This project is a first attempt to assess cough airflow dynamics and true vocal fold (TVF) adduction and abduction angles during voluntary cough to examine the effects of changes in glottal closure due to reduced mobility of one true vocal fold. The hypothesis of this study is that the incomplete glottal closure due to reduced vocal fold mobility will result in changes in true vocal fold adductory and abductory angles during cough and will result in changes to voluntary cough airflow parameters. This study results will contribute to the existing knowledge of the laryngeal contribution to cough airflow dynamics.

The study investigators will consecutively recruit 30 adults diagnosed with vocal fold insufficiency due to reduced mobility of one true vocal fold.

A questionnaire will be used to collect participants' information. Demographic information such as age, gender, race/ethnicity, height, weight, and a major complaint (dysphonia and/or dysphagia) and medical history information determining the eligibility for participation will be collected from the participant. Participant's medical and surgical history specifically related to the diagnosis and the etiology of reduced vocal fold mobility will be obtained from the participant's medical record.

Videolaryngoscopy will be performed as part of standard clinical care. Vocal fold image and cough airflow will be recorded simultaneously during voluntary cough production with the flexible endoscope in nasopharynx. A second part of the study will include spirometry and expiratory muscle strength assessments. Video images of the vocal fold movement during vowel phonation and cough production will be recorded and stored on a CD for later analysis. The cough airflow recordings will be displayed, stored, and analyzed using LabChart software for Windows.

Inclusion Criteria:

1. Age between 40 and 75 years.
2. Glottal insufficiency secondary to reduced TVF mobility confirmed with the endoscopic evaluation performed by an otolaryngologist.
3. The ability to provide informed consent.
4. No history of chronic obstructive pulmonary disease, lung cancer, and/or lung transplant.
5. No history of neurodegenerative disease such as Parkinson's disease, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), or progressive supranuclear palsy (PSP), Alzheimer's disease, or dementia.

Exclusion Criteria:

1. Chest infection within one month prior to the study participation.
2. History of the adverse reaction associated with laryngoscopy.

The participants will represent a population of patients with glottal insufficiency due to unilateral true vocal fold immobility.