Acid reflux and heartburn are the common name for gastroesophageal reflux disease (GERD), which is defined as chronic symptoms or mucosal damage produced by the abnormal reflux of stomach acid to the esophagus.  It is usually caused by the loosening of the lower esophageal sphincter.  Another form of reflux produces resp[iratory and laryngeal issues is laryngopharyngeal reflux (LPR).  It is unlikely to cause heartburn and sometimes is called silent reflux.