bluuebunny/crossref_metadata_2025 huggingface dataset:
Recital Hall into existing structure limited height space
Authors: Manley David , Pippitt Logan
Published: November 2022

Renovations for a college Fine Arts program desired to reincorporate multiple art departments that had become scattered over various locations throughout campus into an existing mid-century architecture legacy building. Included in the renovation program is a 130 seat Recital Hall, Instrumental Music Labs, and Commercial Music Recording program. The particular small rooms challenge presented is that the 130 seat Recital Hall must fit within an existing concrete waffle slab structure with a height of 17 feet from floor to bottom of structure and a total room volume of only 30,000 cubic feet. This presentation will walk through the challenges of providing an acceptable room acoustic environment for recitals amongst the other design challenges of ADA accessibility, sound separation to other arts programs, modern MEP services and requirements, and limitations of existing structural capacity.
Adjustable acoustics for imperfect rooms
Authors: Lenz Richard L.
Published: November 2022

Very often, acousticians are faced with room dimensions that are fixed and cannot be adjusted. This dilemma is exascerbated when the room is to be used for purposes of music performance. It is further complicated when the goal of the room is to present a broad spectrum of music types from classical symphony to modern jazz or rock. An example will be presented of an essentially square room space that was designed and treated to be adaptable to meet the requirements of all types of performances. Tabor College in Hillsboro, KS had space on its campus to build one concert that had to serve all of its performance needs. The physical space available, in order to maximize the size of the hall, also turned out to be a nearly perfect square in the audience area. Tom Ryan of The Hallani Group, working with the author and RealAcoustix, designed an acoustical system that allows the room to perform well for all types of music performances while being easy to change and architecturally beautiful. The design criteria, auralizations, and other information will be presented showing how this was accomplished.
Small band rooms for large bands: Balancing loudness and musicality
Authors: Brill Laura C. , Giegold Carl P.
Published: November 2022

When band rooms are smaller than ideal for the ensembles they support, there are safety concerns due to loudness. In the case study presented, students have experienced excessive loudness and difficult ensemble conditions due to inadequate ceiling height, absorption, and volume. This paper will discuss the strategies explored to increase acoustic volume to the extent possible within floorplate boundaries while finishing the space with a combination of absorption and diffusion. The goal of these interventions is to preserve ensemble and a sense of musicality to assure students and faculty they are working in a space designed for music rather than simply the control of loudness.
Two case studies in approach to the renovation of volumetrically challenged music rehearsal spaces
Authors: Hunt Kaitlyn , Shou Anthony
Published: November 2022

A music rehearsal room renovation can be acoustically challenging in that there is often limited room volume, lack of loudness control, and budget constraints. Two case studies detail these challenges. (1) The University of North Texas’ choral rehearsal room was due for renovation and with a volume of only 44,000 cubic feet, the room had to accommodate choral ensembles varying from 20–85 people for daily use, over 100 voices for an annual festival, and an added recital use. At an appropriate budget, the renovation used room shaping to simultaneously break up parallel surfaces and support voices while also adding adjustable acoustics to allow for tuning of the room for each rehearsal or performance. (2) The University of Texas at San Antonio’s large band, orchestra, and jazz rehearsal room lacked loudness control even with an approximate volume of 73,500 cubic feet to serve 30 – 70 + musicians. At a much more limited budget, the solution was to flip the orientation of the musician layout in the room to take advantage of the existing room geometry and to introduce variable absorption stored exposed to the room which increased the overall absorption while also giving the ensembles an opportunity to tune the room.
Undersized music ensemble rooms: Challenges and case study design approaches
Authors: Markham Benjamin E.
Published: November 2022

Music ensemble rooms require sufficient volume to develop adequate and appropriate reverberation, facilitate ensemble balance, and avoid excess loudness. Typical design practice begins with establishing minimum volume requirements based on expected ensemble sizes and types. When faced with inadequate room volume (e.g., due to existing building limitations, or otherwise), creative design solutions must be employed to achieve the best possible hearing conditions—and to avoid excess loudness in particular, which can be an occupational hazard for musicians. Case studies will illustrate a variety of design approaches: adding volume to existing spaces at the Crane School of Music (SUNY Potsdam), electronic reverberation enhancement (also at Crane), adding absorptive materials to an existing space and master-planning for larger spaces at Arkansas Tech, creative diffusive and absorptive material for the chorus rehearsal room at Boston Symphony Hall, and programming work to match ensembles to the most appropriate rooms available at a variety of educational institutions.
Loudness control in a small volume Recital Hall
Authors: Yau Justin , Corry Brian
Published: November 2022

Mississippi State University’s new music building features a 173-seat Lecture Hall that also serves as a recital hall. The limited volume presents an acoustical challenge to accommodate a variety of uses—most concerning are the louder and larger ensembles with up to 25 musicians and 50 singers sharing the stage. Due to project-specific constraints, the 24 foot stage-to-ceiling height and the 60,000 cubic foot volume are less than the early design-phase recommendations for the expected uses, which raises concerns about loudness buildup and inability to generate desired reverberation. Our goal is to implement variable loudness control systems that provide a useful reverberation range with good clarity across different settings. We identify and justify four loudness control strategies—maintain early, supportive reflections; shape the room to form patterns of sustained sound in areas with adjustable absorption; reduce high-frequency sustain in areas near audiences; avoid flutter echoes—and illustrate how those strategies were integrated into the architectural design through room shaping, fixed wall treatments, and deployable curtains and banners. We discuss subjective and instrumented observations about the loudness (measured in Sound Strength G), reverberation time (measured in T30), clarity (measured in Clarity Index C80), and overall character of the room response.
Mapping the intersection of helicopter routes and public lands in Northeast Scotland
Authors: Wolek Nathan
Published: November 2022

During the various COVID lockdowns, public narratives about the changing soundscape emphasized the reduction in commercial air traffic. However, other forms of air traffic were not reduced. Due to the need to service North Sea oil and gas operations, helicopter overflights from Aberdeen Airport (ABZ) remained a prominent feature of the local soundscape in Northeast Scotland. The primary route used by these helicopters (HMR WHISKEY) crosses public lands at several points, making the sound of overflights a prominent source of noise at these locations. These public lands include locations controlled by the city, like Seaton Park and Donmouth Local Nature Reserve, and others controlled by national entities, like the Forvie National Nature Reserve. This presentation will map several public lands in Northeast Scotland where noise from frequent helicopter overflights impacts the soundscape. The author will present field recordings and other documentation of helicopter overflights from February to June 2021, both during and immediately after the United Kingdom's third COVID lockdown, and invite discussion about potential for further study of noise pollution in this coastal region.
MonitorMyOcean.com: Measuring the acoustic impact of the COVID-19 lockdown on underwater ocean noise
Authors: Nath Artash
Published: November 2022

Low-frequency noise from marine shipping is an underwater acoustic pollutant. The noise spectrum overlaps with frequencies marine mammals use to communicate, leading to stress and behavioural disruptions. This research established a model to measure the effects of anthropogenic activities on underwater noise. The COVID-19 lockdown led to a decline in marine traffic. The model quantified the reduction in noise levels before and during the lockdown in the Arctic, Atlantic, Pacific Oceans, and the Mediterranean Sea. Underwater ocean sound peaks between 10 and 100 Hz and is dominated by noise from shipping traffic. Hydrophones data from seven ocean observatories were analyzed at 1-Hz spectral and 1-minute temporal resolution. Power spectral densities were calculated, aggregated into monthly long-term spectral averages, and noise levels in the 63 Hz third-octave band were compared. The analysis revealed that global oceans quietened by an average of 4.5 dB during the lockdown period. The maximum decrease was at locations close to major shipping channels and cruise tourism destinations. The study proved that strategic “anthropauses” could reduce underwater noise levels. A web application MonitorMyOcean.com endorsed as a UN Ocean Decade Activity, was created to provide updated anthropogenic ocean noise levels.
Shelfbreak processes affecting acoustic propagation in a changing ocean
Authors: Gawarkiewicz Glen
Published: November 2022

Fundamental physical oceanographic processes affecting sound speed fields and acoustic propagation have been studied in shelfbreak regions for some time. Integrated observations extending back to the 1990s have related acoustic propagation variability to basic thermohaline structure as well as physical oceanographic processes causing significant variability in sound speed fields. Key shelfbreak processes such as frontal wave propagation, eddy-Shelfbreak Jet interactions, and wind-driven motions will be described. The influence of ocean warming and climate change impacts on these processes will be outlined with emphasis on the Middle Atlantic Bight in the northeastern United States. The impacts of changes in both the atmospheric Jet Stream as well as the Gulf Stream on the Shelfbreak Front and Jet and implications for acoustic propagation will be presented.
High resolution mapping of sound speed and density with broadband echo sounders
Authors: Loranger Scott , DeCourcy Brendan J. , Lin Ying-Tsong , Lavery Andone C.
Published: November 2022

Advances in acoustic propagation and physical oceanographic modeling necessitate improved spatiotemporal resolution of water column properties (temperature, salinity, sound speed, and density) to inform and validate models. Shipboard profiling provides adequate vertical resolution, but high-resolution horizontal sampling is expensive and time consuming. Stationary arrays generate critical long-term data sets and high vertical resolution, however, there is a trade-off between dense horizontal sampling and total spatial coverage. Towed systems provide dense coverage horizontally but lack vertical resolution in a single location. During the ONR funded New England Shelf Break Acoustics experiments in 2021, sparse shipboard CTD and expendable bathythermograph (XBT) casts were combined with backscatter measurements by shipboard broadband echo sounders to map water column physical properties of the New England Shelf Break front with high resolution vertically and horizontally. The shipboard echo sounders detected backscatter from the strong gradients of the shelf break front, physical microstructure, and internal waves present at the frontal boundary. Acoustically tracking the front between CTD casts resulted in high resolution profiles of water column properties. Acoustic propagation modeling at 500 Hz and 4 kHz was compared when using the acoustically determined water column profile and when using profiles from CTD and XBT casts alone.
Paul Langevin the Scientist
Authors: Catheline Stefan
Published: November 2022

“Summarizing Paul Langevin’s work implies revising the whole history of physics (…), this is a difficult but exciting task” Louis de Broglie said during Langevin’s funeral. Paul Langevin was a universal mind, and he had worked in all branches of physics: gaseous ions, Brownian motion, electromagnetism, dia and para magnetism, birefringence, special relativity, ultrasonic waves, and neutron collisions. Very rare are those who can pretend to such a scientific impact. Yet at the same time, during a time span that included two world wars, Paul Langevin directed an engineering school ESPCI (Ecole Supérieure de Physique et Chimie Industrielle), gave courses at collège de France, ENS (Ecole Normale Supérieure), and was actively involved in the Solvay Conferences that he organized when Hendrick Lorentz passed away. The last part of the presentation is devoted to the present Paul Langevin legacy. As illustrations, a membrane wave experiment that revisits the 1919 Eddington observation of Albert Einstein prediction is followed by a walking liquid droplet set-up by Yves Couder. Open questions about the unfinished work that Paul Langevin and his scientific Solvay group left us will conclude this presentation.
Langevin’s ultrasonics
Authors: Duck Francis
Published: November 2022

Langevin’s work in ultrasonics, which resulted in about twenty publications and patents, will be reviewed. At the beginning of WWI, encouraged by Marie Curie, he started work on a directional ultrasonic system to detect submarines and for underwater communications, based on Chilowski’s proposal. Rejecting whistles, sirens and magnetic sources, he used a large mica ‘singing’ condenser for transmission, and proposed a large area carbon granule microphone as receiver. Noise problems with carbon receivers led Langevin, in early 1917, to test a single large slice of quartz, cut perpendicularly to one of its three electrical axes. This orientation differed from that used by Jacques and Pierre Curie’s quartz piezo-électrique, in which the stress and electrical axes are perpendicular. Later that year he demonstrated quartz as a transmitter, creating the enabling technology for later ultrasonic developments. The knowledge was freely disseminated to other Allied laboratories. After the war, Langevin gave the first ever course on theoretical and practical ultrasonics. He facilitated the technological transfer of pulse-echo technology from military to civil sectors and the establishment of a laboratory in Toulon for the certification of ultrasonic transducers. His co-workers went on to study magneto-strictive and high-frequency quartz transducers, therapeutic applications, and finite-amplitude propagation.
Langevin’s contributions to pulse echo piezoelectric transducers
Authors: Szabo Thomas L.
Published: November 2022

Paul Langevin made fundamental discoveries which laid the foundations of modern pulse echo ultrasound over a hundred years ago. He was the first to employ piezoelectric crystals, X-cut quartz, with the propagation and electric axes aligned. In his design, the crystal thickness was a half-wavelength longitudinal wave resonator for both a transmitter and receiver which is the most popular configuration in use today. He invented the Langevin transducer which added two quarter wave layers on either side of the piezoelectric crystal to increase overall efficiency. A mosaic pattern embodied smaller pieces of scarce quartz. His original designs will be demonstrated through simulator models. By selecting ultrasound frequency of 40 KHz, he was able to make more directive beams and extend range for pulse echo detection. By adding triode amplifiers, the sensitivity of reception was increased greatly, and transmission powers of a kilowatt were achieved. With special circuits for making short pulses, long range, high resolution pulse echo ranging became a practical reality. Langevin’s innovations led to sonar and eventually to ultrasound imaging.
Paul A. Langevin’s contributions to nonlinear acoustics
Authors: Hamilton Mark F.
Published: November 2022

Paul A. Langevin made several important contributions to nonlinear acoustics, but our knowledge of these contributions is mainly due to accounts given by others, most notably Biquard (Ann. Phys., 1936). At the end of Chapter 1 in Nonlinear Acoustics (ASA, 2008), Blackstock summarizes Biquard’s account, which is in turn based on lectures delivered by Langevin at the Collège de France in 1923. Langevin derived the coefficient of nonlinearity for liquids, predating the quantity subsequently expressed as β = 1 + B/2A, and provided measured values for several liquids. He also obtained an expression for the profile of a steady shock wave and described its subsequent decay, predating the classical Fay solution published in 1931. However, Langevin is most well known in nonlinear acoustics for a quantity that bears his name, the Langevin radiation pressure, and for what distinguishes it from the Rayleigh radiation pressure [Beyer (JASA, 1978)]. Rayleigh’s result applies to a constrained field such as a standing wave in a closed tube, and it depends on the nonlinearity parameter B/A, whereas Langevin’s result applies to an unconstrained field such as a sound beam, which is more common in practice, and it is independent of B/A.
A raceway’s outdoor concerts get shut down by new residents
Authors: Taubitz Sarah
Published: November 2022

An existing raceway near a state highway desired to add concerts to its schedule. The oval racetrack (cars, motorcycles, etc.) has been in the community for decades, and more recently houses have been built within 700 feet. 45dB Acoustics acoustically modeled the concert situation, reporting that sound levels from concerts would be not unlike those from existing racetrack events. Nearby residents had signed their acknowledgement of potential noise from the racetrack, but some complained to the County about live music being “a new project and not an approved use of the facility.” A Commercial Outdoor Entertainment License application was then required and granted by County Board of Supervisors, which included a public hearing at which the author was present to answer any Board questions. Although the License was granted, COVID put everything on hold, and some residents filed a lawsuit citing that the Board improperly granted an exemption of an Environmental Impact Review and California Environmental Quality Act review. After COVID restrictions lifted, the Board required the applicant to repeat the application process. Raceway ownership has not only abandoned the concerts, but also completely shut down the business, citing legal and consultant fees.
A game theory model of the Lombard effect in public spaces
Authors: Boren Braxton
Published: November 2022

The Lombard effect is the tendency for humans and other animals to raise their vocal intensity in the presence of background noise. As a result, the aggregate effect of many people talking in a public space can lead to multiple equilibria for speech intelligibility, as the incentive for an individual conversation is dependent on the actions of all the other speakers in the space. This system is modeled using game theory, in particular, an n-person Prisoner’s Dilemma model, otherwise known as the Unscrupulous Diner’s Dilemma. It is suggested that conscious knowledge of the dynamics of the system can affect the system's behavior up to a point, but that gradually the subconscious process of the Lombard Effect will cause the system to increase in background noise, only limited by the comfort of each speaker’s voice or an exogenous interrupting event.
Acoustic radiation torque on an interface reflecting acoustic vortex beams
Authors: Zhang Likun
Published: November 2022

Torque exerted by acoustic waves to rotate objects can result from asymmetry such as the case of an averaged torque on a Rayleigh disk exerted by an ordinary acoustic field. In the absence of asymmetry, acoustic torque can occur by viscous absorption either in the object or in the adjacent boundary layer of the object when using specific types of acoustic fields such as acoustic vortex beams carrying twisted wave fronts [Zhang and Marston, Phys. Rev. E 84, 065601 (2011)] or two orthogonal standing wave fields [Zhang and Marston, J. Acoust. Soc. Am. 136, 2917 (2014)]. Recent study suggested a torque on a flat water-air interface exerted by an ultrasonic vortex beam obliquely incident and reflecting off the interface [Zou, Lirette, and Zhang, Phys. Rev. Lett. 125, 074301 (2020)]. This torque is not associated with viscous absorption and instead results from variation of orbital angular momentum carried by the vortex beam during the reflection. The torque would otherwise disappear in normal incidence or using ordinary beams. The investigations advance understanding of radiation torque physics and approaches for non-contact manipulations using acoustic waves.
Acoustic streaming in a channel
Authors: Thompson Charles , Denis Max , Chandra Kavitha
Published: November 2022

This paper presents an analysis of acoustic streaming in a 2D channel. The unsteady flow resulting from acoustic excitation of the enclosed fluid is of particular interest. The magnitude of the streaming velocity will depend on the Strouhal, S, and oscillatory Reynolds numbers, R. For the frequencies of interest, 1/R and 1/S are much less than one. Results are given for the streaming Reynolds number R/S2 = O(1). Pressure correction approaches used to satisfy the no-slip boundary condition are explored.
Using motile cells to characterize surface acoustic wave-based acoustofluidic devices
Authors: Narayan Advaith , Cui Mingyang , Meacham J. Mark
Published: November 2022

Acoustic microfluidics is a robust and powerful method to manipulate cells and cell-like particles on chip, having good biocompatibility and ease of incorporation into multioperation microfluidic devices compared to optical manipulation. However, the use of acoustic microfluidics is largely confined to research settings. The primary barrier to translation of this technology toward clinical and industrial uses is the inability to experimentally determine the pressure field (shape and amplitude) and associated acoustophoretic forces in real time as device conditions vary. Despite the multitude of previous characterization methods, none provide the flexibility of motile cells (e.g., the unicellular alga Chlamydomonas reinhardtii) as probes to map evolving pressure fields on chip. We have previously developed this approach for use with bulk acoustic wave (BAW)-based devices. Here, we extend the method to qualitatively assess device resonances and relative field strengths for surface acoustic wave (SAW)-based devices with straight channels and circular chambers driven at 6 MHz and 20 MHz. The fabrication and electrical characterization of hybrid BAW/SAW devices with glass channels are also discussed. Upon testing, the optimal device operating parameters are identified using impedance measurements, as well as visual identification of resonant frequencies using the swimming algae cells.
Sensitivity of acoustic parameters on the reflected signal from a rigid porous medium in the low-frequency range of ultrasound
Authors: Sadouki Mustapha , Mahiou Abdelmadjid , Souna Nacera
Published: November 2022

Porous materials are two-phase media consisting of pores saturated with a fluid emerging from a solid skeleton. There are several parameters describing the porous medium. These parameters are classified into two categories: the high-frequency parameters and the low-frequency parameters. During the excitation by an acoustic wave, two cases can occur; the vibration of both phases simultaneously in the case where the structure is flexible, this case is well studied by Biot theory. For a rigid structure, it is the movement of the fluid that is taken into account; this last case is treated by the equivalent fluid theory which is a particular case of Biot theory. Previous work [Proc. Mtgs. Acoust. 45, 045004 (2021)] has shown the influence of the parameters involved in the corrected Johnson-Allard model recently introduced by Sadouki [Phys. Fluids 33, (2021)] on the transmitted signal from a rigid-porous material in the low-frequency regime of ultrasound. The objective of this work is to show, once again, the influence of the same parameters on the reflected signal by providing a comparative study between transmitted and reflected modes.
Acoustic erythrocytometer for mechanical cell probing
Authors: Link Andreas , Franke Thomas
Published: November 2022

The mechanical properties of cells provide key insights into the type, differentiation and/or pathology of a cell. The mechanical analysis of a cell population, such as a blood sample, enables meaningful biological and medical interpretation for the diagnosis and monitoring of diseases. There are number of diseases, which alter the mechanical properties of human red blood cells (RBCs). Here, an acoustic method to probe both the viscous and elastic mechanics of single RBCs by SAW in a microfluidic device is presented. The device operates by exciting a surface acoustic wave in a microfluidic channel creating a stationary acoustic wave field of nodes and antinodes. RBCs are attracted to the nodes and are deformed. Using a stepwise increasing and periodically oscillating acoustic field, the static and dynamic deformation of individual red blood cells one by one was studied and the deformation by the Taylor deformation index D and relaxation times were quantified. The precision of the measurement allows to distinguish between individual cells in the suspension and provides a quantitative viscoelastic fingerprint of the blood sample with a resolution of a single cell. The method overcomes limitations of other techniques that provide averaged values and has the potential for high-throughput screening.
Digitally tunable non-reciprocal wave propagation using piezoelectric metamaterials with synthetic impedance circuits
Authors: Alshaqaq Mustafa , Sugino Christopher , Erturk Alper
Published: November 2022

One common approach to enable non-reciprocal wave propagation in elastic media relies on introducing a directional bias by parameter modulation (e.g., stiffness modulation) in space and time. Researchers have successfully demonstrated non-reciprocal wave propagation by coupling elastic waveguides with magnetic electrical coil elements, piezoelectric elements shunted to capacitive analog circuits, or rotating mechanical resonators. The existing efforts are often limited by narrow operation frequency ranges and cumbersome implementations that lack smooth modulation (e.g., with analog circuit elements and switches). In this work, we demonstrate precise and smooth non-reciprocal wave propagation in a piezoelectric metamaterial by connecting each unit cell to a digitally controlled synthetic impedance circuit. The effective impedance of each unit cell can be externally controlled according to a desired space-time modulation scheme over a wide frequency range. We present numerical and experimental investigations on the dynamics of a piezoelectric metamaterial beam with 30 bimorph unit cells whose impedances can be varied smoothly. Specifically, we employ the spatiotemporal modulation on synthetic inductance circuits rather than capacitive. Experimental results are presented for various space-time modulation profiles, investigating the effects of the inductance value (target frequency), as well as the modulation frequency and amplitude on digitally tunable non-reciprocal wave propagation.
Exploration of tunable properties of a one-dimensional leaky-wave antenna
Authors: Willson Abigail D. , Wixom Andrew S. , Hanford Amanda
Published: November 2022

Leaky-wave antennas (LWA) are commonly used in beam-steering situations such as radars, imaging, and other such frequency scanning applications. LWA are particularly useful metamaterials due to their relatively simple structure of repeated cells in a linear array and their broad scanning range allowing for more use to come from a single frequency sweep. Among current methods to model and design acoustic LWA are notably high fidelity models such as finite element analysis and low fidelity models such as the acoustic transmission-line equations. Presented is a technique for a mid-fidelity model of a one-dimensional acoustic LWA using a lumped element system. This model is used to explore rapid evaluations of different tuning options in the elastic membranes separating the unit cells of the structure. Comparisons are made between time and frequency domains as well as modal and physical space simulations.
Imaging sonar performance estimation
Authors: O'Donnell Brian , Pate David J. , Cook Daniel
Published: November 2022

Imaging sonar systems including forward looking sonars, synthetic aperture sonars, and real aperture sonars produce large quantities of data and are often connected to automated target recognition (ATR) algorithms. Performance of these algorithms degrades, sometimes significantly, with changes in environmental reverberation, seafloor sediment characteristics, and target characteristics. However, most ATR algorithms have no capability to assess their own performance, flag data that is invalid, or convey when their results should not be trusted or utilized by humans or autonomous algorithms. Performance estimation algorithms can be used in conjunction with ATR to supplement these shortcomings. Estimates of signal-to-noise ratio, image contrast, and resolution can be used to assess deviation from nominal performance capabilities, while regressing ATR performance against imagery characteristics or other through-the-sensor metrics can be used to estimate false alarm rate.
The challenge and solutions to providing consistent masking sound levels in individual rooms
Authors: Koukounian Viken
Published: November 2022

The propagation of sound in the built environment—impacted by size and geometry of a space, finishings, furnishings, and fit-outs—is exceptionally complex. It is for this reason that experts in acoustics need to consider all features of all spaces, despite the availability of prescriptive tools—e.g., categorization, acceptable-level and reverberation time [design] schemes—which are insufficient towards assuring any acoustical outcome. The use of a sound masking system is one acoustical solution that can be used to meet acoustical objectives, such as acoustical comfort and speech privacy, by reducing the variability in temporal, spectral, and spatial properties of sound within a space. The following investigation utilizes commissioning data of sound masking systems to underline the need for dedicated control zones for individual rooms. More specifically, the overall and one-third octave band levels of masking sound in rooms within the same control zone are compared against the project’s specifications (i.e., the target overall level and the reference masking spectrum). These results enforce opportunities to improve the performance of a sound masking system to realize more consistent perceptual (i.e., acoustical comfort and speech privacy) outcome.
Wave acoustic solutions in small rooms
Authors: D'Antonio Peter
Published: November 2022

This presentation will discuss the growing application of wave based solutions due to the increased processing power of desktop and distributed cloud cluster computing. The causes and mitigation of four types of potential acoustical distortion in small rooms, below and above 200 Hz, will be presented. Below 200 Hz, approaches to minimize modal effects and the speaker boundary interference response will be presented. We will discuss limitations of traditional dimensional ratio determinations, more accurate wave-based predictions, importance of speaker and listener locations, and prediction and measurement of low frequency absorption devices. Above 200 Hz, comb filtering from strong specular reflections and poor diffusion are potential problems. We will describe the necessary ratio of surface width to incident wavelength for a specular reflection and its effect on comb filtering. Finally, we describe the importance of creating a mixing room design and the use of broad bandwidth diffusive surfaces, which can be both measured and simulated with a virtual goniometer boundary element program called VIRGO, from a 3D CAD file topology of any shape. This offers the acoustician the ability to evaluate surface topologies that are of interest in a room design quickly and inexpensively.
Coupled effects of nonlinear internal gravity waves and seabed properties on underwater sound propagation
Authors: Chen Tzu-Ting , Lin Ying-Tsong , Chiu Linus Y.-S. , Siegmann William L.
Published: November 2022

Underwater sound propagation can be affected by strong sound speed gradients induced by nonlinear internal waves in the ocean. Meanwhile, geoacoustic properties of the seabed control acoustic reflections. Experimental data collected at the shelfbreak on the northeast of the South China Sea were analyzed to investigate the joint effects. Both two-dimensional (2D) and three-dimensional (3D) numerical sound propagation models with realistic seafloor and oceanographic inputs have been established to study the nonlinear internal wave effects observed on hydrophone vertical line array moorings. Compared to the 3D model, the prediction errors and uncertainties of the 2D scheme neglecting the transversal/azimuth energy propagation are discussed. In addition, the impact of sediment properties on 3D propagation effects affecting underwater soundscapes in the area is investigated. [Work supported by the Office of Naval Research.]
Twenty-first century outer continental shelf and shelfbreak acoustics research: Methods, tools, and progress
Authors: Duda Timothy F. , Newhall Arthur E. , Lin Ying-Tsong , Lynch James , Gawarkiewicz Glen , Zhang Weifeng G. , Helfrich Karl R. , Lermusiaux Pierre F. , von der Heydt Keith , Kemp John
Published: November 2022

New findings in outer-shelf and shelfbreak acoustics have been enabled by experimental and computational advances over the last 25 years. The details of sound field variability caused by highly dynamic conditions often found in this regime have become measurable through advances in data collection technology. Furthermore, these details can now be computationally modeled more realistically. The coupling of more plentiful data and higher fidelity modeling has uncovered many new behaviors. It has also allowed us to quantify the effects on sound level and phase structure (coherence) of many outer-shelf physical features, as well as the temporal aspects of these variations. Key tools have been vessel dynamic positioning, underwater position finding, small mobile platforms, high-capacity multichannel receive arrays, data-assimilating regional ocean dynamical models, nonlinear wave modeling, and three-dimensional acoustic propagation modeling. Examples from the published work of the authors, and the work of others, of how these advances have fostered new knowledge of specific processes will be presented, as well as present-day challenges inspired by recent findings.
Influence of the vertical resolution when simulating ocean sound speed variability in mesoscale eddies
Authors: Touret Richard X. , Liu Guangpeng , Bracco Annalisa , Sabra Karim G.
Published: November 2022

Vertical resolution affects the representation of ocean sound speed according to a suite of regional simulations of the De Soto Canyon circulation in the Gulf of Mexico. Simulations have identical horizontal resolution of 0.5 km, partially resolving submesoscale dynamics, and increasing vertical resolution from 30 (i.e., comparable to what commonly used in mesoscale permitting or resolving hindcast and forecast products such as HYCOM) to 200 terrain-following layers. Simulations with 30- and 70-layers underestimate the ageostrophic contributions in and around the eddies below the mixed-layer and do not reproduce the sharp vorticity and density variations associated with the mesoscale circulations compared to the 140- and 200-layers runs. The ocean sound speed (based on the classical MacKenzie formula) was found to be far more variable when the submesoscale, ageostrophic circulations are captured also in their vertical structure and vertical contributions to the density field. Hence, the results of this study indicate that to better predict the influence of the submesocale oceanic circulation on ocean sound speed variability, model simulations should consider enhancing both horizontal and vertical resolution to resolve at least the first 3 baroclinic modes. To do so, more than 100 vertical layers were found to be needed in this study.
Surface excitation of focused shear wave beams in soft elastic media: Theory
Authors: Archer Branch T. , Chao Yu-Hsuan , Cormack John M. , Kim Kang , Spratt Kyle S. , Hamilton Mark F.
Published: November 2022

Shear wave propagation is employed in medical ultrasound imaging, because it reveals variation in the viscoelastic properties of tissue. Frequencies below 1 kHz are required for imaging with shear waves in soft tissue due to their high attenuation and low propagation speeds, compared to compressional waves with frequencies above 1 MHz used for ultrasound imaging. Shear waves exhibiting particle motion in the direction of propagation, referred to as longitudinally polarized shear waves, can be generated by applying longitudinal motion of a circular disk to the surface of a soft elastic medium. This approach is used in practice because it permits imaging of the longitudinal shear wave with a conventional ultrasound transducer that is coaxial with the source of the shear wave. Presented here are the theoretical framework and numerical simulations that illustrate effects of focusing on longitudinally polarized shear waves. Longitudinal, transverse, radial, and torsional source polarizations are considered. The present investigation was motivated initially by an experimental study in optics due to Dorn et al. [Phys. Rev. Lett. 91, 233901 (2003)]. Our predictions for shear wave beams support their measurements of light beams revealing that the longitudinal electric field component produces a smaller focal spot than the transverse field component.
Comparison of arterial mechanical properties measured with arterial dispersion ultrasound vibrometry and clinical arterial stiffness metrics
Authors: Urban Matthew W. , Lee Hyungkyi , Roy Tuhin , Capron Charles , Lopez-Jimenez Francisco , Hesley Gina , Aquino Wilkins , Guddati Murthy , Greenleaf James
Published: November 2022

Arterial stiffness is recognized as a highly clinically relevant and independent prognostic biomarker of cardiovascular disease. Arterial dispersion ultrasound vibrometry (ADUV) uses acoustic radiation force to generate propagating waves in the arterial wall and measures the wave motion to estimate arterial mechanical properties from fitting phase velocity dispersion curves to a waveguide model. ADUV measurements were made with a Verasonics V1 system with a L7-4 linear array transducer in 63 human subjects (27 male/36 female) from ages 50–88 years old. We made measurements at 10 time points within the cardiac cycle, termed cardiac stages. We estimated the phase velocity (median of cp from 400-600 Hz) and G determined from matching the dispersion curves with those from a waveguide model incorporating the artery diameter and wall thickness. Within the same study visit, we measured the intima-media thickness and diameter changes through the cardiac cycle with a General Electric Logiq E9 or E10 scanner. We also tonometry to determine the carotid-femoral pulse wave velocity. We report here comparisons of median phase velocity, cp, and inverted shear modulus, G, at different stages of the cardiac cycle with clinical metrics of arterial stiffness.
A heat balance model to explain thresholds for thermoacoustic sound production in seawater using metal electrodes
Authors: McBeth Michael S.
Published: November 2022

Experiments conducted with solid metal wire electrodes in seawater generated second harmonic sound waves thought to be thermoacoustic in origin. Using sine wave bursts of three to twenty-five cycles of 10 kHz voltage across the electrodes, the applied voltage threshold for thermoacoustic sound production was observed to decrease almost linearly for bursts up to ten cycles. At the time of these experiments, around 2014, we were unable to explain these sound production threshold values. A mass density continuity equation with a negative source term is used to explore the observed threshold values. The negative source term represents the decrease in fluid density with each half cycle of applied voltage due to the ohmic heating. This approach builds on an earlier heat balance model that successfully explains an observed delay in thermoacoustic sound production. Model results are compared with the experimental observations.
Experimental characterization of high intensity progressive ultrasound beams in air
Authors: Meng Yuqi , Vatankhah Ehsan , Liu Zihuan , Niu Xiaoyu , Williams Randall P. , Hall Neal A.
Published: November 2022

The majority of reported measurements on high intensity ultrasound beams in air are below 40 kHz and are performed on standing waves inside a guide. Here we present experimental characterization of high intensity progressive and divergent sound beams in air at 300 kHz. Measurements in this frequency range are challenging. Accurate characterization of high intensity sound beams requires a measurement bandwidth at least 10x the beam's primary frequency, as high intensity soundwaves steepen and form shocks, and therefore contain significant signal power at harmonic frequencies. A measurement bandwidth of at least 3 MHz is therefore required. Calibrated measurement microphones are generally not available in this frequency range. We have overcome this limitation by using a hydrophone with a calibrated response from 250 kHz—20 MHz. A narrowband piezoelectric transducer is used as the source in this study. The source is capable of generating tone burst waveforms centered at 300 kHz and with 160 dB SPL surface pressure. Cumulative wave steepening and shock formation are observed in on-axis measurements. The source's surface vibration profile is measured using a scanning LDV, and the vibration profile is imported into a numerical wide-angle KZK simulation for comparison against measured on-axis waveforms.
The effects of vowel, pitch, and dynamics on the emotional characteristics of the Soprano, Alto, Tenor, and Bass Voices
Authors: Chang Bing Yen , Law Man Hei , Chan Hiu Ting , Horner Andrew B.
Published: November 2022

Previous research on the soprano and tenor voices have shown that their emotional characteristics change with different vowel, pitch, and dynamics. This work continues the investigation with the alto and bass voices. Listening tests were conducted whereby listeners gave absolute judgements on the SATB voice tones over ten emotional categories with the data analyzed using logistic regression. High-arousal categories were stronger for loud tones, whereas low-arousal categories were stronger for soft tones. The categories Happy, Heroic, Romantic, and Shy had mostly upward trends across the pitch range, whereas Angry had an overall downward trend. Calm and Sad had an arch-shaped trend, while Scary had a U-shaped trend. Comic and Mysterious had different trends among the voices. The voices each exhibited different vowel trends, though vowel A was dominant for all the voice types in the categories Happy and Romantic. Dynamics had the strongest effect overall, followed closely by pitch, with both effects approximately twice as strong as the effect of vowel. Vowel U had the largest strength-of-expressiveness overall, with A second, O third, I fourth, and finally E last. These results give a quantified preliminary perspective on how vowel, pitch, and dynamics shape emotional expression in the SATB voices.
Analyzing field audio of parent-child book reading activities across various audio capture devices
Authors: Datla Sathvik S. , Dutta Satwik , Reyna Jacob , Buzhardt Jay , Irvin Dwight , Hansen John H.
Published: November 2022

Language ENvironment Analysis (LENA) is a light weight audio capture device commonly used to monitor language including frequency of parent-child interactions for research purposes. However, various factors including price and technical limitations often limit the use of LENA for low-income families. Using a smartphone can be a feasible alternative when LENA is not available to practitioners/families. Over the past three decades, significant advancements have resulted in smartphone platforms/microphones/technology, allowing for high quality recorded audio which are available in most households. In this study we compare audio quality and measure performance of several Automatic Speech recognition (ASR) engines on audio captured from iPhone and Android relative to LENA devices. Families who consented in this study recorded reading activities with their children at home using both personal smartphones and LENA. Some challenges we found include recording synchronization, unnecessary background noises, and uneven room acoustics. Audio quality comparison is measured using Speech-Signal-to-noise ratio (SSNR) metric. Both open-source and fine-tuned ASR models are explored, with results reported using overall Word Error Rate (WER), as well as separated by speaker–Child versus Adult. Results show that smartphone platforms can be used versus LENA for child-adult language assessment. [Work sponsored by NSF through Grant Nos. 1918032 and 1918012.]
Variations in sound transmission loss through vertical mass-decoupled partitions installed with a comprehensive sample of resilient channels
Authors: Shafer Benjamin M.
Published: November 2022

Resilient channels are commonly employed as a sound isolation treatment in building partition assemblies. Originally designed and patented as a crack-mitigation component in gypsum wallboard partition assemblies, the development and application of resilient channels as a mass-decoupling treatment for sound isolation in building partitions has achieved widespread acceptance in the building industry. Several recent laboratory sound transmission loss (STL) studies illustrate statistically significant variability in STL for steel-framed partitions. This experimental analysis attempts to more comprehensively characterize the variability in STL through mass-decoupled vertical partitions that employ steel resilient channels as a sound isolation treatment. Ten different models of resilient channels produced by five different manufacturers were tested with both damped and undamped panel configurations in a same-laboratory, same-series research program. Over 120 total tests were completed in this experimental study. The results of this study and recommendations for sound isolation design and specification are discussed.
Adventures in lab testing: Optimizing a new construction floor-ceiling acoustics lab
Authors: Way Evelyn
Published: November 2022

The Maxxon Acoustics Lab, a purpose-built, floor-ceiling test lab was completed at the end of 2021, but the verification process was just beginning. Results coming out of the lab were verified using slabs tested at another lab and wood frame assemblies compared to historical data collected on comparable assemblies. The iterative process of modifying mounting conditions will be presented, and data will be analyzed based on test condition modifications and lab facility differences.