Welcome to the webpage for the Laryngeal Physiology Laboratory at the University of Wisconsin-Madison.
Our expertise is in signal processing, computer modeling, and instrumentation.
Our Principal Investigator and Director is Dr. Jack Jiang, who is also the Director of International Collaborative Research and Translational Research for the Department of Surgery, and the Director of the Otolaryngic Biomedical Engineering Research Center. He is widely published in the area of voice measurement and disorders, and serves on the editorial boards for the Journal of Speech, Language, and Hearing Research, the Journal of Voice and for Annals of Otology, Rhinology, and Laryngology. He has served on Study Sections for the Center for Scientific Review of NIH since 1998, and he is a 2001 recipient of a Presidential Early Career Award for Scientists and Engineers.
Our main areas of research include:
Voice disorders impact the lives of millions of Americans, leading to difficulties performing work duties, communicating with family and friends and often reducing engagement in social activities. Evaluation of voice quality is necessary to identify problems and track treatment. Voice assessment can be invasive or non-invasive, subjective or objective. Acoustic voice analysis benefits from being both non-invasive and objective. Unfortunately, acoustic analysis has been plagued with inconsistencies and is often unreliable when applied to increasingly severely disordered voices. Numerous factors impact the results of acoustic analysis; by evaluating these factors we endeavor to define a protocol that will generate more consistent results. Our work also endeavors to develop and validate analysis procedures that are more robust and capable of describing severely disordered voices.
Excised larynx research focuses on physically modeling phonation in a controlled setting. By varying the physical parameters of the larynx, we can test hypotheses of physiology and pathophysiology. An ex vivo animal larynx is connected to the system to simulate the respiratory system. Aerodynamic measures (e.g. pressure, flow) of the input into the larynx are recorded. Simultaneously, measurements of the state of the larynx and its output (e.g. acoustics, high-speed digital imaging of vocal fold movement) are recorded. By combining aerodynamic, acoustic, and high-speed imaging measurements, a highly descriptive model of the state of the larynx during phonation can be recorded. Changes in biomechanical properties of the larynx as seen in laryngeal diseases can then be induced to observe how these changes affect phonation.
Glottal Image Analysis
Spatiotemporal research examines the movement of the vocal fold mucosa through space over time. The parameters of amplitude, frequency, and intra- and inter-vocal fold phase differences are all sensitive to changes in the respiratory system, including air flow, pressure, humidity and glottal configuration. High-speed digital video is used to record the movements of the vocal folds during phonation. The vibratory properties of each of the four vocal fold lips (right-upper, right-lower, left-upper, left-lower) can be quantified via digital videokymography (VKG), a line-scan imaging technique. Threshold-based edge detection, manual wave segment extraction, and non-linear least squares curve fitting using the Fourier Series equation can then be applied to the VKG to determine the most closely fitting sinusoidal curve. High-speed digital video is an improved method of mucosal wave analysis because it allows for real-time visualization of the mucosal wave. Characterization of the mucosal wave in larynges provides a useful diagnostic tool for various laryngeal pathologies and a method of evaluation for their respective treatments.
Aerodynamics of phonation
Our aerodynamics research focuses on the development on new devices which can noninvasively measure the inputs to phonation. These measurements allow a clinician to determine the effort required to produce voice. Such parameters provide objective, quantitative, and valuable information not offered by common clinical tests such as stroboscopy or perceptual acoustic evaluation. Currently, we are developing three different devices for aerodynamic assessment: the airflow interrupter; the incomplete airflow interrupter; and the airflow redirector. All devices have been previously demonstrated to be valid, but are not yet widely used in the clinic. By demonstrating the effectiveness of these devices in distinguishing normal from disordered voice production and also making them easier to use, we aim to make aerodynamic assessment a routine aspect of any voice evaluation.
Current swallowing evaluation is performed by looking at single pressure points. However, swallowing deficiencies usually results from a more global problem. Our lab has been working on methods to globally analyze the pressure traces obtained from patients during swallowing. Performing this global pattern recognition has the potential to be a more efficient and effective method of characterizing disordered swallowing in the clinic.
Surgery training is an important part of a surgeon’s education. We are developing a system to quantify the motion of both the phonosurgeon’s hands as well as the surgery tools using motion capture technology. Together with a previously created phonosurgery dissection station and use of both simulated and excised tissue, we are creating a system of surgical training that allows phono surgeons to practice their skills without putting patients at risk.