Validation of a Multimodal Indicator of Depth of Anesthesia

Inclusion Criteria: * age ≥ 18 years * elective surgery under general anesthesia * anticipated operating time of about one hour or longer * ASA physical status I-III * written informed consent Exclusion Criteria: * chronic intake of CNS affecting drugs * alcohol or drug abuse in the last three months * CNS or psychiatric disease * hardness of hearing or deafness * abnormal gastrointestinal motility * non-adherence to fasting guidelines, emergency surgery * anticipated difficult airway * pregnancy * cardiac surgery and surgery involving the head and/or neck * postoperatively prolonged intubation * pre- and/or postoperative intensive care treatment