<prompt> Which of the following is the gold standard test for Laryngopharyngeal Reflux?24 hour double probe pH monitoringEsophageal biopsyAbnormal esophageal radiography BariumSwallowEsophageal motility studies  <response>: Currently, the Gold standard test for Laryngopharyngeal Reflux is 24 hour double probe pH monitoring. An arbitrary threshold of pH4 is used to diagnose reflux whether at the esophageal probe 5 cm above the lower esophageal sphincter for gastroesophageal reflux or at the pharyngeal probe 2 cm above the upper esophageal sphincter for laryngopharyngeal reflux LPR. 