Pharyngeal pH monitoring is a test used to evaluate for effects from gastroesophageal reflux disease that could be affecting the throat and result in swallowing, breathing, or voicing problems. This test measures the amount of acid that is refluxed into the throat while the probe is in place. It involves the placement of a tiny probe into the throat that is worn over a period of time. You can breath, talk, eat, and sleep with the probe in place, as it is meant to capture the amount of acid your throat is exposed to during a regular day. Depending on the clinical questions to be answered, the test may include wearing the probe 24-hour or 48-hour period of time. The pharyngeal pH probe is different than an esophageal pH study, which measures acid exposure in the esophagus alone, and not the pharynx. The pharyngeal pH probe is also different from an esophageal Bravo pH study, which also measures acid exposure in the esophagus alone.