Generating Nonreflective Mechanical Traveling Waves in
Finite Media with Applications: Modeling and Experiments
Friday, November 10, 2023, 4:00 p.m. Central Time
Professor Pablo A. Tarazaga
J. Mike Walker ’66 Department of Mechanical Engineering
Texas A&M University
https://engineering.tamu.edu/mechanical/profiles/tarazaga-pablo.html
In this talk we will discuss nonreflecting mechanical waves in finite media. It is well known that as mechanical waves reach the boundaries of a finite medium, the impedance mismatch causes wave reflections that in steady state conditions (and low damping) result in standing waves. The work herein will discuss ways to use inputs (two-point excitation method) and discontinuities (springs and dashpots) to create nonreflecting traveling waves throughout or in sections of the host medium. The study of such work has several areas of application such as in particulate transport (continuous conveyor belts), mimicry of marine locomotion, noncontact fluid mixing, and in the behavior observed in the basilar membrane of mammalian cochlea. The presentation will discuss some of the basic models developed, the experimental validations and challenges, and some examples of how they can be implemented.
Tailoring Material Properties by Laser Excitation of
Optical and Acoustic Phonon Modes
Friday, October 27, 2023, 4:00 p.m. Central Time
Professor Edoardo Baldini
Department of Physics
The University of Texas at Austin
https://baldinilab.org//
The ability to precisely tune quantum material properties at ultrafast (i.e., sub-picosecond) time scales is key to opening new routes toward high-speed optoelectronic, spintronic, and quantum devices. Ultrashort laser pulses have the potential to engineer various interactions at the meso- and nano-scale, steer phase transitions along preferential pathways, and coherently control structure-function relationships. This tailored quantum material design by light relies on different manifestations of the light-matter interaction, requiring an exquisite control over the properties of the light field itself. In this talk, I will discuss how the laser excitation of specific vibrational modes can yield new forms of nonequilibrium functional control in quantum materials, leading to the modification of optical, magnetic, ferroelectric, and topological properties. In particular, I will focus on the resonant driving of optical phonon modes to induce symmetry-breaking phase transitions and on the coherent excitation of acoustic phonon modes to manipulate high-energy quasiparticles. Finally, I will describe the opportunities offered by novel schemes based on nonlinear acoustics to explore a wider portion of the potential energy landscape and stabilize exotic quantum phases of matter that have no counterpart in thermodynamic equilibrium.
VIacoustics – A Year in Review
Friday, October 20, 2023, 4:00 p.m. Central Time
Jeff G. Schmitt, P.E.
VIacoustics
Austin, Texas
https://viacoustics.com/
Jeff Schmitt received his master’s degree in acoustics at UT in 1983, studying under Dr. David Blackstock and Dr. Elmer Hixson. Since his graduation he has been an “acoustics entrepreneur,” operating an acoustical enclosures manufacturing company, an acoustical consulting practice, and now a small Austin-based acoustics business. His current company, VIacoustics, is a small business that provides systems and software for a wide variety of acoustical measurement and signal processing applications. This presentation will provide an overview of the variety of projects that VIacoustics has worked on over this past year. Project summaries will include: System for testing the performance of hearing protection systems for both industrial and military noise applications; System for testing the compliance of medical device alarms with standardized requirements; System for determination of the sound power levels emitted by HVAC equipment; System and signal processing for measurement of decay rates in a reverberation chamber using a swept sine and backward integrated impulse response; Signal processing algorithms for evaluation of the psychoacoustic sound quality for products. A short summary of each of these projects will be presented, followed by an open session for attendees to ask additional questions about each of these projects.
Acoustics-Based Technology: Pursuing a Startup
Friday, October 13, 2023, 4:00 p.m. Central Time
Dr. George Hutchinson
Chief Executive Officer
Invictus Medical, Inc.
San Antonio, Texas
http://www.invictusmed.com/
Invictus Medical has developed an active noise control product for use in the neonatal intensive care unit through a combination of strategic technology in-licensing and internal development. Utilizing a combination of an industry-experienced team, key university relationships, and strategic application of contractors, an initial license agreement has led to an FDA-cleared medical device. This process is discussed focusing on these primary pillars: technology development, intellectual property protection, funding, governance, marketing, team selection, regulatory compliance, and quality systems. Lessons learned and applicability to other industries are discussed.
Scaling of Acoustic Resonators into the Millimeter Wave Regime Using Piezoelectric Thin Films
Friday, October 6, 2023, 4:00 p.m. Central Time
Professor Ruochen Lu
Chandra Department of Electrical and Computer Engineering
The University of Texas at Austin
https://www.ece.utexas.edu/people/faculty/ruochen-lu
Piezoelectric acoustic resonators are the dominant radio-frequency front-end filtering solution in mobile devices, thanks to their miniature footprint and better frequency selectivity. In piezoelectric resonators, electromagnetic (EM) signals are converted into, and processed as, acoustic signals, which results in a 10 times higher quality factor (Q) and 105 times shorter wavelengths than their EM counterparts. Recent studies have aimed to reproduce the success of acoustic resonators at 6 GHz in the millimeter wave (mmWave) regime, i.e., at frequencies greater than 30 GHz. However, such frequency scaling calls for innovation from both material-level development and device-level design. We will first discuss the operating principles of miniature piezoelectric resonators and their applications in signal processing. Next, we will examine the fundamental limits for frequency scaling, then showcase periodically poled piezoelectric film (P3F) transferred to thin-film lithium niobate (LiNbO3) as a promising platform, achieving a 50 GHz acoustic resonator with a high electromechanical coupling (k2) of 7.55% and 3 dB quality factor of 222. This collectively enables a record-breaking figure of merit given by k2Q = 16.8, which is an order of magnitude higher than the state-of-the-art acoustic resonators at the same frequency. Finally, we will report on the recent demonstration of mmWave acoustic filters, and discuss the future challenges and opportunities in mmWave acoustics.
Acoustic Radiation Force: History, Theory, and Applications
Friday, September 29, 2023, 4:00 p.m. Central Time
Dr. Thomas S. Jerome
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/
Radiation force has a long history of study, throughout which it has captured the attention of many scientists of great influence in diverse fields of study. Radiation force is a nonlinear phenomenon whereby a wave, either acoustic or electromagnetic, exerts a force due to conservation of the time-averaged momentum carried by the wave when interacting with an object or material. This talk provides an overview of the study of acoustic radiation force, its historical development, theoretical basis, and modern applications. Beginning with its roots as one of the many acoustic phenomena first theorized in electromagnetics, the historical context for the study of radiation force is provided, including major developments in theory and experimental observations. The basic theoretical principles of radiation force are discussed, with special attention devoted to acoustic radiation force due to the scattering of sound from an object, and an overview of theory for radiation force and torque exerted on irregularly shaped objects. Historical and contemporary applications of acoustic radiation force are reviewed, including examples of acoustic levitation, particle manipulation, transducer calibration, and medical imaging.
Can You Hear Me Now?
What Clear Speech Can Teach Us about Perceptual and Cognitive Processing
Friday, September 22, 2023, 4:00 p.m. Central Time
Professor Rajka Smiljanic
Department of Linguistics
The University of Texas at Austin
https://liberalarts.utexas.edu/linguistics/faculty/rs6634
In daily communication, we frequently encounter situations where speech intelligibility varies significantly. These may involve conversations in noisy classrooms or medical clinics, with speakers who have non-native accents, or are wearing protective face masks, and listeners who may be elderly individuals with hearing impairments or professionals from diverse linguistic backgrounds. In response to such challenges, speakers often employ clear speech: a deliberate adjustment involving slowed speech, expanded pitch variations, and precise phoneme articulation, with a goal of enhancing intelligibility. In this talk, I will share a program of research aimed at understanding the perceptual and cognitive processes that underlie the successful comprehension of variably intelligible speech. Our findings provide evidence that clear speech not only enhances signal-dependent sensory processing but also deeper linguistic processing abstracted from the input speech. Additionally, the results suggest that listeners direct their selective attention toward acoustically more salient speech, thereby facilitating speech processing. Understanding how variations in speech clarity impact comprehension in everyday communication represents a theoretically interesting problem with direct applications in fields such as education, healthcare, and speech recognition.
Wavefront Control via Reconfigurable Elastic Metasurfaces
Friday, September 15, 2023, 4:00 p.m. Central Time
Professor Serife Tol
Department of Mechanical Engineering
University of Michigan
https://me.engin.umich.edu/people/faculty/serife-tol/
Wave propagation can be tailored and manipulated with periodically architected materials (a.k.a. metamaterials, phononic crystals, and metasurfaces). Among others, metasurfaces have recently gained increasing research interest due to their ability to control elastic/acoustic wavefronts with a compact footprint, which is especially desired for low-frequency applications. This talk highlights reconfigurable elastic metasurfaces, which can be tailored to the desired phase modulation and wavefront manipulation by tuning either the structural elements of the passive metasurface or the external electrical stimuli on the electromechanical metasurface. To this end, we present three approaches to tunable elastic wave control via (i) a reflective metasurface, (ii) an origami-inspired metasurface, and (iii) an electromechanical metasurface. The reflecting metasurface is formed by locally resonant elements based on threaded rods and nuts, and the phase properties of the metasurface are controlled by changing the amount of nuts’ screw distances. In addition to controlling antisymmetric (A0) mode Lamb wave propagation, mode conversion is also exploited to manipulate symmetric (S0) mode Lamb waves. In the second metasurface, an array of zigzag-based folded sheets with parallel corrugations is used to control the wavefront of the refracted A0 Lamb mode wave. Our results show that the origami-inspired metasurface can reconfigure the wavefront by changing its folding angle. Finally, in the last case, we present a piezoelectric-based metasurface that is connected to individual inductive electrical loads and tailor the phase modulation according to the desired wavefront, including wave focusing and deflection. We show that through single and multi-resonant electrical shunts, propagating A0 mode Lamb waves can be controlled in a tunable and broadband fashion, achieving the desired dynamic function.
Northern Ocean Rapid Surface Evolution (NORSE) Experiment:
Trip Report and Initial Observations of Acoustic Propagation
Friday, September 8, 2023, 4:00 p.m. Central Time
Dr. Megan S. Ballard
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/
The Northern Ocean Rapid Surface Evolution (NORSE) focuses on characterizing the key physical processes that govern the predictability of upper-ocean rapid evolution events. The principal experimental site is Jan Mayen Channel, which connects the Greenland and Norwegian Seas. This talk describes the suite of measurements collected during the fall 2022 process cruise and provides a glimpse of life onboard the research vessel. Initial results showing a unique set of observations of three-dimensional (3D) acoustic propagation collected during the process cruise will also be presented. These 3D measurements originated from signals produced by a moored source that were recorded by three surface drifters equipped with hydrophone arrays. Over a three-day period, the drifters moved north across Jan Mayen Channel toward the moored source. In recordings with positive SNR, an in-plane arrival is observed. In a subset of these recordings, a second arrival is observed having travel time consistent with a propagation path from the moored source, reflecting off the ridge on the south side of the channel, and arriving at the drifters. A third arrival is also observed having travel time consistent with reflection from the face of the bathymetric rise on the east end of the channel which forms Jan Mayen Island. This talk will present the measurements and explain the data through forward modeling.
Audio Forensics: Recorded Audio Analysis with Case Examples
Friday, September 1, 2023, 4:00 p.m. Central Time
Steven D. Beck
Beck Audio Forensics
Austin, Texas
https://beckaudioforensics.com
Audio forensics is the field of forensic science relating to the acquisition, analysis, and evaluation of sound recordings that may be used as evidence in a court of law. In addition to properly handling evidence, an Audio Forensics Expert must be able to answer specific questions related to the acoustics and audio sources involved in a crime scene and to justify those answers with a reasonable degree of scientific certainty. Some of the basic steps in an investigation involving audio analysis will be described. A short history of some of the main application areas (authentication, voice, and gunshot analysis) will be presented, along with a discussion of applicable acoustics and signal processing techniques. Finally, a number of “famous” audio forensics cases from the FBI and the speaker’s recent work on unsynchronized receivers and ballistic flow sounds will be presented.
Acoustics and Vibrations in Spatiotemporally-Modulated Media
Friday, April 14, 2023, 4:00 p.m. Central Time
Dr. Benjamin Goldsberry
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/
Over the past decade, there has been significant interest in studying acoustic, elastic, and electromagnetic wave phenomena in materials with space- and time-varying properties. Many works have shown that modulating a medium’s properties both in space and time leads to novel wave behavior that otherwise does not exist in normal passive materials, such as nonreciprocity. In this talk I will introduce the wave physics present in spatiotemporally-modulated media and detail our recent works, including nonreciprocal vibrations, scattering from spatiotemporally-modulated plates, and a nonreciprocal elastic wave circulator.
Development of a Laser Doppler Vibrometer-Based Non-Contact Damage Detection System for Cracks in Rail Head
Friday, April 7, 2023, 4:00 p.m. Central Time
Korkut Kaynardag
The Department of Civil, Architectural, and Environmental Engineering
The University of Texas at Austin
https://www.caee.utexas.edu/
Transverse defects (TDs), which are cracks located transversely in rail head, are one of the main causes of train derailments. Therefore, the railway transportation community is interested in the detection of such defects at speeds that do not obstruct the routine railroad operation. Accordingly, this research presents a novel non-contact damage detection system that consists of two laser Doppler vibrometers (LDVs) attached vertically in front of a rail car to measure guided waves in rail head, which are induced by rail-wheel interactions. This system uses the LDV measurements to detect a change in the relative amplitudes of the recorded waves caused by a defect. Therefore, the damage detection framework associated with the system operates as follows: 1) in the pre-processing stage, time-varying mean and impulsive noise in the recorded LDV signals are filtered and then the changes in the signals are quantified and monitored using moving standard deviation, 2) in the post-processing stage, two damage features, which are based on the relative change in the moving standard deviations and transfer functions between two measurement points are combined using multivariate statistical analysis to create a damage index that shows the location of rail segments which are affected by a defect. In this study, at first, the tasks performed to develop the system, which were extensive literature on rail vibrations, rigorous laboratory and in-situ testing, developing analytical formulations, and simulations, are explained. Then, the results of the system’s field tests, where rail segments consisting of a defect were identified, are presented elaborately.
I’ve Heard the Most Shocking Things About Aeroacoustic Resonance
Friday, March 31, 2023, 4:00 p.m. Central Time
Prof. Daniel Edgington-Mitchell
Monash University
Melbourne, Victoria, Australia
https://www.monash.edu/
Explosives have played an extensive role in underwater acoustics research and tactical military operations for many decades as a means of creating high amplitude, broadband underwater sound. Early deployments of explosive charges were made by oceanographers and scientists deploying sticks of dynamite with a strategic length of fuse, often lit by a cigar. A more modern device known as the Signal, Underwater Sound (SUS) charge has replaced this early method and been utilized by the military for many decades, primarily in oceanographic research to support anti-submarine warfare (ASW). Although SUS charges have proved successful on many fronts, accidents have been reported and led to calls for alternative underwater sound sources. This talk will review the history and physics of underwater explosive charges and present a general overview of alternative underwater sound sources. A variety of alternative underwater sound sources will be discussed, but focus will be on those primarily developed at Applied Research Laboratories: UT Austin over many decades such as the plasma sound source, the combustive sound source (CSS), and the rupture induced underwater sound source (RIUSS).
Underwater Explosives and Alternative Underwater Sound Sources
Friday, March 24, 2023, 4:00 p.m. Central Time
Andrew R. McNeese
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/
Explosives have played an extensive role in underwater acoustics research and tactical military operations for many decades as a means of creating high amplitude, broadband underwater sound. Early deployments of explosive charges were made by oceanographers and scientists deploying sticks of dynamite with a strategic length of fuse, often lit by a cigar. A more modern device known as the Signal, Underwater Sound (SUS) charge has replaced this early method and been utilized by the military for many decades, primarily in oceanographic research to support anti-submarine warfare (ASW). Although SUS charges have proved successful on many fronts, accidents have been reported and led to calls for alternative underwater sound sources. This talk will review the history and physics of underwater explosive charges and present a general overview of alternative underwater sound sources. A variety of alternative underwater sound sources will be discussed, but focus will be on those primarily developed at Applied Research Laboratories: UT Austin over many decades such as the plasma sound source, the combustive sound source (CSS), and the rupture induced underwater sound source (RIUSS).
Form and Function in the Developing Túngara Frog Larynx
Friday, March 10, 2023, 4:00 p.m. Central Time
Hans T. Bilger
Department of Integrative Biology
The University of Texas at Austin
https://integrativebio.utexas.edu/
Male túngara frogs (Physalaemus pustulosus) are faced with a conundrum: Their advertisement calls are attractive to both female frogs and frog-eating bats. Males do not begin producing advertisement calls until they are sexually mature. Is this because their vocal apparatus cannot phonate at earlier stages, or because subadult calls would be both conspicuous and sonically unattractive? We investigate this question using morphometric analysis and a lumped-element analysis technique known as bond graph modeling. Previously published túngara frog call production models are being informed by new diceCT measurements on a developmental series of male and female túngara frog larynges. If subadult male models produce key acoustical behaviors observed in the “whine” and “chuck” components of adult male advertisement calls, it will suggest that sexually immature túngaras could call—if they “wanted” to. This will be a work-in-progress talk.
The Role of Acoustics in Songbird Communication and Management During a Period of Rapid Environmental Change
Friday, March 3, 2023, 4:00 p.m. Central Time
Dr. Darren S. Proppe
Wild Basin Creative Research Center
St. Edward’s University
https://www.stedwards.edu/wild-basin
Humans work hard to create ideal spaces for acoustic communication. However, many animals that rely on acoustic communication must produce and intercept acoustic signals within a messy environment of obstacles, competing sounds, and masking anthropogenic noise. Over time, many species have developed acoustic signals that transmit best in their preferred habitats. But urbanization and the ever-expanding human footprint are quickly modifying our natural soundscapes. For songbirds, many of whom learn their songs during development, the question is: Can they modify or adapt their vocalizations quickly enough to overcome the novel challenges that human noise presents for their established communication systems? We will explore the mechanisms that songbirds use to maximize sound transmission in changing environments, and review the impacts on species who appear unable to mitigate environmental change. Further we will investigate whether acoustics can be used by biologists and land managers as a tool to promote adaptive behaviors in songbirds. A deeper understanding of animal communication can beneficially inform the goals and activities of biologists, engineers, and city planners alike since a quieter natural world will benefit both humans and wildlife communities.
Waveform Coalescence in Supersonic Jet Noise
Friday, February 24, 2023, 4:00 p.m. Central Time
William A. Willis
Applied Research Laboratories
The University of Texas at Austin
https://wwwext.arlut.utexas.edu/gdl/
Jet noise has been a problem of interest since the adoption of the turbojet engine, with supersonic jets in particular exhibiting high noise levels. Turbulence mixing noise, as a component of supersonic jet noise, is dominated by the radiation of Mach waves at sufficient amplitudes to manifest cumulative nonlinear waveform distortion. Following the observation that lab-scale supersonic jets exhibit higher levels of distortion than predicted by theory, it was proposed that the coalescence of Mach waves propagating and intersecting at small angles could contribute to this phenomenon. The formation of steep wavefronts related to “crackle,” a particularly annoying aspect of jet noise, could also be affected by coalescence. This talk will present work performed at the Gas Dynamics Laboratory at ARL:UT to understand the coalescence process and its impact on nonlinear distortion. Coalescing waves have been modeled using numerical simulations and spark source experiments, with the latter captured at high frame rates using schlieren imaging. Methods to identify coalescing waves in schlieren images and large-eddy simulation of a lab-scale jet, including the application of neural networks for image classification, will also be presented.
Acoustic Design of Multi-Use and Flexible Spaces for Higher Education
Friday, February 10, 2023, 4:00 p.m. Central Time
Kaitlyn Hunt
Kirkegaard Architectural Acoustics
Houston, Texas
https://www.kirkegaard.com/
The first questions an acoustician asks a user when designing or renovating a space are, “What are you hoping to do in this space? What will be its use?” As acoustic consultants, our role is to then help the architectural design team define appropriate dimensions and set criteria for the three disciplines of architectural acoustics: sound isolation, noise control, and room acoustics. More and more owners and users respond that the room will be multi-use, interdisciplinary, and needs to be a flexible space with immersive audio and video that encourages innovation and collaboration. This is an exciting task, but what does all that mean? What are the acoustical design parameters if the goal is to support anything and everything? If we don’t specifically define the room’s use, how can we specifically design for the room’s use and avoid a “master-of-none” space? How do we give the client an inspiring and fully functional room, without exceeding the budget? Examples of how Kirkegaard approaches acoustical design and how we are continuing to develop and refine our process to this increasingly common design challenge will be shared.
Visual Learning of Sounds in Spaces
Friday, February 3, 2023, 4:00 p.m. Central Time
Changan Chen
Department of Computer Science
The University of Texas at Austin
https://www.cs.utexas.edu/
Humans use multiple modalities to perceive the world, including vision, sound, touch, and smell. Among them, vision and sound are two of the most important modalities, which offer complementary information about each other. Recent audio-visual learning research has made a lot of progress on object-level audio-visual correspondence, e.g., the image of a dog corresponds to the barking sound and the lip movement tells us what the person is speaking. Beyond instance-level correspondence, when sound waves are produced by object vibrations, they propagate and attenuate in the air, reflect off, get absorbed or transmit through surfaces, and then reach our ears. Our ear canals then shape the sound in a unique way that allows us to localize the sound without looking at the objects. All of these acoustic and spatial correspondences are captured by vision, e.g., we could visually localize a sound emitter and identify if a space has a lot of reverberation. This is of vital importance for applications such as egocentric video understanding, robotic perception, AR/VR, etc. In this talk, I’ll describe my recent efforts on developing acoustics simulation platforms, building embodied agents that can see and hear as well as modeling acoustics from vision.
2022 Wood Medal Lecture: Applications of Acoustical Oceanography
Friday, January 27, 2023, 4:00 p.m. Central Time
Dr. Megan S. Ballard
Applied Research Laboratories
The University of Texas at Austin
https://www.arlut.utexas.edu/
Acoustical methods are powerful remote sensing tools that can be applied to efficiently monitor underwater environments, alleviating the problem of space and time aliasing associated with traditional spot measurements. In this talk, both geoacoustic inference methods as well as direct measurements of acoustic properties of the water column and seabed are applied to understand geological processes and biological systems. Field experiments on the rapidly transitioning Pacific Arctic Region and vulnerable subtropical seagrass meadows of the Gulf of Mexico are described. Each of these works represents a collaborative effort on the use of sound to make a contribution to diverse fields including physical oceanography, biology, and ecology. Complementary laboratory measurements are used to benchmark results, extend the frequency range of field measurements, calibrate sensors, and devise new measurement techniques. Computational models are applied to provide insight into the effects of environmental inhomogeneities on the propagation of measured signals. Key results on the use of sound to assess critical habitats and environmentally sensitive regions will be highlighted.