Friday, April 3, 1998 4:00 p.m. Dr. Steven Grand Department of Geological Sciences The University of Texas at Austin http://www.geo.utexas.edu The Earth is a dynamic planet in which the plate tectonics is the surface expression of active flow in the deep mantle. Although the kinematics of plate tectonics is fairly well understood, the pattern of…
Friday, March 6, 1998 4:00 p.m. Professor Mark Hamilton and Ronald Kumon Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu Although nonlinear surface acoustic waves are the foundation for analog devices currently used to perform nonlinear signal processing operations, empirical models that describe these waves at moderate amplitudes were sufficient to advance…
Thursday, March 5, 1998 4:00 p.m. Dr John T. Post Applied Research Laboratories http://www.arlut.utexas.edu Thomas D. Kite Department of Electrical and Computer Engineering http://www.ece.utexas.edu and Professor Mark Hamilton Department of Mechanical Engineering The University of Texas at Austin http://www.me.utexas.edu In a parametric array, highly directional low-frequency sound is generated by the self-demodulation of an intense,…
Friday, February 27, 1998 4:00 p.m. Dr. G. Douglas Meegan Applied Research Laboratories The University of Texas at Austin http://www.arlut.utexas.edu This presentation will describe briefly several new acoustics research projects that are underway at Applied Research Laboratories. The common theme that links these projects is development of acoustical methods or technologies that are of potential…
Friday, February 13, 1998 4:00 p.m. Professor David Peterson Department of Mathematics University of Central Arkansas Conway, Arkansas http://www.uca.edu/divisions/academic/math/ http://www.uca.edu/ The hammered dulcimer, a predecessor of the piano, has a long and still evolving lineage. Some recent design changes follow from solid acoustical principles and others merely demonstrate the folk process at work. Several aspects…
Thursday, February 5, 1998 4:00 p.m. Professor Elmer L. Hixson Department of Electrical and Computer Engineering The University of Texas at Austin http://www.ece.utexas.edu By controlling the time delay and frequency function of each speaker in an array, the direction and coverage as a function of frequency can be controlled. Beamwidth can be held constant with…
Friday, January 23, 1998 4:00 p.m. Karen E. Hunt EVI Audio Austin, TX This seminar shall offer perspective on and direction in the profession of acoustical consulting. The general public is largely unaware of what acoustical consulting is, what acoustical consultants actually do, or how to become one. There are no comprehensive programs on a…
Friday, November 21, 1997 4:00 p.m. Dr. Brian J. Landsberger Center for Transportation Research The University of Texas at Austin http://www.utexas.edu/research/ctr The adverse effects of traffic noise are a serious concern both domestically and internationally. In many urban places, highways have been lined with noise barriers on one or both sides in an effort to…
Friday, November 14, 1997 4:00 p.m. Dr. Sally McInerny Department of Mechanical Engineering University of Alabama Tuscaloosa, Alabama http://www.me.ua.edu http://www.ua.edu In this presentation, known characteristics of rocket noise are reviewed. These include low peak frequencies, a high radiation efficiency and a large angle of peak directivity relative to that of subsonic and supersonic jets. The…
Friday, November 7, 1997 4:00 p.m. Stuart Rohre Applied Research Laboratories http://www.arlut.utexas.edu and Dr. Ronald Stearman Department of Aerospace Engineering & Engineering Mechanics The University of Texas at Austin http://www.ae.utexas.edu Both the Federal Aviation Administration and the Department of Defense are actively seeking methods of diagnosing structural conditions in aircraft. Although aircraft manufacturers have record…
Friday, October 31, 1997 4:00 p.m. Dawn Johnson Department of Zoology The University of Texas at Austin http://www.biosci.utexas.edu Animals frequently need to communicate with each other in order to reproduce successfully. Many species of birds, frogs, insects, and fishes communicate using acoustical signals. In fishes the structure of the signals and the selective pressures acting…
Friday, October 24, 1997 4:00 p.m. Dr. Mrinal Sen Institute for Geophysics The University of Texas at Austin http://www.ig.utexas.edu Seismograms recorded at the earth’s surface or in boreholes from earthquakes and manmade explosions are used extensively to infer the structure of the earth’s deep interior. Thus numerical modeling of seismic wave propagation plays an important…
Friday, October 17, 1997 4:00 p.m. Suzanne Richardson Schlumberger Austin, Texas http://www.slb.com Submarine sonar operators typically use video and monaural audio outputs to locate obstacles, ships, and animals in the vehicle’s path. Recently, the effectiveness of adding 3-D sound to sonar systems has been investigated. A system has been developed that converts sonar data collected…
Friday, October 10, 1997 4:00 p.m. Dr. Anthony Blackner and Dr. Belur Shivashankara Boeing Corporation Seattle, Washington http://www.boeing.com As air travel becomes more popular, the noise of airplanes for communities around airports has become a problem. If the impact of noise is to be diminished, the source levels have to be reduced. In this talk,…
Friday, October 3, 1997 4:00 p.m. Joe Norris American Technology Corp. San Diego, California http://www.atcsd.com This talk is a follow-up on the practical implementation of the parametric array in air. It will be shown that the original experiments of Hermann von Helmholtz, regarding the creation of difference frequencies-or Tartini tones-by sounding two tones loudly in…
Friday, September 26, 1997 4:00 p.m. Professor Elmer L. Hixson and Matias Budhiantho Department of Electrical and Computer Engineering The University of Texas at Austin http://www.ece.utexas.edu Probability density functions for acoustic fields in a reverberant space are developed. Acoustic pressure is a one degree-of-freedom random process while velocity is a three degree-of-freedom process. The higher…
Friday, September 19, 1997 4:00 p.m. Dr. Nicholas P. Chotiros Applied Research Laboratories The University of Texas at Austin http://www.arlut.utexas.edu Acoustic buried object detection by a dolphin was observed by means of a hydrophone placed directly above the object. Dolphins are known to be adept at locating prey and objects that are buried in the…
Friday, September 12, 1997 4:00 p.m. Professor David Blackstock Department of Mechanical Engineering Applied Research Laboratories The University of Texas at Austin http://www.me.utexas.edu “HyperSonic Sound” is American Technology Corporation’s commercial application of the parametric array to produce broadband audio sound ( Business Week , 12-2-96 issue, pp.108-109). E.G.Norris demonstrated the device at the Penn State…
Friday, April 11, 1997 4:00 p.m. Jack Evans, P.E. JEAcoustics Austin, Texas http://www.jeacoustics.com Commercial and industrial properties are often adjacent to residential properties. Land use compatibilities are poorly regulated in many communities, with neither rational noise zoning nor permissible continuous noise criteria in ordinances. Recent community noise issues in and around Austin will be discussed…
Friday, April 4, 1997 4:00 p.m. Robert D. Bruce Collaboration in Science and Technology, Inc. Houston, TX Acoustics and acoustical engineers have been at the center of attention in addressing some of our nation’s important legal problems. For example: Was the 18 minute gap in President Nixon’s dictaphone recording created deliberately or accidentally? How many…