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times of sonic booms in the presence of both kinematic and thermal turbulence in the atmosphere. Using laboratory scale measurements of N waves they showed that turbulence usually increases rise times and decreases the overpressure. However, because of random focusing, the peak pressure can be increased, and this should be accounted for in determining the loudness of sonic boom. Blanc-Benon also showed that during turbulent conditions ground roughness can substantially affect the peak pressures and rise times compared with the usual flat-ground assumption.
• Lou Sutherland presented a paper along with his colleagues Karl Kryter and Joe Czech reminding the ISBF participants that any acceptability criteria for supersonic aircraft will have to account for building vibration and startle. Sutherland indicated that pre- vious studies have shown that building vibration and rattle are the “most annoying” aspect of traditional sonic booms, and that startle is the “most disturbing” aspect. Although industry intends that their new “low-boom” aircraft will neither be annoying nor startling, these were sobering words of wisdom for the ISBF attendees.
• Brenda Sullivan of NASA Langley Research Center reviewed some of the known results from the High Speed Civil Transport studies of the 1990s regarding the human perception of sonic boom as well as some results found recently. She noted that earlier results indicating that peak overpressure does not correlate with subjective loudness is still true. For the low-level booms now envisioned by industry, calculated loudness (Steven's Mark VII) and A-weighted metrics are quite adequate and work with complex, multi-shock waveforms as well as sim- ple waveforms. Another of Sullivan’s recent research results is that post-boom noise, the rumble after the main boom sound, seems to be very important for sonic booms to sound “realis- tic” upon playback in sonic boom simulator boxes. Sullivan also reported some of the subjective experiments recently car- ried out by members of the PARTNER Center of Excellence, described earlier.
• Joe Salamone of Gulfstream Aerospace Corporation described his company's Supersonic Acoustic Signature Simulator II (SASSII), a portable unit inside a trailer that can be towed to any desired location. It contains high-fidelity audio equipment capable of playing both recorded and synthesized sonic boom signatures. In fact, the SASSII was available throughout the ISBF and ISNA17 for participants to hear comparisons between the sonic boom of Concorde and that of an envisioned low-boom aircraft.
• Nicolas Epain of Laboratoire de Mechanique et d’Acoustique in Marseilles, France presented work on another sonic boom sim- ulator, this one using 3-D sound field reproduction. They included spatial orientation of the sonic boom by arranging realistic wave front passage by the listener.
In addition, the panelists making short presentations included Laurie Fisher of the FAA, Ken Orth of Gulfstream Aerospace Corp., Akira Murakami of the Japanese Institute of Space Technology and Aeronautics (JAXA), Gerard Duval (a retired Concorde pilot), Thierry Auger of Airbus, Sam Bruner of Raytheon, Tom Hartmann of Lockheed-Martin Aeronautics, and Richard Smith of NetJets, Inc.
Victor W. Sparrow is Associate Professor of Acoustics at The Pennsylvania State University. He received his Ph.D. in 1990 from the University of Illinois, Urbana-Champaign, and joined Penn State’s Graduate Program in Acoustics that year. In 1996 he received the ASA R. Bruce Lindsay Award, and was elected
an ASA Fellow in 1998. He currently serves on the ASA Executive Council and is Project Lead for the PARTNER Center of Excellence Sonic Boom Mitigation Project. In addition to sonic booms his research interests include physical acoustics, structural acoustics, computational acoustics, virtual acoustics, and acoustic visualization.
6,862,360
43.38.Ja SPEAKER SYSTEM
Jen-Hui Tsai, Wen Shen Suburb, Taipei, Taiwan, Province of China
1 March 2005 (Class 381/351); filed 19 April 2001
A novel understanding and interpretation of the laws of physics, how electrodynamic loudspeakers and their constituent parts operate, the why and how of enclosure and port design, among other things, lead to an interesting patent that is an excellent example of wishful thinking. The patent basically describes a plurality of volumes 14 and ports 20, each tuned to a different frequency band, that solve a multiplicity of problems, none of which are adequately described.—NAS
28 Acoustics Today, January 2006