Otolaryngology /ˌoʊtoʊˌlærɪŋˈɡɒlədʒi/, is the study of ear, nose, and throat conditions or ENT. It is also referred to as Otolaryngology-Head and Neck Surgery or Otorhinolaryngology. It is the oldest medical speciality in the United States, where nearly 50 percent of all office visits pertain to the ear, nose, and throat. Physicians specializing in otolaryngology are called otolaryngologists or by the nickname "ENTs" or "ENT doctors" and often treat children with persistent ear, nose, and throat conditions to include surgery. Adult patients often seek treatment from an otolaryngologist for sinus infections, age-related hearing loss, and cancers of these regions. Otolaryngologists are physicians (MD, DO, MBBS, MBChB, etc.) who, in the United States, complete at least five years of surgical residency training. This is composed of one year in general surgical training and four years in otolaryngology–head and neck surgery. (In the past it varied between two and three years of each.) In Canada, practitioners complete a five-year residency training after medical school. Following residency training, some otolaryngologists complete an advanced sub-specialty Fellowship where training can be 1–2 years in duration. In the United States, otolaryngology is one of the most competitive specialties in medicine in which to obtain a residency position following medical school.