frequencies; it boils down to a peculiar form of spatial filtering where waves coming from the “signal side” are amplified, while waves coming from the direction where there is noise but no signal are squelched. This noise “squelching” action manifests in the cochlear filters as the steep high-frequency roll-off.
An open source platform for hearing research
Authors: Clavier Odile , Brooks Chris , Graybill Brian
Published: July 2024

The disparate nature and format of data obtained from existing commercial hearing test systems is a significant impediment to reproducibility of hearing research. Advancement of hearing diagnostic assays requires access to research-grade platforms that are easily customized while enabling broad collaboration across labs with access to varied populations. In this research, we present an open-source platform that combines the Tympan open-source audio processing device with the TabSINT open-source tablet-based hearing software The Tympan uses a Teensy 4.1 processor which leverages the Arduino Development environment, making it accessible to a wide variety of users to create, modify and configure the embedded software. The Tympan is also a powerful audio processing platform that has demonstrated good performance as a hearing aid in a study of 14 adult users with mild to moderate hearing loss. Separately, TabSINT has been used extensively across the Department of Defense for human studies of hearing that include a variety of speech-in-noise tests and questionnaires, with thousands of subjects tested over the past few years. In this project, the two platforms come together, with new hardware extensions, to create a powerful hearing research platform that is extensible and highly accessible, thanks to the low cost of the hardware.
Simultaneous integration of acoustic and environmental data in a graph-based framework for underwater waveguide analysis
Authors: Castro-Correa Jhon A. , Badiey Mohsen
Published: July 2024

Accurate assessment of underwater acoustic propagation relies heavily on understanding variability in the waveguide. Typically, prevailing methods in the field use environmental data exclusively to evaluate water column fluctuations. This study breaks new ground by integrating a graph-based approach, merging insight from acoustics and environmental data to comprehensively analyze ocean fluctuations. The proposed framework leverages data obtained during the Shallow Water ‘06 Experiment (SW06) from a densely measured region in the experimental area. The data used in this work include acoustic broadband signals below 1 kHz from a 48-element L- shape array and environmental measurements from 59 thermistors across 16 mooring arrays, affected by the passing of internal waves. The spatial relationship in the data, facilitated by sensor locations, is harnessed through a graph built upon underlying features from the datasets, providing a nuanced understanding of environmental variability in the water column. The proposed framework is not confined to theoretical constructs; it is substantiated through rigorous model evaluation on the measured data. This validation process robustly demonstrates the generalization power of the proposed architecture, affirming its effectiveness in a highly fluctuating water column and showcasing its potential for advancing underwater acoustic research. [Work supported by ONR Ocean Acoustics program.]
Sound transmission loss of vertical building partitions designed to meet shear structural requirements
Authors: Shafer Benjamin M.
Published: July 2024

Vertical partitions often include structural building elements designed to meet shear requirements. Shear partitions are designed to resist lateral load due to wind or seismic activity and are required in many regions throughout North America. Nightingale et al. completed a 70-assembly series quantifying the effect of shear OSB on the sound transmission loss (STL) of both wood- and steel-framed single-stud assemblies in the National Research Council Canada (NRCC) research report NRCC-45018. This research study builds on the NRCC research with a test of over 200 wood and steel assembly partitions. This research study includes single-, staggered-, and double-stud framing as well as various forms of shear treatment such as OSB Plywood installed on one or both sides of the partition, attachment with various nail attachment patterns, and steel strapping. The effect of these partition elements on the STL will be presented and discussed. Additionally, the effect of sound isolation treatment, such as additional mass, resilient channels, resilient sound isolation clips, and constrained-layer damping will be presented and discussed.
The role of fluid flow patterns in microbubble-mediated endothelial cell membrane permeabilization
Authors: Memari Elahe , Helfield Brandon
Published: July 2024

Blood flow dynamics vary throughout the circulatory system, influencing the pathophysiology of vascular endothelium. We investigated endothelial cell response to ultrasound-stimulated microbubbles across diverse anatomical sites by mimicking assorted blood flow patterns. First, we examined the effect of culture condition on cell sensitivity to sonication by culturing HUVECs either statically or under pulsatile flow (8 or 16 dyn/cm2) for two days. Flow chambers were then co-perfused with microbubbles and propidium iodide under pulsatile flow (8 or 16 dyn/cm2) and sonicated (1MHz, 20 cycles, 1ms PRI, 300kPa) using an acoustically coupled microscope. Additionally, in a subset of studies we investigated ultrasound-assisted endothelial permeability under both pulsatile and oscillatory flow patterns. Compared to static, cells cultured under pulsatile flow resulted in 1.2 to 2.0-fold increase in the percentage of permeabilized endothelial cells (p < 0.0001). Next, compared to sonication under laminar flow (15–30 ml/min), endothelial permeability was significantly augmented under pulsatile flow, ranging from 1.3 to 2.1-fold. Additionally, compared to laminar flow, oscillatory flow at ∼16 ml/min with 0.5 Hz oscillation resulted in a 1.76-fold enhancement in cell perforation, yet yielded no observable permeability at slower flow rates (∼8 ml/min). These findings highlight the influence of local blood flow dynamics on ultrasound-mediated cell permeabilization.
Coupling quantitative ultrasound using echo envelop statistics and shear wave propagation to provide new image contrast of mimicked liver lesions
Authors: Héroux Arnaud , Destrempes François , Cloutier Guy
Published: July 2024

In quantitative ultrasound, biomarkers are sensitive to the scatterers’ positioning and number density, and therefore, shear wave (SW) propagation may modify their time-varying behaviors and provide new image contrast. Herein, we considered echo envelop statistics by using one parameter of the homodyned-K distribution (HKD): the diffuse-to-total signal power ratio 1/(κ+1). A liver lesion-mimicking phantom was simulated with an inclusion and a background of elastic moduli of 40 and 4 kPa, and scatterers’ number densities per resolution cell of 15 and 5, respectively. Ten sets of spatially correlated scatterers were created, and a plane SW was simulated to reposition time and spatially varying scatterers according to the SW motion. Ultrasound images were simulated using MUST with added Gaussian noise to attain 20-dB SNR. Dynamic and static analyses were made over 30 frames with and without SW motion, respectively. Validation was based on the contrast of 1/(κ+1) between the inclusion and the background. HKD image contrast increased with SW motion with values from 0.12 ± 0.10 to 0.48 ± 0.16 (no units) (p  < 0.001). Results suggest that the variation in scatterers’ organization under SW propagation may provide new information over its static counterpart to enhance the contrast of liver lesions.
Application of acoustic metamaterials to phase computing
Authors: Deymier Pierre A. , Runge Keith , Hasan M Arif , Levine Joshua A. , Leamy Michael
Published: July 2024

We review the notion of “phase bit” or “phi-bit” in externally driven nonlinear acoustic metamaterials. Phi-bits are classical analogues of quantum bits, which open pathways to promising and validated modes of initializing, operating, and measuring information. Acoustic metamaterials offer ways to compute information using phase that should compare favorably with state-of-the-art quantum systems without suffering from quantum fragility.
Acoustic metamaterial samples preparation for impedance tube measurements—The influence of different 3D printing techniques and mechanical post-processing on the simulation compliance
Authors: Chojnacki Bartlomiej , Chojak Aleksandra , Pawlik Jan , Binek Wojciech , Idczak Julia
Published: July 2024

Prototyping of acoustic metamaterials frequently involves the use of additive manufacturing techniques. It offers the best price and the option for complex structure production, which is beneficial in the R&D process. Previously, some differences in acoustic metamaterial sound absorption measurement dispersions regarding using 3D printing techniques for sample preparation were noted. The sound absorption sensitivity on different printing settings or materials is usually omitted. The paper will present the research on the impedance tube measurements of absorbing metamaterial manufactured with different 3D printing methods and post-processed with mechanical and chemical treatment. Two approaches to metamaterial construction were analyzed in the current study—the single-solid metamaterial and the structure divided into parts, where the influence of assembly methods was investigated. To achieve the best compatibility with FEM or TMM modeling results, different post-processing techniques were involved, such as drilling, grinding, and sealant use. The presentation will describe the valuable paths used in sample preparation to achieve better compatibility between the measurements and simulations. The need for a comprehensive part preparation description in metamaterials research and papers will be discussed. [Work funded and supported by the Polish Government, National Centre of Research and Development, agreement no. LIDER/11/0065/L-12/20/NCBR/2021.]
A comparison of various steel-string acoustic guitars’ modal response with relation to typical playing styles
Authors: Rau Mark , Scavone Gary
Published: July 2024

Steel-string acoustic guitars are built with large variations in geometry and materials, leading to different-sounding instruments. Musicians will have preferences for geometries or woods depending on certain musical styles or personal preferences regarding tonal characteristics. For example, dreadnought-style guitars with either mahogany or rosewood back and sides and a spruce top are overwhelmingly preferred for bluegrass music. This work presents the beginnings of a project to collect measurements from a vast and varied collection of guitars attempting to span the ranges of guitar woods and geometries. Vibration and acoustic measurements of the instruments are captured and modal analysis is performed to extract the modal frequencies, damping ratios, and amplitudes of the prominent modes. The modal characteristics among them are compared to better understand the most prominent differences with an attempt to learn why certain geometries or woods are preferred for specific genres of music and playing styles. The dataset is continuing to grow and currently includes measurements of twenty different guitars.
Measurements of rocket landing sonic booms from three SpaceX Falcon-9 booster landings
Authors: Anderson Mark C. , Nyborg Kaylee , Gee Kent L.
Published: July 2024

As commercial rocket companies reduce costs, a common strategy is to design reusable rockets. The recovery typically includes propulsively landing the first stage booster near the launch site or on an ocean platform. Because the booster returns at supersonic speeds, a sonic boom is produced. This paper analyzes measurements made of three SpaceX Falcon-9 booster landings at Vandenberg Space Force Base. Each measurement uses multiple microphones surrounding the launch and landing pads at distances varying between 300–25 000 m. The Falcon-9 sonic boom waveforms have three shocks, and all three are consistently measured at every single measurement location. Although the rise times increase with distance, the duration between the shocks shows a more complicated trend, with the farthest measurements sometimes having the same duration as the nearest measurements. Farther than 1 km, the sonic boom peak overpressure can exceed the peak launch noise overpressures. Farther than a few kilometers, the sound exposure level from the sonic booms can be comparable to the exposure during the entire 12 dB-down period for the launch noise. [Research funded in part by the Oak Ridge Institute for Science and Education and Vandenberg Space Force Base.]
Listen to your key: Towards acoustics-based physical key inference
Authors: Ramesh Soundarya , Xiao Rui , Maiti Anindya , Lee Jong Taek , Ramprasad Harini , Kumar Ananda , Jadliwala Murtuza , Han Jun
Published: July 2024

Physical locks are one of the most prevalent mechanisms for securing objects such as doors. While many of these locks are vulnerable to lock-picking, they are still widely used as lock-picking requires specific training with tailored instruments and easily raises suspicion. To overcome the limitations of lockpicking, we propose a novel attack vector that leverages the audio recording of the key insertion in order to infer the shape of victim’s key, namely, bittings (or cut depths) which form the secret of a key. In particular, we show that computing the timing interval between audible click sounds that occur during key insertion enables inferring the bitting information, i.e., shape of the physical key. Such an audio-based attack has several advantages—unlike lock-picking, it minimizes the attacker’s physical access to the lock, thus reducing the risks of them being apprehended. Second, as the attack only requires a microphone to launch the attack (e.g., a smartphone microphone), it significantly lowers the bar for the required expertise of the attacker. Despite the advantages, there are several challenges in extracting the required key-related signal from the audio. In this talk, we will discuss how we overcome the challenges and present initial results depicting the feasibility of audio-based key inference. This talk is based on two conference papers submitted to ACM HotMobile 2020 and USENIX Security 2021 on the same topic.
Acoustic feature analysis of directional sound from parametric array speakers with application to mitigate attacks on voice-activated systems
Authors: Tran Vinh T. , Quinn Kathryn , Norceide Flore , Aoki Emi , Chandra Kavitha , Thompson Charles
Published: July 2024

A number of studies have identified the vulnerabilities of voice-activated devices to attacks from amplitude-demodulated sound from directional speakers. In this research, a controlled set of speech data, both live and played back from directional speakers, is analyzed to identify the acoustic features integral to speaker recognition in smart devices. A category of features, including Mel-frequency cepstral coefficients derived from Mel filter banks, are examined for potential to differentiate and classify speech sources. Potential vulnerabilities in voice-activated systems are systematically identified by examining the acoustic characteristics of diverse voice samples. This analytical approach aims to unveil potential weaknesses that could be exploited, triggering responses from these systems. The findings of this study contribute to the comprehension of the security landscape surrounding voice-activated technologies, paving the way for enhanced cybersecurity measures within this domain.
Acoustic streaming in the Cochlea resulting from periodic excitation
Authors: Keefe Aidan , Thompson Charles
Published: July 2024

This paper presents a model describing acoustic streaming in the scala vestibuli and the scala tympani of the cochlea. The magnitude and spatial features of the acoustic streaming are a function of the vibration of the cochlear partition. Hence, spatial adjustment of the acoustic streaming field can be accomplished by suitable harmonic adjustment of the excitation. It is shown that the dynamic behavior of the fluid is a function of the values of two nondimensional parameters S and R. The Strouhal number S is the ratio of the typical length to the oscillatory particle displacement and the oscillatory Reynolds number R is the ratio of typical length to the oscillatory boundary layer thickness. The method of matched asymptotic expansions is used to obtain a solution that is valid in the limit as 1/S tends to zero. The solution is shown for the slow streaming R/S = O(1) and moderate streaming R/S2 = O(1) cases.
Finite element modeling of infrasound resonance in an underground tunnel structure
Authors: Downey Nathan
Published: July 2024

Recent observations of acoustic/infrasound signals emanating from an underground mine in central Utah show a spectral signature consisting of several dominant harmonics whose amplitude decay rate increases with frequency. This spectral character is consistent with a model in which the observed signals are generated from acoustic resonance within the mine tunnels. I present models of these signals computed using a discontinuous-Galerkin finite element formulation. The mesh geometry of these models is based on the known geometry of the mine tunnels obtained using traditional survey methods. Explosion source locations in the mine are known from previous analysis of seismic signals and operator logs and are associated with observations of infrasound resonance at multiple far-field stations. I explore the sensitivity of the modeled signals to changes in the source spectrum, boundary conditions within in the mine and perturbations to tunnel geometry. I discuss the possible application of my results to volcanic monitoring, industrial monitoring of underground structures, and the possible determination of underground tunnel geometries using far-field observations of acoustic resonance.
The effect of the balloon on balloon-borne infrasound measurements
Authors: Godin Oleg A.
Published: July 2024

Deploying acoustic sensors on free-flying, long-living balloons helps to reach the areas not accessible with the traditional ground-based sensors, reduce flow noise, and improve characterization of various infrasound sources. In particular, instrumented balloons can potentially increase the infrasonic detection range and the early warning lead time for natural hazards, such as tornadoes and avalanches. When assessing the capabilities of balloon-borne infrasonic sensors and interpreting the measurements, it is important to recognize that the balloon inevitably distorts both signals and the ambient infrasound field by scattering the incoming sound. Measurement distortions due to a nearby compact scatterer prove to be rather different from the well-understood effect of a rigid boundary on ground-based sensors. Using the recently developed theory of sound scattering by thin, prestressed elastic shells [O. A. Godin, J. Acoust. Soc. Am. 154, 3223–3236 (2023)], this paper quantifies the effects of hot-air and helium balloons on acoustic pressure and oscillatory velocity. It is found that balloon-borne vector sensors are more susceptible to the distortions than pressure sensors, leading to large differences between the apparent and true source bearing and directionality. Possible approaches to compensate for the distortions and retrieve the free-field acoustic quantities will be discussed.
Prior knowledge benefits older adults' tonal consolidation through talker generalization
Authors: Liu Kangdi , Feng Yan , Qin Zhen
Published: July 2024

Recent research indicated that post-training sleep facilitates memory consolidation and talker generalization in young adults' tone learning. For instance, a nap study showed the newly learned tonal contrast that relates to prior knowledge consolidated more rapidly than that does not after daytime naps. Notably, older adults' declarative memory consolidation is impaired with age-related changes in sleep architecture. The current study examines whether prior (contour-tone) knowledge benefits Mandarin-speaking older adults' Cantonese tone learning. Mandarin employs pitch contours (falling versus rising) to cue tones in signaling word identity. Besides pitch contours, Cantonese also utilizes pitch heights (higher versus lower) in level tones to encode word meanings. In the pilot phase (60 Mandarin-speaking older adults will be recruited with data collection ongoing), participants were trained to learn Cantonese contour-level and level-level contrasts in the evening or the morning. A novel word-object identification task was used in the training, followed by three tone identification tasks: a posttest immediately after training, a 12-h delayed posttest (a trained talker), and another delayed posttest (a novel talker). Aligned with the nap study, preliminary results suggested overnight sleep might enhance seniors' tone-related memory by promoting generalization across talkers in learning contour-level contrast owing to their prior contour-tone knowledge.
Impact of noise, dysphonia, and cognitive functions on speech perception in children
Authors: Murgia Silvia , Choudhry Bisma N. , Flaherty Mary M. , Bottalico Pasquale
Published: July 2024

This study explores the detrimental effects of classroom noise and teacher dysphonia on children's speech understanding and teacher voice quality. It also investigates their impact on cognitive functions such as attention and working memory, as well as the subjective and objective measures of listening effort. Participants were 26 children aged 8–12. Results indicate that word recognition was primarily affected by the signal-to-noise ratio (SNR), with lower SNRs leading to decreased accuracy. However, listening comprehension scores were significantly influenced by both SNR and voice quality, especially when the lowest SNR combined with a dysphonic voice resulted in a significant decrease in accuracy. Higher working memory was associated with better comprehension performance. Subjective listening effort was higher when noise and dysphonia were present, with greater selective attention linked to lower perceived effort. Response times also showed that children took more time to respond in lower SNR conditions and when the speech was dysphonic, although higher selective attention led to shorter response times. In conclusion, noise primarily impacted word recognition, while dysphonia exacerbated listening comprehension. However, both factors increased perceived listening effort. These findings suggest that assessing word recognition alone may underestimate the impact of poor voice quality in noisy environments.
Acoustic signature and wake structure investigation of a cavitating marine propeller operating in proximity to a rudder with an optimized leading-edge pattern
Authors: Pendar Mohammad Reza , McIntyre Duncan , Oshkai Peter
Published: July 2024

The present study implements high-fidelity numerical modeling to investigate the cavitating flow around a marine propeller operating upstream of a rudder with an optimized wavy leading-edge (WLE), based on a NACA 634-021 profile bio-inspired by a pectoral flipper of a humpback whale (Megaptera novaeangliae). The aim of the study work is to identify the acoustic signature and wake structure of the propeller-rudder system, comparing it to that with a straight leading-edge (SLE) rudder. The propeller (INSEAN E779A model) operated under diverse marine maneuvering conditions (rudder angles of attack α = 0°, 10°, and 20°) with three distinct leading-edge patterns of the rudder. Large eddy simulations (LES) in conjunction with the Sauer cavitation method and the compressive volume of fluid (VOF) model were utilized to simulate the unsteady cavitating flow using the OpenFOAM platform. Additionally, the Ffowcs Williams–Hawkings (FW-H) acoustic analogy, continuous wavelet transform (CWT), and fast Fourier transform (FFT) were employed to predict and analyze the hydroacoustic response. We propose an optimized propeller-rudder configuration for minimizing the radiated sound levels, thus mitigating the harmful effects of noise pollution on marine ecosystems, while maintaining high propulsive efficiency over a wide range of operating conditions.
Using acoustic monitoring to evaluate the co-benefits of urban restoration
Authors: Buxton Rachel T. , Dennison Christopher , Brown Katherine , Pearson Amber L.
Published: July 2024

Restoring urban greenspaces is an increasingly common nature-based solution aiming to bolster biodiversity while benefiting human wellbeing. However, there is limited understanding of the co-benefits, including potential trade-offs and synergies between outcomes for nature and people. Although passive acoustic recording may be a valuable outcome monitoring tool, appropriate analytical techniques are unknown. We explore how different acoustic analyses capture patterns in species diversity and harmful noise pollution using 2021– 2023 acoustic data from Detroit, Michigan. Data were collected as part of a longitudinal panel study aimed at quantifying the effects of park restoration on physical activity, stress, and cardio-metabolic health. We used AudioMoth recording devices at 100 sites: 10 in the neighborhood around each of 5 restored parks, where native plants were seeded, and 10 around each of 5 unmaintained control parks, matched to restored parks based on specified conditions. Recordings were analyzed by manually identifying bird species and noise in a subset of spectrograms, using an artificial neural network (BirdNET), and using acoustic indices. We found that using acoustic indices in a model could accurately predict bird species diversity and richness, but not community composition. We compared outputs from each type of analysis with mental health indicators of study participants.
The past, present and future of underwater passive acoustic monitoring
Authors: Hildebrand John , Wiggins Sean , Baumann-Pickering Simone , Frasier Kait , Roch Marie A.
Published: July 2024

We review the history of underwater passive acoustic monitoring and predict the future trajectory. Over the past three decades, advances in digital data storage capacity and low power electronics have made it possible to collect autonomous long-term broadband passive acoustic monitoring data. Concomitant advances have taken place in data analysis and curation. Standardized spectra are an excellent first-step in analysis, calculated for all data using multiple frequency bands. These spectra allow in-situ instrument calibration based on an understanding of underwater ambient noise. Software for efficient manual scanning and signal discovery is used for verification and error estimation. Automatic detectors/classifiers are obtained from both supervised and unsupervised machine learning. Detections are aggregated into a database that allows the combination of multiple datasets and association with environmental or other data. Future work will increasing use of arrays of acoustics sensors, the integration of passive acoustics with other sensors, and machine learning that integrates these data streams to provide better understanding of anthropogenic, biological and physical processes in the ocean.
But I did science so I wouldn’t have to write essays
Authors: Stride Eleanor P.
Published: July 2024

A dislike of writing, sometimes bordering on a phobia, seems to be a common experience for many science students and indeed practising scientists. This represents a serious challenge, as regular publication is a key requirement for most areas of research. In seeking to understand the origins of this aversion, a few interesting findings have arisen. First, there are some crucial differences between technical and creative writing, but these are rarely highlighted as part of either high school or university science courses. Second, there are surprisingly few degree courses in which the scientific method is introduced and discussed explicitly. In this talk, strategies for addressing these deficiencies and taking the pain out of report and paper writing will be discussed.
Acoustical behaviour of “baroque” trumpets with vent holes
Authors: Campbell Murray , Myers Arnold , Newton Michael
Published: July 2024

The trumpets for which baroque composers including Bach and Handel wrote viruoso solo parts were natural (valveless) instruments approximately twice the length of a modern C trumpet. Playing chromatically in the high register of a natural trumpet requires great skill, since only the approximately harmonic resonances of the fixed-length air column are available. In the second half of the twentieth century several makers collaborated with performers to develop variants of the natural trumpet incorporating three or four finger-holes. Such instruments, widely used in modern ensembles playing baroque music, are best described as ‘vented trumpets’. The way in which the finger-holes are used differs from the use of tone-holes on the cornett, the keyed trumpet and the keyed bugle. In general, vented trumpets are designed to approach the timbre of natural trumpets while facilitating control of intonation and accuracy in playing. In the present paper, the acoustical foundations for the function of the three- and four hole systems are explored. The study draws on input impedance measurements, computational modelling, and playing tests of typical vented and natural trumpets. Parameters quantifying the timbre of vented trumpets are compared with corresponding values for natural trumpets.
Multirotor broadband noise modulation
Authors: Gan Ze Feng (Ted) , Tumelero Valente Vitor , Brentner Kenneth S. , Greenwood Eric
Published: July 2024

Rotor broadband noise spectra are typically analyzed over time scales on the order of one or more rotor periods. However, modulation of the broadband noise spectrum with the blade passage frequency (BPF) has been shown to be significant for noise levels and perception of wind turbines and helicopters. In contrast, time-varying broadband noise has not been extensively studied for aircraft with many rotors, such as unmanned aerial vehicles (UAVs) or advanced air mobility aircraft. In this work, significant broadband noise modulation was measured in flight and anechoic chamber tests of hexacopter UAVs at various observer angles. This modulation is aperiodic with the BPF such that the modulation amplitude varies substantially between blade passages, even when the BPFs are controlled to be nearly constant between all rotors at all times. Furthermore, the azimuthal phasing between rotors greatly affects the measured modulation, such that the modulation of multiple rotors may be less than or greater than for a single rotor, depending on the phase offsets. The effects of phase variations on acoustic interactions between rotors is studied by comparing the sum of the modulation of individual rotors to the modulation of those rotors operating simultaneously. This is done not only using measurements, but also noise predictions made using PSU-WOPWOP. These results contribute understanding to how the noise modulation of rotors sum together, including the resulting directivity and aperiodicity.
Soundscape techniques applied to urban planning goals
Authors: Brooks Bennett M. , Schulte-Fortkamp Brigitte
Published: July 2024

The soundscape method is a powerful tool for understanding the perception of our acoustical environment. Urban planning is the technical and political process by which we manage and mold our cities. Smart growth is a movement within urban planning which emphasizes the livability of our surroundings. These disciplines all seek to shape the form of our communities to improve the quality of life for those who live, work, and play there. Yet, there has been little formal interaction between soundscaping and urban planning. It is imperative that soundscapers who wish to implement improved urban designs and interventions adopt the language and methods of urban planners in order to succeed and accomplish their mutual goals. Soundscape protocols must engage the urban planning process, including the comprehensive, or master, plan to achieve implementation on a city-wide scale. Several recent initiatives which illustrate the integration of soundscape techniques with urban planning methods are presented and discussed.
Predicting infrasonic wind noise levels using local topographic features
Authors: Frazier Garth , Waxler Roger M. , Hetzer Claus
Published: July 2024

This presentation describes a method for predicting RMS wind noise levels within a user-specified infrasonic frequency band (e.g., 1–10 Hz) using local topographic features. This capability is especially valuable when performing site selection for infrasound sensor array deployment. The method is based on building models using measured infrasound data from known sensor site locations and the local topographic features corresponding to the site. The presented results correspond to using features such relative terrain elevation and relative vegetation height obtained from publicly available sources. Mean wind speed and direction are also included as predictive parameters and these can be from data measured at the infrasound sensor site or from estimates obtained from a tool such as the Weather Research Forecast (WRF) model as was utilized for this investigation. A novel feature of the approach is that the terrain specification is not uniquely site specific but also depends on wind direction. Essentially, the topographic features are specified relative to wind direction and not in absolute coordinates. This enables a much richer set of samples from which to build the predictive models. While many options are potentially available for model building, this work focused on the use of multiple-layer artificial neural networks as a basis for regression. The results presented correspond to data from several infrasound sensor sites in the U.S Array Project.
Planes, trains, and automobiles: Three case studies of building envelope design addressing transportation noise
Authors: Clements Jessica S. , Garretson John , Barringer-Cook Kirsten
Published: July 2024

This presentation will focus on three case studies of designs to limit transportation noise through the building shell to support the successful use of the building. The first project focuses on an office building located close to beautiful water views that desired a building shell made primarily of glass. However, it will be located directly under the flight path of a nearby US Airforce base. The second project considers a hotel conference center located directly adjacent to a heavy rail line. The third project address movie sound stages located adjacent to a major highway and directly under the flight path of Hartsfield Jackson International Airport, known as the busiest airport in the world. Site measurements were taken for each of these locations and a detailed review of the data used to determine which noise sources and frequencies of concern would be the focus of the design. The presentation will present examples of the collected data, the design strategies used, and discuss the challenges faced by the design team.
Acoustic monitoring of harbor porpoises in Hood Canal, WA: Efforts to improve detection of a highly cryptic cetacean
Authors: Ghoul Bergman Asila , Grebner Dawn
Published: July 2024

Harbor porpoises (Phocoena phocoena) are the smallest, most abundant cetaceans occurring within the waters of the US Navy’s Northwest Training and Testing Ranges. The ability to detect harbor porpoise and monitor their presence over time is essential to assessing potential impacts of Navy activities. This can be difficult due to their highly cryptic nature exhibited in their surface behavior (vessel avoidance) and acoustic repertoire (producing only high-frequency clicks). This presents significant challenges for both visual and acoustic (PAM) survey methods. Here, we discuss the Navy’s efforts to improve harbor porpoise monitoring capability using an automated acoustic detection system. We tested multiple detection algorithms and evaluated their performance in identifying and extracting harbor porpoise clicks from acoustic recordings collected in Hood Canal, WA. Using this detection data combined with data collected from concurrent visual surveys of Hood Canal, we explored how acoustic and visual methods may be used in concert to improve harbor porpoise monitoring. Hood Canal provides a unique opportunity to do this, as it is the only known US Navy range with a resident population of harbor porpoise. These efforts will also inform future behavioral response studies needed to measure the impact of Navy sounds to individual animals.
Possible physical mechanisms of the high echogenicity of lipid coated nanobubbles
Authors: Jafarisojahrood Amin , Exner Agata A. , Kolios Michael , Goertz David
Published: July 2024

Lipid coated nanobubbles (NBs) have attracted a great level of interest as ultrasound (US) contrast agents due to their ability to extravagate through leaky tumor vasculature. Their linear resonance frequency is in the range of ∼50 M Hz–200 MHz, leading to confusion over their observed strong contrast in diagnostic US frequencies. By solving the Marmottant model, the dynamics of uncoated and lipid coated NBs and microbubbles (MBs) are studied over the frequency and pressure ranges (6–12 MHz, 0.1–1.2 MPa) generally used in diagnostic US. A novel bifurcation analysis in tandem with the analysis of the frequency component of the scattered pressure are conducted. Results show that despite the increased linear resonance frequency and viscous damping due to the lipid shell, buckling and rupture of the shell enhances the generation of the 2nd and 3rd harmonic resonances at pressures as low as 0.2 MPa, not observed with uncoated NBs. The generation of the harmonic resonances are concomitant with an abrupt increase in the 2nd and 3rd harmonic frequency component of the scattered pressure with their pressure threshold (PT) increasing with decreasing NBs size. For the same gas volume, and above the PT, the maximum non-destructive 2nd and 3rd harmonic powers of NBs can become higher than the 2–4 μm MBs. Similar to the lower subharmonic pressure threshold of MBs, the dynamic variation of the NBs effective surface tension due to buckling and rupture may be the potential reason behind the observed harmonic echogenicity.