Practical Studies of the Impact of Environmental Noise

Friday, April 10, 1992 4:00 p.m. Jack B. Evans, P.E. Jack Evans & Associates, Inc. Engineered Vibration Acoustic & Noise Solutions Building design criteria and construction parameters, with a focus on environmen­tal noise from mechanical equipment, including engineer generators, fire pumps and cooling towers will be presented. Case histories will be discussed, includ­ing on-site observations…

Second Harmonic Generation in a Focused Sound Beam that is Reflected and Transmitted at a Curved Interface

Friday, April 3, 1992 4:00 p.m. Inder Makin Biomedical Engineering The University of Texas at Austin The talk will present a model for second harmonic generation in a focused Gaus­sian beam that is reflected and transmitted at a slightly curved interface. Second harmonic generation is a nonlinear effect that accompanies waveform distortion at sufficiently high…

N Wave Propagation through Turbulence as Scale Model of Sonic Boom Propagation through the Atmosphere

Friday, February 21, 1992 4:00 p.m. Bart Lipkens Applied Research Laboratories and Department of Mechanical Engineering The University of Texas at Austin Typical measured sonic boom rise times are two to five times longer than rise times calculated using molecular relaxation theory [J. Kang, Ph.D. thesis, Pennsylvania State University (May 1991); A. D. Pierce and…

Nonlinear Acoustics: Analogs of Phenomena in Nonlinear Optics

Friday, January 31, 1992 4:00 p.m. Dr. Mark F. Hamilton Department of Mechanical Engineering The University of Texas at Austin Although the study of nonlinear acoustics predates nonlinear optics by more than a century, nonlinear optics has been exploited much more for technological applications than has nonlinear acoustics. The main differ­ence is dispersion (dependence of…

On the Use of Acoustic Cues to Aid Pilot Orientation

Monday, December 2, 1991 3:00 p.m. D. C. Teas KRUG Life Sciences, Inc. and Kent K. Gillingham Armstrong Laboratory, Brooks AFB, TX Spatial disorientation accounts for a substantial percentage of aircraft acci­dents and nearly all such accidents are fatal. Pilots also report experiencing disorientation during flight without losing control of their aircraft. When disorientation is…

A General Method for Determining Arbitrary Acoustical Impedances

Monday, November 18, 1991 3:00 p.m. John Post Electrical & Computer Engineering Department The University of Texas at Austin To study the throat impedance of a JBL constant directivity horn, a new acoustic impedance measurement system has been developed. This system will be presented along with supporting data from the horn measurements. Additional applications will…

Acoustical Characterization of Seafloor Sediments: Geoacoustic Description of Bubbly Sediment Samples

Monday, October 14, 1991 3:00 p.m. Aubrey L. Anderson Department of Oceanography Texas A & M University Remote sensing characterization of seafloor sediments with acoustic sys­tems is a long standing goal of acoustical oceanographers. Recent results of measurements with side scan sonars and chirp sonars are encouraging. A major complication in the interpretation of such…

A Broadband, Constant Beamwidth, Near Field Receiving Array or “No Hands” Cellular Phone

Monday, October 7, 1991 3:00 p.m. Noel A. Adorno and E. L. Hixson Department of Electrical and Computer Engineering The University of Texas at Austin A focused microphone array in the headliner of a car could provide a “no hands” cellular system microphone. The usually installed stereo could pro­vide the receiver. The focal volume should…

Physical Acoustics and Relaxation

Friday, September 20, 1991 12:00 p.m. Dr. Timothy S. Margulies U.S. Nuclear Regulatory Commission Washington, D.C. The theoretical prediction of acoustic wave propagation in fluids is im­portant for understanding medical diagnostic techniques, ocean and other geophysical transmission characteristics; as well as, for measuring physio­-chemical properties of fluids, and for estimating equations of state. The purpose…

Nonlinear Acoustic Wave Propagation in a Pekeris Waveguide

Thursday, September 19, 1991 1:00 p.m. Carl Bruch Department of Physics The University of Texas Although acoustical media are often stratified, either continuously (e.g., via sound speed gradients) or with discrete but penetrable layers, finite amplitude effects in stratified media have been all but ignored. By channeling the sound, however, stratification can maintain high acoustic…