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2004 ACOUSTICS AREA SEMINARS
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SPRING SEMINARS |
FALL SEMINARS
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Acoustics Area Seminars are held Fridays at 4:00 in
Room 4.120 of the
Engineering Teaching Center II (ETC) Building, unless otherwise indicated. Parking is available nearby in the
San Jacinto Garage (PG1) and the
Speedway Garage (PG6).
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2004 SPRING SEMINAR SCHEDULE
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January 30, 2004
Professor Dennis McFadden,
Department of Psychology,
The University of Texas at Austin
Using Otoacoustic Emissions as a Window into Hormonal Events during Prenatal Development
The normal cochlea contains a series of elements known as the cochlear amplifiers. As a harmless by-product, these
amplifiers produce sounds called Otoacoustic Emissions (OAEs). OAEs exhibit sex differences that are present in
newborns as well as in adults. OAEs also exhibit differences in certain special populations of humans such as
opposite-sex twins, homosexuals, and children with attention-deficit/hyperactivity disorder (ADHD). Taken together,
the data suggest that OAEs can serve as a marker for the degree of androgen exposure a fetus receives during
prenatal development. Those data and their implications will be reviewed, and then OAE data from two species of
primates will be presented---rhesus monkeys and spotted hyenas. Spotted hyenas are an especially interesting species
in this context because the females are highly masculinized in body, brain, and behavior beginning at birth, suggesting
that their OAEs should be quite weak. Also, for both species, we obtained data from animals that were treated with
androgenic or anti-androgenic agents during prenatal development---an excellent experimental test of our suggestion
that high levels of androgens during prenatal development masculinize OAEs. Come to the talk and you will see if our
predictions about those animals were confirmed.
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February 6, 2004
Professor David T. Blackstock,
Department of Mechanical Engineering,
The University of Texas at Austin
History of Physical and Engineering Acoustics at Texas
Acoustics appeared as an academic field of interest at the University of Texas as early as the 1930s. Acoustical interests
were pursued by C. Paul Boner in the Physics Department and Lloyd A. Jeffress in the Psychology Department. They
were good friends. When World War II came, Boner and most of the other Physics faculty were called off to war work,
Boner as Associate Director of the Harvard Underwater Sound Laboratory (HUSL). Meanwhile, back at the campus,
someone had to teach freshman physics, and Jeffress did it. On returning to the University in 1945, Boner organized
the Defense Research Laboratory (DRL), which was housed in buildings where the present Law School now stands. A
radar and aeronautics laboratory at first, DRL became involved in underwater acoustics in the early 1950s, and by the
late 1950s that was its dominant work. During this period acoustics on the campus (except for hearing) was still limited
to the Physics Department. However, that interest waned and acoustics gradually began to make its way into
Engineering, beginning about 1960 with Elmer L. Hixson in the Electrical Engineering Department. In the middle 1960s
Mechanical Engineering began to be involved. DRL, which played a role in prompting ME to become interested,
changed its name to Applied Research Laboratories and moved to its current site at Balcones Research Center (now the
Pickle Research Campus). Today acoustics at the University is a flourishing interdisciplinary field involving students,
faculty, and research staff in many academic departments---ME, ECE, ASE&EM, Physics, Psychology, Linguistics,
Communication Sciences and Disorders, and Music---and ARL.
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February 13, 2004
Dr. David P. Knobles,
Applied Research Laboratories,
The University of Texas at Austin
Geoacoustic Inverse Problems for Sound Transmission in Shallow Seas
Sound transmission in shallow seas is significantly influenced by the geophysical structure of the seabed, both at the
surface and beneath the seafloor. The reasons include the proximity of the seafloor to the water-air interface of the
waveguide, and the commonly downward refractive character of the speed of sound as a function of depth within
the water column. While modern numerical methods can accurately solve the wave equation boundary value problem,
the details of the geophysical properties of the seabed are often unknown, and thus lead to inaccurate predictions.
Analysis and the ability to successfully predict the properties of sound propagation in such waveguides often require
the use of inversion methods to estimate the properties of the seabed from acoustic measurements made in the water
column. The inference of the seabed structure employs a simulated annealing approach to estimate seabed parameters
such as sound speeds, densities, and attenuations, and their uncertainties. Simulated annealing uses the analogy of
the thermodynamics of the formation of crystalline structures from heating certain types of material followed by a
long cooling period. Discussed are several examples of such analyses from experiments in the Gulf of Mexico and the
East China Sea. A variety of data are considered and include multi-frequency tonals with large source-receiver offsets,
time series data generated by impulsive sources and recorded on multiphone arrays, and received noise generated by
moving surface ships.
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February 27, 2004
Tom Jedrzejewicz,
Medical Ultrasound Consultant, Formerly with
Siemens Medical Solutions
Novel Strategies for Beam Formation: Line-by-Line Acquisition Zone Acquisition
The traditional line-by-line strategy to acquire ultrasound echo is described and compared to zone-based technique
for real-time B-mode imaging. The zone technique utilizes a broad transmit beam from which many receive beams
are formed, such that a full field of view image can be formed using only 5-15 transducer excitations. On receive,
the RF data is pre-processed and accumulated in a channel domain baseband I/Q memory, and then transferred to
a DSP-based imaging system, which performs dynamic receive focusing, detection, log compression, spatial filtering,
and scan conversion. This technique and architecture extracts more information from each transmit firing,
transforming the image formation rate problem from one of acoustic propagation time limitations, to processing
speed limitations and thus, leverages Moore Law. The basic technique and architecture will be discussed, as well
as providing several example images from different applications.
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2004 FALL SEMINAR SCHEDULE
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September 10, 2004
Professor Preston S. Wilson,
Department of Mechanical Engineering,
The University of Texas at Austin
The Interesting Effects of Added Complexity: The Acoustics of Elastic Waveguides and Liquid-Filled Impedance Tubes
The impedance tube has been used to study the acoustic properties of materials in air for years and is a mature
technology. The acoustic absorption of ceiling tiles and automobile mufflers are typical examples, and a number
of commercial impedance tubes are available. The need to investigate the acoustic properties of materials and
structures in a liquid environment is less prevalent, but can be very important in certain areas, such as
underwater acoustics and the design of dynamic hydraulic circuits. A practical liquid-filled impedance tube
(LFIT) is difficult to achieve and no commercial devices are available. The reason: In the air-filled case, the
walls appear rigid to an airborne acoustic wave. In the liquid-filled case, one must account for the motion of
the tube wall. This was achieved by modeling the LFIT as an elastic waveguide, which has a number of interesting
properties. These will be discussed along with the design of a high-precision LFIT, which primarily suppresses
these properties. Resulting LFIT measurements of the acoustic properties of a bubbly liquid and a water-saturated
marine sediment will be presented and compared to existing theory. It turns out, the complexity of these
materials also results in interesting acoustic behavior.
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September 24, 2004
Jack Shooter,
Applied Research Laboratories,
The University of Texas at Austin
Church Opal - 1975, Recovery and Analysis of Archival Data
In October 2002 the Office of Naval Research (ONR) sponsored a Convocation that reviewed the ocean acoustic
studies done from 1967 to 1992 under the U.S. Navy's Long Range Acoustic Propagation Project (LRAPP).
Beginning in 1972 LRAPP fielded self-contained assemblies of vertically distributed hydrophones as part of
environmental acoustic exercises in a variety of oceanic regions. Analog signals were recorded in a submerged
buoy on multi-channel magnetic tape. Presentation of results from a 1975 measurements exercise in the Northeast
Pacific stimulated interest in recovering and digitizing the 10-day dataset from 13 hydrophones. ONR sponsored
a pilot project to demonstrate the feasibility of recovering the data and setting up digital files while preserving
absolute accuracy. The original magnetic tape was sticky. It had to be heat treated and cleaned before playback.
A spectrum from the original analysis for near-field passage of a ship was used to validate data recovery in the
range of 10500 Hz. A final objective is to produce calibrated time series so that the digital dataset can be made
available for general use. [Work supported by ONR.]
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October 1, 2004
Anderson Mills,
Department of Electrical and Computer Engineering,
The University of Texas at Austin
Topic: TBD
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October 8, 2004
John Goff,
Institute for Geophysics,
Jackson School of Geosciences,
The University of Texas at Austin
Topic: TBD
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October 15, 2004
Tom Yudichak,
Applied Research Laboratories,
The University of Texas at Austin
Topic: TBD
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October 22, 2004
Ruchi Goel,
Department of Electrical and Computer Engineering,
The University of Texas at Austin
Topic: TBD
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October 29, 2004
Speaker: TBD
Topic: TBD
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November 5, 2004
Speaker: TBD
Topic: TBD
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November 12, 2004
Ken Dickensheets,
Dickensheets Design Associates
Topic: TBD
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November 19, 2004
No Seminar: ASA Meeting
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November 26, 2004
No Seminar: Thanksgiving Break
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December 3, 2004
Tour of Acoustic Systems with William McKenna
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