Velopharyngeal insufficiency (VPI) occurs when the sphincter between your oral and nasal cavities doesn’t close completely. It can make your voice sound nasally or cause speech problems. In severe cases, solid foods or fluids may regurgitate (come up) through your nose. VPI is a type of velopharyngeal dysfunction. It involves the velopharyngeal sphincter, the juncture between your: Nasopharynx, the upper part of your throat (pharynx) that’s behind your nose. Oropharynx, the middle part of your pharynx that’s behind your mouth. A sphincter is a ring of muscle that protects or closes an opening or tube in your body. The velopharyngeal sphincter is active when you swallow or speak.