Abstract:

The conventional noise control technique (called passive noise control) has been working quite well for the mid- and high frequency range, typically through implementation of enclosures, barriers and silencers to absorb or block the acoustic waves. However, this technique tends to become very bulky and costly for a low-frequency noise since heavier and thicker materials are required for blocking the long-wavelength waves. Under this scenario, active noise control (ANC) technique was proposed in the 1930s, and has drawn widespread research interest in both academia and industry during the last two decades due to the fast development of digital signal processing devices. The fundamental concept of this new technique is to inject a secondary sound, via a control loudspeaker, that is out-of-phase with the primary noise such that the resultant sound pressure is canceled out or significantly minimized.

In the first part of this presentation, several active noise and/or vibration control projects that have been conducted in our lab will be briefly introduced. In particular, the implementation on vehicle interior powertrain and road noise control will be emphasized, where several state-of-the-art adaptive control algorithms have been proposed. For powertrain noise, it is primarily dominated by a large number of harmonics that are most perceivable when vehicle is at idle or changing speed conditions. Active powertrain sound quality control system is proposed to tune the engine noise spectrum since it normally reflects more information about the engine. In contrast, road noise is the dominant source when the vehicle is driving at middle or high speed, which is broadband colored noise and more fatiguing and irritating than having benefits. Thus, road noise must be well treated. In the second part of this presentation, a further-step study on the development of ANC system with more robust and efficient adaptive algorithms for treating impact acoustic noise will be presented. For example, many unwanted impact responses generated by punching machines, combustion engines and pile drivers as well as impact road noise due to road bumps. This type of noise may pose critical challenges for the prevalent adaptive control algorithms, which will further hinder the implementation of ANC system.

Biography:

Dr. Guohua Sun is currently a post-doc research fellow in mechanical engineering department at the University of Cincinnati (UC). Sun received his B.S. degree in mechanical engineering in 2006 from Shanghai Ocean University, and obtained his M.S. degree in mechanical engineering in 2009 from Tongji University. Shortly after his graduation from Tongji, he came to UC for his Ph.D. study in noise and vibration control, and graduated in September 2013. He has been working as a graduate research assistant at Prof. Teik Lim’s Vibro-acoustic and Sound Quality Research Laboratory since 2009, and has been primarily responsible for the active noise control project in collaboration with the Ford Motor Company. His current research focus is active noise control, vehicle NVH (noise, vibration and harshness) and structural-acoustic modeling. Sun is an active student member in SAE (Society of Automotive Engineers) and INCE-USA (The Institute of Noise Control Engineering of the USA).