The size and pressure / volume relationship (compliance) of the pharynx are considered important factors in pathogenesis of obstructive sleep apnea.Acoustic pharyngometry has the potential for assessment the size and compliance of the pharynx.Accurately detection of the site (s) of obstruction or narrowing of the pharynx in obstructive sleep apnea patients is important issue to manage them successfully. By acoustic pharyngometry, it is easy to assess the possible level (s) of obstruction.