Dr Youngsun Kim and his Proud Students

The Swallowing Research Lab (SRL) is located within the Communication Sciences and Disorders Division (CSD) at Ohio University (OU). Research at SRL primarily focuses on using objective analysis, such as temporal and biomechanical measures, to quantify characteristics of normal and disordered oropharyngeal swallowing in different populations and developing innovative intervention strategies for dysphagia rehabilitation. The director of the SRL is Dr. Youngsun Kim.  

Dr . Youngsun Kim, Ph D., CCC-SLP

Associate Professor

Communication Sciences and Disorders

School of Rehabilitation and Communication Sciences

Ohio University

Grover Center W233

Athens, OH 45701

E-mail: kimy2@ohio.edu



Ph.D.               2004                Speech and Hearing Sciences

                                                University of Tennessee

 M.A.               1999               Speech-Language Pathology

                                                University of Tennessee

 B.A.                1993                English as a Second Language Education

                                                Kangwon National University (South Korea)


Certificate of Clinical Competence:  American Speech-Language-Hearing Association (Certification Number: 12048773)

Ohio License: Speech Language Pathologist (License Number: SP. 8728)

 Refereed Publications

Kim, Y., Park, T., Oommen, E. & McCullough. G.H. (in press). Upper esophageal sphincter opening during the swallow in stroke survivors. American Journal of Physical Medicine and Rehabilitation.

Trent, A., Park, T., Oommen, E. & Kim, Y. (2014). The effects of bolus consistencies on the swallowing safety in poststroke patients, Communication Sciences and Disorders, 19(2), 249-255.

 McCullough, G. H. & Kim, Y. (2013). Effects of the Mendelsohn maneuver on extent of hyoid movement and UES opening post-stroke. Dysphagia. 28(4):511-519.

 Park, T, Kim, Y. & McCullough, G. H. (2013). Oropharyngeal transition of the bolus in poststroke patients, American Journal of Physical Medicine and Rehabilitation, 92(4), 320-326.

 Park, J, Kim, Y., Oh, J. & Lee, H. (2012). Effortful swallowing training combined with electrical stimulation in post-stroke dysphagia: A randomized controlled study. Dysphagia. 27(4), 521-7.

 Im, I, Kim, H., Ko, M, Oommen. E. & Kim, Y. (2012). Effects of bolus consistency in pharyngeal transit duration during normal swallowing, Annals of Rehabilitation Medicine.36, 220-225.

Oommen, E., Kim, Y & McCullough, G. H. (2011). Stage transition and  laryngeal closure in poststroke patients with dysphagia, Dysphagia.26.318-323.

Kim, Y., & McCullough, G. H. (2010). Maximal hyoid excursion in poststroke patients. Dysphagia.25. 20-25.

Park, T., Kim, Y., Ko, D., & McCullough, G. H. (2010), Initiation and duration of laryngeal closure during the pharyngeal swallow in patients poststroke. Dysphagia.25,177-182.

Kim, Y. (2009). Temporal and biomechanical measurements of upper esophageal sphincter (UES) opening in normal swallowing. Korean Journal of Communication Disorders.14(1), 108-114.

 Kim, Y., & Park, Y. (2008). Biomechanical measurement of hyoid excursion during the swallow: a pilot study, Korean Journal of Communication Disorders, 13(3), 503-512.

 Kim, Y., & McCullough, G. H. (2008). Maximum hyoid displacement in normal swallowing.  Dysphagia, 23, 274-279.

 Kim, Y., & Park, T. (2007). Age and gender differences of laryngeal closure duration  in normal swallowing, Korean Journal of Communication Disorders,12, 521-531.

 Kim, Y., & McCullough, G. H. (2007). Stage transition duration in patient poststroke, Dysphagia, 22, 299-305.

Kim, Y., McCullough, G. H., & Asp, C. W. (2005). Temporal measurement of pharyngeal swallowing of normal adult populations. Dysphagia, 20, 290-296.

            Kim, Y., & Asp, C. W. (2002). Low frequency perception of rhythm and intonation speech patterns by normal hearing adults. Korean Journal of Speech Sciences, 9, 7 -16.

Research Areas

Biomechanical Analysis of Oropharyngeal Swallowing

Biomechanical analysis involves measuring distances moved by anatomical structures in the oral and pharyngeal stages of swallowing. Examples of such measurements would include vertical and anterior displacement of the hyoid and larynx, maximum opening of the upper esophageal sphincter (UES), etc. Such measurements are identified by frame-by-frame analysis of X-ray studies (VFSE) of swallowing. Research at the SRL primarily focuses on recording such biomechanical measurements, specifically those looking at hyoid, laryngeal, and UES movements, and comparing differences between healthy adults and stroke patients. In addition, the effects of bolus characteristics such as consistency and volume on biomechanical measurements are examined.

                Vertical and Anterior Displacement of the Hyoid

The distance in centimeters of the hyoid bone’s maximum displacement both vertically and anteriorly. It is measured by the difference between the hyoid at rest and the hyoid at maximum vertical/anterior displacement.

               Vertical and Anterior Displacement of the Larynx

               The distance in centimeters of the larynx’s maximum displacement both vertically and anteriorly. It is measured by the difference between                                the larynx at rest and the larynx at maximum vertical/anterior displacement
                                Examples of the hyoid and larynx at rest and at maximum superior anterior displacement

Maximum Opening of the Upper Esophageal Sphincter (UES)

               The distance in centimeters of the maximum opening of the UES 


Temporal Analysis of Oropharyngeal Swallowing

Temporal analysis involves recording timing of physiological events and mechanisms that occur during oropharyngeal swallowing. A few examples of temporal measurements from the oral and pharyngeal stages are oral transition time (OTT), pharyngeal transition time (PTT), stage transition duration (STD), laryngeal closure duration (LCD), and duration of UES opening (DUESO). Similar to the biomechanical analysis, these measurements are also obtained from frame-by-frame analysis of X-ray studies. At the SRL, research examining the effects of age, gender, intervention strategies, bolus consistency, and bolus volume on temporal measures in healthy adult and stroke populations has been of particular interest.

Oral Transition Time (OTT)

The time it takes for a bolus, or a cohesive piece of material ready to swallow, to move through the oral cavity to the pharynx. It is measured from the initiation of backwards movement of the bolus by the tongue (position a) to the bolus head passing the ramus of the mandible (position b) on the VFSE (Logemann, 1986). Would be calculated as

OTT = a – b  


 Pharyngeal Transition Time (PTT)

The time it takes for the bolus to move through the pharyngeal cavity to the esophagus. It is measured from the bolus head passing the ramus of the mandible (position b) to the bolus tail passing through the Upper Esophageal Sphincter of the Esophagus (position c) (Logemann, 1986) Would be calculated as PTT = b – c

                                                                 Reference points for measurements in Oral and Pharyngeal Transition Times

Stage Transition Duration (STD)

The time difference between the bolus first passing the ramus of the mandible and the onset of hyoid excursion (Robbins, Hamilton, Log, & Kempster, 1992).

Laryngeal Closure Duration (LCD)

The time between the first contact of the arytenoids and the epiglottis and the last contact between the  arytenoids and the epiglottis ( Logemann, Pauloski, Rademaker, & Kahrilas, 2002).

Duration of Upper Esophageal Sphincter Opening (DUESO)

The time between the initial opening and closure of the UES ( Robbins, Hamilton, Log, & Kempster, 1992).