Meeting Announcement: Dr. Uwe J. Hansen to Speak on Phase Considerations in Signal Processing

The Central Indiana Section of the Audio Engineering Society is pleased to announce that Dr. Uwe J. Hansen will speak on Phase Considerations in Signal Processing at our May 2011 meeting.

Dr. Hansen is Professor Emeritus of Physics at Indiana State University and a fellow of the Acoustical Society of America, among numerous other distinctions.

The meeting will be held in the conference room of ESCO Communications Indianapolis office. We also hope to offer a live web stream of the event, however, those able are encouraged to attend. To ensure an accurate count for the meeting, please RSVP below.

Live Stream Info
Due to a software issue, a live stream will not be available for this meeting, However, a video recording will be available online in short order. Please check back in the coming days. We appreciate the patience shown as we deal with a these technical issues.

Topic Abstract
The essential elements in describing a monochromatic wave are: amplitude, frequency, wavelength, speed of propagation, polarization and phase. Any interrelation between these characteristics is mostly determined by the interaction of the wave with the medium in which it travels. Thus dispersion relates to the frequency dependence of the propagation speed.

Amplitude, for example, is related to loudness in sound and brightness in light. Frequency or wavelength on the other hand relates to color in light and pitch in sound. Polarization considerations are limited to transverse waves such as electromagnetic waves or bending waves in structural vibrations. Phase identifies the location of a point along the propagating waves. Absolute phase measurements are not only difficult but generally not of interest.

Phase comparison, on the other hand is a powerful tool. The most obvious application is in active noise control, such as noise canceling head sets. Three applications of phase related signal processing techniques will be discussed: 1. Phase sensitive detection which is used to enhance signal to noise ratios in weak signals. 2. Optical holography, which relies entirely on phase comparison of coherent signals, and 3. Modal analysis, used to study normal mode vibration in structural systems.

About Dr. Hansen
With a Ph.D. in Low Temperature Solid State Physics from Brigham Young University, Dr. Uwe J. Hansen  joined the physics faculty at Indiana State University in 1968, after a post-doctoral fellowship at the US Naval Research Laboratory. Most of his work since then has been in the field of Musical Acoustics with emphasis on structural vibrations in musical instruments such as hand-bells, guitars, violins, piano sound boards, and Caribbean steel pans.

The tools he has used include holographic interferometry, modal analysis, and finite element analysis. He has lectured world-wide, has served as president of the Indiana Academy of Science, chairman of the Physics department at ISU and is currently serving as Executive Director of CSUI, and editor of the Proceedings of the IAS. As a fellow of the Acoustical Society of America he continues to do research and teach at ISU, though now retired.

To stay up to date on section activities, be sure to follow us on Facebook or Twitter, and feel free to contact any member of the executive board to let us know your thoughts about the section.