Yi-Wen Liu



Research [中文]

Updated in Apr 2016

My primary area is audio signal processing and the science of hearing. I am leading the Acoustics and Hearing Group (AHG) within the Graduate Institute of Electrical Engineering. Our current topics include:

Modeling of inner ear and auditory brainstem physiology: from basic science to clinical applications

Mammalian hearing (including humans) is sensitive to signals as weak as 10e-17 Watt.  For many years, scientists have studied its mechanisms, and found that "outer hair cells", a special kind of sensory cells located inside the cochlea, are responsible for amplification of acoustic signals.   These cells can convert mechanical energy and electrical energy in both directions, thus forming a positive feedback loop that acts as an amplifier. However, it is still debatable how this electro-mechanical feedback happens exactly.   My on-going research is to construct computer-based dynamic-system models from protein, cellular, to system levels, thus simulating nonlinear responses of both normal and pathological ears. This research in particular leads to better understanding of what is called otoacoustic emissions (OAE), i.e. sounds coming from the ear, and OAE can be used as a non-invasive, quantitative tool for the diagnosis and prognosis of various sorts of auditory pathology such acute hearing loss, Meniere's disease, and tinnitus. This research is currently collaborated with Dr. CK Chan (Inst. Physics, Academia Sinica), Dr. PC Wang (ENT, Cathay General Hospital, Taipei), and Dr. Vincent Wang (ENT, China Medical University Hospital).

Speech and audio signal processing

Part of the AHG concentrates on audio and speech signal processing, in particular pattern recognition and microphone array signal processing. Our main goal in recent years has been to develop acoustics-based monitoring system that can recognize unexpected events happening in private and public space. We believe that this technology can also be applied for healthcare purposes, such as to monitor a person's sleep quality by analyzing the snore sounds (s)he makes. 

Assistive hearing technologies

I am also interested in assistive hearing devices such as hearing aids or auditory prostheses (cochlear implant).  Because of global aging, I feel that it will become as common to wear these devices as wearing eye-glasses.  Assistive hearing technology still has a lot of room for improvement.  For instances, in a noisy environment, hearing aid users often couldn't hear comfortably; cochlear implants typically do not process pitch accurately, so users can't enjoy listening to music --- this is particularly problematic for communication in tonal languages, such as Mandarin, Vietnamese, etc.  With my expertise in this field, I hope to combine Taiwan's existing strength in electronic design and manufacturing and its high-quality medical practice so we can make contribution in the development of hearing technology and better serve those in hearing needs.

Other topics include music technology (score following/virtual musicians/optical score recognition), and other other biomedical applications of digital signal processing.