Inclusion Criteria:  Adult patients undergoing sedation with dexmedetomidine during spinal anesthesia for surgery with an estimated time of 90 minutes or longer  Exclusion Criteria:  ASA physical status classification 3-4 Patients with hearing loss or using hearing aids Patients who received narcotic analgesics or sedative drugs within 1 week Patients with alcohol dependence or drug dependence Patients with drug hypersensitivity to dexmedetomidine Patients with arrhythmia, cardiovascular disease, decreased cardiac function and decreased cardiac output Patients who are judged to be difficult to use sedative drugs due to severe respiratory disease Patients with liver failure Patients with kidney failure or on dialysis Patients judged to be unsuitable for the clinical trial by the researchers Patients whose actual operation time is less than 30 minutes