26 Jan

Seminar: New Orleans Airlift

Join us for our second seminar of the spring semester for a glimpse at an amazing project that lies at the intersection of acoustics, art, culture, and architecture. Come hear members of New Orleans Airlift, a team of artists, musicians, and architects from New Orleans, discuss Dithyrambalina, a sonic playground, performance venue and laboratory for musical architecture in New Orleans.

Date: February 14th, 2014
Time: 11 am
Location: IC 107

As always, food will be provided!

Dithyrambalina

A host of international artists, musicians and inventors are creating Dithyrambalina – a landmark village of musical, playable houses. Invented instruments embedded into the walls, ceilings, and floors of Dithyrambalina’s architecture will support boundary-breaking musical performances and inspire wonder, exploration and invention in visitors of all ages. This New Orleans Airlift project is the evolving brainchild of artists Swoon, Delaney Martin, Taylor Lee Shepherd and Jay Pennington in collaboration with over 100 more artists and musicians to date. Last year they debuted THE MUSIC BOX, as a proof-of-concept for their vision. For more about Dithyrambalina, check out their website.

14 Jan

Speaker: Dr. Julien Meaud

Join us for our first ASA seminar of the spring semester! ME professor Dr. Julien Meaud will give a talk about his work on modeling the mammalian ear. See abstract below.

Date: Wednesday January 22nd
Time: 12 pm
Location: MRDC 4211

As always, food will be provided!

Computational Modeling of the Mammalian Ear

Due to the active feedback by outer hair cells in the cochlea, the mammalian ear is a complex sensory system with high sensitivity and sharp tuning in response to low level sounds and a broad dynamic range. Moreover, the mammalian ear can emit sound that can be non-invasively recorded in the ear canal in order to diagnose hearing pathologies. In this talk I will present the development of a computational model of the mammalian ear that couples a multiphysics model of the cochlea and a lumped parameter model of the middle ear. This model can be used as a virtual laboratory in order to test theories of hearing mechanics and to better diagnose hearing pathologies.

01 Dec

Winter Symposium 2013

Join us for our annual ASA Winter Symposium. This is an opportunity for students to present their most recent acoustics-related research results and to hear about the research your fellow students are involved with. If you are interested in presenting, please send a title and short abstract to Jason (jkulpe@gatech.edu). Presentations should be around 10 minutes each.

Winter Symposium 2013
Date: Thursday December 12th
Time: 4 pm
Location: MRDC 4211

As always, food will be provided!

15 Oct

Speaker: Dr. Tim Hsu

Join us for our next ASA seminar on musical acoustics! A presentation will be given by former ASA president Dr. Tim Hsu. See abstract below.

Date: Monday October 21st
Time: 12 pm
Location: MRDC 4211

Food is always provided – it will be delicious this time!

Historically Informed Performance and Musical Acoustics

It is a current trend amongst some musicians to attempt to play music in a historically informed fashioned. These performances, that often utilize period specific instruments, musicologically researched performance styles, historical pronunciations, as well as other period specific decisions, are labeled as historically informed performances. However, as musicians and musicologists explore performance practices, the field of historically informed acoustics attempts to study the acoustics of historical spaces and the modeling and simulation of historical instruments. A highly interdisciplinary field, historically informed acoustics is a cross-section between acoustics, music performance, and musicology. This talk explores these musical acoustical topics and gives examples of some extant and non-extant performances spaces and instruments. These examples will include the current state of acoustical measurements in some extant churches in Venice as well include some of the research challenges in this field.

20 Aug

Fall 2013 General Meeting

Want to learn more about ASA and our plans for the Fall semester? Please join us for our Fall 2013 general meeting. We will discuss the following topics:

* What is ASA?
* How can I get involved?
* Outreach activities, social activities, acoustic lecture series

Food will be provided!

Date: Tuesday September 10th
Time: 11 am
Location: Love 185

01 Apr

Speaker: Dr. Jennifer Michaels

Join us this Thursday for our final ASA spring 2013 lecture! The speaker will be ECE professor Dr. Jennifer Michaels. Below is a brief description of the lecture topic and her research background.

Guided Wave Structural Health Monitoring with Spatially Distributed Arrays

Ultrasonic waves have the potential to interrogate critical structures for damage, and many researchers are actively considering them for structural health monitoring (SHM) applications. Unlike nondestructive evaluation (NDE), where transducers interrogating a very small region are manually or automatically moved to obtain complete spatial coverage, in situ transducers for SHM are fixed in space. However, the constraints of spatially fixed transducers can severely limit the performance of such an SHM system, particularly in complex structures subjected to variable operational and environmental conditions. In this presentation, guided wave imaging methods are described for SHM using spatially distributed arrays; the context is current and past projects of the QUEST Laboratory at Georgia Tech. Results presented not only demonstrate recent progress but also point out the need for additional research and development efforts so that obstacles preventing widespread adoption of guided wave SHM systems can be overcome.

Date: Thursday, April 4th, 2013
Time: 11:00 am
Location: Love Bldg. Rm 109

Dr. Jennifer E. Michaels is a Professor in the School of Electrical and Computer Engineering at Georgia Tech and is serving as Interim Associate Chair of ECE Undergraduate Affairs. She received the Bachelor’s of Electrical Engineering degree from Georgia Tech in 1976, and began working in the field of ultrasonic nondestructive evaluation at the Hanford Engineering Development Laboratory in Richland, Washington. This work led to her graduate studies in Theoretical and Applied Mechanics at Cornell University, where she earned her M.S. and Ph.D. degrees in 1982 and 1984, respectively, and then spent a year as an IBM Postdoctoral Fellow. From 1985 until joining Georgia Tech in 2002, she worked in industry, first as co founder of a startup company, and later as Manager of Systems Development at Panametrics, Inc., a world leader in the development, fabrication and deployment of custom automated ultrasonic inspection systems. At Georgia Tech she is co-director of the QUEST (Quantitative Ultrasonic Evaluation, Sensing and Testing) Laboratory, where current projects relate to ultrasonic structural health
monitoring and nondestructive evaluation.

Professor Michaels is a member of the Acoustical Society of America and the American Society of Nondestructive Testing, and is a senior member of IEEE. She is currently serving as Associate Editor of Ultrasonics and The International Journal of Structural Health Monitoring. Her general research interests include signal processing, wave propagation, pattern recognition, detection and estimation, data fusion, sensing methods and measurement systems. Current and past sponsors of her work include AFRL, AFOSR, DARPA, HSARPA, NASA, NSF and industry.

05 Mar

Speaker: Dr. Karim Sabra

Join us next Tuesday for our 2nd ASA spring 2013 lecture! The speaker will be ME professor Dr. Karim Sabra. Below is a brief description of the lecture topic and his past experience in acoustics.

Update 3/11/2013: There has been a change in the lecture topic. Please see below for information about the new topic.

High-frequency SONAR imaging fundamentals

SONAR is an acronym for SOund Navigation And Ranging. The basic principle of sonar is to use sound to detect or locate objects, typically in the ocean. Sonar technology is similar to other technologies such as: RADAR (RAdio Detection And Ranging); ultrasound, which typically uses higher frequencies for medical applications; and seismic processing, which typically uses lower frequencies in sediments. The principle of Synthetic aperture sonar (SAS) is to combine successive pings coherently along a known track in order to increase the azimuth (along-track) resolution. SAS has the potential to produce high resolution images down to centimeter resolution up to hundreds of meters range. I will present the physical principles and signal processing underlaying SAS. Several examples will be introduced to show that SAS a suitable technique for imaging of the seafloor for applications such as search for small objects, imaging of wrecks, underwater archaeology and pipeline inspection

Date: Tuesday, March 12th, 2013
Time: 11:00 am
Location: Love Bldg. Rm 109

Karim Sabra is currently an Associate Professor of Mechanical Engineering at the Georgia Institute of Technology. Prof. Sabra joined the Georgia Institute of Technology in July 2007. Prior to this he was a Project Scientist (for 2 years) and Postdoctoral researcher (for 2 years) at the Marine Physical Laboratory of the Scripps Institute of Oceanography at the University of California at San Diego. Prof. Sabra graduated with his PhD in Mechanical Engineering in 2003 from the University of Michigan at Ann Arbor, completing his PhD studies in 3 years. Prof. Sabra teaches and performs research on acoustic and elastic wave propagation. Dr. Sabra’s awards include election as a Fellow of the Acoustical Society of America in 2007, the 2009 A.B. Wood medal from the Institute of Acoustics (UK) for his significant contributions to the field of underwater acoustics and the 2011 R.B. Lindsay award from the Acoustical Society of America for significant contribution to time-reversal and ambient noise correlations.

01 Mar

Dr. Julien Meaud Faculty Candidate Seminar

There will be an upcoming faculty candidate seminar given by Dr. Julien Meaud on the non-linear dynamics of the cochlea. See below for more information about this interesting topic!

Simulating the active nonlinear dynamics of the cochlea using a computational multi-physics model

The mammalian ear is able to sense faint sounds (down to 0 dB SPL), distinguish between close frequencies (0.1% apart) and operate over a broad range of sound intensities (6 orders of magnitude). This striking performance is due to the presence of an active feedback mechanism linked to outer hair cell activity in the sensory organ of the inner ear, the cochlea. Thanks to this feedback mechanism, called cochlear amplifier, the cochlea is a nonlinear system that exhibits high sensitivity and sharp tuning in response to low level sounds and a broad dynamic range. Failure of the cochlear amplifier due to diseases, ototoxic drugs, sound overexposure or aging causes deafness or hearing loss. Better understanding of how the cochlea processes sounds is needed to better protect hearing, diagnose hearing pathologies and treat hearing loss. Development of computational models of the cochlea allows testing theories of active cochlear mechanics and could have both scientific and clinical applications. In this talk I will present a nonlinear multi-physics model of the cochlea. This computational model, formulated in the frequency domain using an alternating frequency/time method, couples the mechanical, electrical and acoustical domains of the cochlea using finite element methods and includes detailed models for the biophysics of outer hair cells. I will demonstrate that this physically-motivated model is able to simulate the main aspects of the nonlinear response of the cochlea to single-tone and two-tone stimuli. Finally, I will show that the model can be used as a virtual laboratory that can test for example the effect of genetic mutations on cochlear tuning.

Date: Wednesday, March 27th, 2013
Time: 11:00 am
Location: MRDC Rm 4211

Julien Meaud is currently a Research Fellow in the Vibrations and Acoustics Laboratory in the Department of Mechanical Engineering at the University of Michigan, Ann Arbor, where he works on computational cochlear mechanics under the supervision of Prof. Karl Grosh. He studied engineering as an undergraduate at the Ecole Centrale de Lyon in France. He received a Master of Science in 2006 and a Ph. D. in Mechanical Engineering in 2010, both from the University of Michigan. His work on cochlear mechanics has been published in the major journals of acoustical and biophysical research. He was awarded a best student paper award at the 2009 Acoustical Society Meeting for a presentation of his computational model of the cochlea. Prior to his current postdoctoral appointment, he worked with Prof. Gregory Hulbert as a Research Fellow in the Computational Mechanics Laboratory at the University of Michigan and investigated the mechanics and design of composite materials with high stiffness and high damping in response to dynamic loads.

05 Feb

2013 ASA Elections & Pindrop Security

Our first meeting of 2013 will be our officer election meeting. Please come and be active in our organization!

Date: Friday, February 8th 2013
Time: 11:00 am
Location: Love Building Rm 109

Also stay tuned for our first lecture series of the new year with Pindrop Security. Pindrop Security (www.pindropsecurity.com) is a start-up company in ATDC, with offices in Tech Square. Pindrop was co-founded by then-GT student Dr. Vijay Balasubramaniyan and his advisor, Prof. Mustaque Ahamad, based upon the results of Balasubramaniyan’s doctoral thesis, which investigated the provenance of telephone calls via characteristics of their inbound audio streams.

Balasubramaniyan and Ahamad quickly recognized the enormous business potential of a product that could reliably identify the geographic source and technological origin of a phone call, and formed a company over two years ago. After obtaining sufficient resources, they began hiring employees in 2011. Spence Whitehead was the second engineer hired, a PhD student at Georgia Tech, researching methods of enhancing the quality of speech distorted by ambient noise.

Pindrop Security provides a comprehensive solution to detect and block fraudulent calls into financial institutions. Our breakthrough acoustic analysis technology analyzes live or recorded call audio to determine caller location and calling device type. The technology creates a unique acoustic “fingerprint” that identifies each caller and can link them to other malicious activity – even if done using different phone numbers. Pindrop Security is now helping top financial institutions fight back against phone fraud.

Date: Thursday, February 14th 2013
Time: 11:00 am
Location: Love Building Rm 109

04 Dec

Winter Symposium 2012/End of Semester Celebration

In two days we will be holding our second annual ASA symposium. This year we will hear interesting talks from the student body here at Georgia Tech. See the list below for this year’s speakers and presentation topics. Please make an effort to come and support your lab mates, students, or friends. Again we will also have a full spread of food as we wrap up another great semester. Feel free to bring friends to this event.

ASA Winter Symposium
Time: Thursday December 6th 4:30 -7p
Location: MRDC 4211

Presenter: Drew Loney
Title: Acoustic analysis of a horn-based ultrasonic ejector for viscous fluid atomization
Abstract: An analytical model of a horn-based ultrasonic atomizer is developed for investigating droplet generation from high viscosity fluids. The simulated device incorporates a piezoelectric transducer, a fluid reservoir, and a micromachined silicon array of acoustic liquid horn structures as ejection nozzles. When driven at resonant frequencies of the fluid cavity, a locally increased pressure gradient results at the horn aperture. Previous experimental work showed the capability of the atomizer to eject high viscosity fluids, overcoming a limitation traditionally associated with piezoelectric inkjets. This work focuses on the acoustics of the device, developing a quasi-one-dimensional, analytical model of the device which is validated with finite element analysis simulations. Emphasis is placed on accounting for viscous effects such as wave attenuation and viscous boundary layer losses. The effect of viscous attenuation on the pressure gradient magnitude at horn aperture – the parameter which defines the threshold for the fluid ejectability – is also investigated.

Presenter: Brendan Nichols
Title: Locating Sources with Vector-Sensor Beamforming
Abstract: Locating objects in an ocean environment is a key component in naval defense as well as marine mammal observation. Localization can be performed using beamforming, a technique which combines data from multiple sensors to estimate the position of a source. This technique can also be applied to vector sensors, which are capable of measuring both acoustic pressure and particle velocity. To determine the effects of sensor position and uncertainty on the localization accuracy, simulation code was implemented to test the beamforming method and its accuracy under various conditions.

Presenter: Shima Shahab
Title: Outgoing Waves from a Fully and Partially Submerged Cylindrical Pile
Abstract: Pile driving can produce underwater sound pressures exceeding 200 dB at ranges greater than 100 meters. Methods are needed to predict sound levels and develop appropriate mitigation techniques for potentially harmful sound exposures. A finite-difference time-domain (FDTD) formulation is presented to analyze sound produced from a large steel pile. Following an impact hammer strike, a stress wave travels down the pile wall and produces expansions and contractions in the radial direction, which couple with the surrounding fluids to create propagating sound waves. Results of correlations between radiated sound fields predicted by the FDTD model and acoustic field data are presented.

Presenter: Shane Lani
Title: Coherent processing of shipping noise for ocean monitoring
Abstract: Extracting coherent wavefronts between passive receivers using cross-correlations of ambient noise may provide a means for ocean monitoring without conventional active sources. Hence applying this technique to continuous ambient noise recordings provided by existing or future ocean observing systems may contribute to the development of long-term ocean monitoring applications such as passive acoustic thermometry. To this end, we investigated the emergence rate of coherent wavefronts over 6 days using low-frequency ambient noise (f < 1.5 kHz) recorded on two vertical line arrays-separated by 500m- deployed off San-Diego CA in ~200m deep water. The recorded ambient noise was dominated by nonstationary distributed shipping activity with the frequent occurrence of loud isolated ships. Noise data were first processed to mitigate the influence of these loud shipping events in order to primarily emphasize the more homogenous and continuous background ambient noise in the frequency band. Furthermore, the coherent noise field propagating between the VLAs was beamformed using spatio-temporal filters to enhance the emergence rate of specific coherent wavefronts. This presentation will discuss various strategies for the selection of these spatio-temporal filters (either data-derived or model-based) in order to improve the continuous tracking of these coherent wavefronts over 6 days.

Presenter: Katherine Woolfe
Title: Results of a scaled physical model to simulate impact pile driving
Abstract: To have a better understanding of the parameters involved in the structural acoustics modeling of pile driving, a scaled physical model has been created. By measuring the radial wall motion of the model and comparing this with the pressure measured by two separate hydrophone arrays, the effects of fluid loading upon wall motion can be observed in both the time and frequency domains. The intensity data obtained from this model can be used to analyze the transient energy exchange between the structure and the water, showing that energy radiated into the fluid re-enters the structure when the wall motion attenuates.

Presenter: Toby Xu
Title: Investigation of Dual Mode Side and Forward Looking IVUS Using a Dual Ring CMUT-on-CMOS Array
Abstract: Forward looking (FL) capability is desired in IVUS catheters to enable real time volumetric visualization of especially nearly or fully blocked arteries to guide interventions. The addition of side looking (SL) capability in the same catheter would be valuable to locate the device with respect to vessel walls and provide a conventional image to the clinicians. A single chip CMUT-on-CMOS array may provide both capabilities while enabling an extremely flexible catheter tip implementation. In this study, the combined side and forward viewing ability of the CMUT-on-CMOS IVUS array is investigated and initial experimental results are presented. To demonstrate SL imaging, we used a 20-MHz single chip dual-ring CMUT-on-CMOS array with 56 transmit and 48 receive elements fabricated on a 1.5-mm diameter 0.3-mm thick silicon donut. We placed four vertical wire targets close to the array plane and a front wire located above the same array. The frequency spectrums of the side and front targets have a center frequency of 12 MHz and 20 MHz, respectively. We also performed finite element method (FEM) simulations to obtain the frequency spectrums of the transient pressure signals at 0° and 90° which showed the same center frequencies. These results show promise for the viability of FLIVUS CMUT-on-CMOS device with dual mode side-forward looking imaging.