Upper gastrointestinal symptoms and diseases, specifically dyspepsia and acid reflux are common problems faced by the adult U.S. population. These symptoms frequently necessitate an upper gastrointestinal endoscopy, which is performed to rule out anatomic diseases. Moreover, these symptoms can be associated with complications such as erosive esophagitis, Barrett's esophagus, peptic ulcer disease and gastric cancer. The role and the level of acid (pH levels) in patients presenting with these symptoms has been poorly defined in previous studies since they have used catheter based pH systems which provided recordings only for 24 hours, at only a single location in the esophagus or stomach, and has been associated with patient discomfort leading to inconsistent results. This pilot project will attempt to study the level of acid exposure in the distal esophagus and proximal stomach of patients and correlate it with their symptoms.