News and Events


2013 年 05 月 07 日
Seminar - Sound Visualization by Prof. Yang-Hann Kim

Date:   07 May 2013 (Tuesday)

Time:   11:00 am – 12:00 pm

Venue:  EF305, The Hong Kong Polytechnic University


Ever since Louis Bertrand Castel tried to express the sound into color, there have been many attempts to transform sound in space in terms of visual impression. In this respect, acoustic camera or video seems to go in the right direction of development. Mathematically speaking, this is a typical inverse problem. This inverse problem generally depends on “the selected basis function, or the prediction model.” The prediction totally depends on how well the basis function mimics the entire data, not just the measured. One of common ways to classify the methods is to examine them with regard to the type of basis functions that are employed. One class can be regarded as the “non-parametric method” that uses the basis functions which do not model the signal. Orthogonal functions fall into this category. One of the typical methods of this kind is Fourier transform. Acoustic holography, in fact, uses this type of function: it maps the sound field of interest with regard to every frequency and corresponding harmonic functions. Another typical method is often called as “parametric method.” The name comes from the fact that the methods model the signal using certain parameters. The main issues that have been discussed for this kind of mapping methods are directly related to the correlation matrix structure that is simply the product of measured acoustic pressure vector and its complex conjugate. The scan vector is a basis function in this case. The signal to noise ratio of the measured correlation matrix also determines the effectiveness of the estimation. These issues will be examined in this talk.


Dr. Yang-Hann Kim received the BS degree from the Seoul National University in 1978, then received his Ph.D. degree from Massachusetts Institute of Technology in 1985 in the field of sound and vibration. On October of 1984, Dr. Kim joined the Department of Mechatronics of Korea Institute of Tech, Korea. He then moved to KAIST as an associate professor and became a professor in 1992. He is currently the Director of Center for Noise and Vibration Control(NOVIC), KAIST. He has written more than 300 journal, conference papers and book chapters in the areas of noise and vibration control, sound visualization, sound manipulation, including a recent acoustics textbook, “Sound Propagation: An impedance based Approach,” published by John Wiley and Sons, in 2010. Another book is about to be available, “Sound Visualization and Manipulation,” scheduled to be published on the coming June by the same publisher. Dr. Kim received several best paper awards from KSNVE, ASK, and ASA. He also delivered plenary lectures at inter-noise 2012, ICA 2004, and Keynote lectures at ICSV. He is a handling editor of MSSP, advisory board member of JSV, and NCEJ(Noise Control Engineering Journal). Dr. Kim is a fellow of ASA.