Our lab focuses on signal processing, computer modeling and instrumentation. Along with basic science research, we contribute to the advancement of technologies for ears, nose and throat (ENT) medicine.
Specialty Areas
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Acoustics
Voice disorders impact the lives of millions of Americans, leading to difficulties in performing work duties, communicating with family and friends and engaging in social activities. Clinicians and researchers evaluate voice quality in order to identify problems and track treatment. Voice assessment can be invasive or noninvasive, subjective or objective. Acoustic voice analysis benefits from being both noninvasive 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 aims to develop and validate analysis procedures that are more robust and capable of describing severely disordered voices.
Laryngeal Models
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 of new devices that 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. We are developing three different devices for aerodynamic assessment: the airflow interrupter; the incomplete airflow interrupter; and the airflow redirector. All devices have been validated, but are not yet widely used in the clinic. By demonstrating the effectiveness of these devices in distinguishing normal from disordered voice production and making them easier to use, we aim to make aerodynamic assessment a routine aspect of any voice evaluation.
Phonosurgery Training (Inactive)
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 the use of both simulated and excised tissue, we are creating a system of surgical training that allows phonosurgeons to practice their skills in a risk-free environment.
Swallowing
Current swallowing evaluation is performed by looking at single pressure points. However, swallowing deficiencies usually result from a more global problem. Our lab has been working on methods to globally analyze the pressure traces obtained from patients during swallowing. Global pattern recognition has the potential to be a more efficient and effective method of characterizing disordered swallowing in the clinic.
Biomedical Engineering ENT Center
The Jiang lab contributes to the advancement of technologies for ears, nose and throat (ENT) medicine through the Biomedical Engineering ENT Center. We develop devices to treat and evaluate disorders, as well as parameters that measure physiological function and diagnose disorders.
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Pharyngeal High-Resolution Manometry
The Adjustable Balloon Implant, 2011
(with Timothy M. McCulloch, MD)
We present the adjustable balloon implant (ABI), a novel implant to be used in type I thyroplasty for the treatment of vocal fold paralysis. The ABI offers the same medialization provided by other implants, but can easily be catered to individual patient anatomy as well as modified postoperatively without the need for a revision thyroplasty.
A round balloon with diameter of 12 mm and wall thickness of 0.5 mm was connected via tubing to a luer slip one-way check valve on an implant manufactured by Hood Laboratories (Pembrooke, MA.) The tubing had an outside diameter of 1.5 mm. Both the balloon and tubing were made using 50 durometer medical grade silicone. The implant was placed lateral to the thyroarytenoid muscle and secured inside the larynx using an aluminum frame. Although aluminum was used in the preliminary study on excised canine larynges, the frame would be manufactured from titanium if the implant were applied to human patients.
Superior and inferior flanges prevented extrusion of the implant while lateral flanges with holes allowed the frame to be sutured to the thyroid lamina. A balloon with maximum volume of 1.5 cc was used for all excised canine larynges. The selected size was based on knowledge of volume required for effective injection laryngoplasty, with added volume to compensate for the manipulations to the larynx made when creating the thyroplasty window. A main advantage of the ABI is that the size of the balloon is not as important as the volume of saline injected into it. Although only one implant was used in this study, it worked for a variety of larynges. The amount of saline injected depended upon the size of the larynx and width of the glottal gap. Saline was injected into the balloon via a luer slip syringe until the paralyzed fold approximated the normal fold. Fine adjustments were then made according to perceptual analysis of vocal quality and quantitative analysis of threshold aerodynamics. Care was taken to avoid overinjection and resultant balloon bulging. If bulging was observed, saline was removed until an optimal volume was reached.
Excised dog larynx with balloon filled with 1.2 cc saline.
Kymograms from one larynx for the three experimental conditions: normal (A); simulated vocal fold paralysis (B); and the adjustable balloon implant©.
Optimal Arytenoid Adduction
Optimal Arytenoid Adduction Based on Quantitative Real-Time Voice Analysis, 2011
(with Timothy M. McCulloch, MD)
Unilateral vocal fold paralysis (VFP) was modeled in five excised canine larynges. Medialization laryngoplasty (ML) was performed, followed by AA. The optimal degree of arytenoid rotation was determined using real-time measurements of vocal efficiency (V(E) ), percent jitter, and percent shimmer. After the optimal degree of rotation was determined, the arytenoid was hypo- and hyperrotated 10% ± 2% of the optimal angle to mimic hypoadducted and hyperadducted states. Aerodynamic, acoustic, and mucosal wave measurements were recorded. Mean optimal angle of arytenoid adduction was 151.4 +/- 2.5. The arytenoid was then hypo- and hyperrotated to mean angles of 161.6 +/- 11.2 and 143.4 +/ 13.5, respectively. Optimal AA was found to greatly improve percent jitter and shimmer when compared to other treatments (ML, hypo-AA, hyper-AA). Using real-time voice analysis may aid surgeons in determining the optimal degree of arytenoid rotation when performing AA.
We expanded upon recently introduced teaching paradigms in laryngology by developing a model for laryngeal education that was readily available, inexpensive, and provided an experience similar to in vivo human laryngeal surgery. A temporal bone lab was modified into a laryngeal dissection lab with minimal changes. Canine larynges were found to strongly resemble human larynges and were easily used in a teaching model. They were more easily acquired and less expensive than human larynges. A novel dissection approach was created to maximize utility of a single cadaveric laryngeal specimen. A laryngeal dissection course with specific teaching objectives was formulated, which led to the creation of a laryngeal dissection manual.
Mucosal Wave Analysis
Mucosal Wave Analysis, 2008, 2010
(with Yu Zhang, PhD)
The mucosal wave is a property of vocal fold vibration characterized by the alternating mediolateral motion of the upper and lower vocal fold lips. Subglottal pressure against the lower vocal fold lips causes them to open and move laterally, and when the pressure continues upward, the upper vocal fold lips open. The decrease in pressure in the subglottal space following the vertical release of air during the opening of the upper vocal fold lips pulls the lower vocal fold lips closed in the medial direction. This is followed by the closing of the upper vocal fold lips as well (Krausert et al., 2010). These successive movements of the upper and lower vocal folds are facilitated by the pliability of the mucosal epithelium and upper lamina propria, and they resemble a vertically traveling wave. Thus, this feature of vocal fold vibration is termed the mucosal wave.
VKG, a line-scan imaging technique, has proven to be an effective method for studying vocal fold vibratory patterns. We used VKG images and an automatic mucosal wave extraction method to examine the vibration of each individual vocal fold lip of 17 excised canine larynges under differing subglottal pressures and line-scan positions. This allows for easy determination of four sets of vibratory parameters, and examination of the effect of biomechanical parameters on vocal fold vibrations.
Incomplete Airflow Interruption
Recently, airflow interruption methods have shown the most promise as simple, noninvasive techniques to estimate SGP. Our previous airflow interruption system did not estimate SGP during phonation but during a period just after phonation ceased. Studies have suggested that estimating SGP at the moment phonation ceases may not represent the true value of SGP as it exists during normal phonation. In addition, completely blocking airflow during phonation (especially at higher intensity levels) might be a disruptive stimulus, potentially inducing inadvertent changes in subject phonation and glottal configuration. We developed a new noninvasive method to estimate SGP that was less disruptive and did not completely interrupt phonation. Using incomplete airflow interruption by way of supraglottal impedance (pneumatic resistors), we estimated SGP(cmH2O) from measured airflow (L/s) and known supraglottal impedances (cmH2O/L/s) by applying the predictable relationships between pressure, flow, and resistance.
Chaotic Systems
Using Nonlinear Dynamic Analysis in Chaotic Systems
(with Yu Zhang, PhD; ZongXi Zhao; Charles N. Ford, MD)
“Chaos” is a term that describes pseudorandom behavior generated by a system that is both deterministic and nonlinear. Although chaos was once thought to be unique, it has now been widely observed, such as in turbulence, chemical reactions, nonlinear circuits, the solar system, and biological populations. Studies in neurology and cardiology suggest that chaotic activity is an important aspect of physiologic systems. Methods based on nonlinear dynamics, including general dimension (Hausdorff dimension, information dimension, correlation dimension, etc.), entropy (Kolmogrov entropy, second-order entropy, etc.), and Lyapunov exponents, enable us to quantitatively describe chaotic behavior. Chaos theory and nonlinear dynamics can enhance our understanding and therefore our assessment of pathological phonation.
Airflow Interruption System
Airflow Interruption System, 1999
(with Liang Zhou, MD; David Conley, MD; David Hanson, MD)
Phonation threshold pressure (PTP) is theoretically defined as the minimum subglottal pressure (SGP) that is necessary to sustain phonation for a given laryngeal configuration. Mathematical models and animal studies predict that PTP should be increased when phonation is abnormal due to vocal fold disease. A measure of PTP might therefore provide a useful measure of the ease with which phonation is produced, and such a measure might be clinically useful in the evaluation of clinical voice disorders.
We developed an airflow interruption system to allow noninvasive estimation of PTP at different levels of vocal intensity. Subjects sustain a constant tone and the airflow is directed into a section of pipe with an airtight mask over the mouth and nose. The airflow, intramask pressure, and intensity of the acoustic output are recorded. A PTP is predicted from a difference between an estimate of the subglottal pressure and the vocal tract pressure at the point that phonation ceased after interruption of airflow.
Lab Staff
Jack J. Jiang
Credentials: MD, PhD
Position title: Professor; Voice Research Training Program Co-Director
Email:
jjjiang
Undergraduates
Ashmita Bhowik – biomedical engineering
Ashvath Madhushankar – neurobiology
Brady Prosser – neurobiology
Brynn McCloskey – biochemistry and data science
Colin Conley – biochemistry
Elise Moreira – neurobiology
Elle Heimer – biomedical engineering
Ellie Osberg – biology
Jakob Holm – biochemistry
Kelly Shih – data science
Maiwand Tarazi – biochemistry
Melina Peters – neurobiology
Michael Kuang – mechanical engineering and chemistry
Penelope Gobes – neurobiology
Rohit Srivatsav Raghunathan – biomedical engineering
Sathviga Ravi Shankar – global health
Serena Gacek – biology
Sylvia Green – global health
Varsha Gourham – data science