This prospective observational study aims to evaluate the impact of operating room noise on bispectral index (BIS) and hemodynamic parameters in patients undergoing general anesthesia. Environmental noise in operating rooms, often overlooked, may influence anesthesia depth, patient safety, and physiological stability. A total of 70 adult patients (ASA I-II, 18-65 years, elective surgery under general anesthesia) will be enrolled at Başakşehir Çam and Sakura City Hospital. Patients will be categorized into two groups based on intraoperative average noise levels: noisy group (\>65 dB) and quiet group (\<55 dB). Noise levels will be measured every 10 minutes using a CEM DT-8850 sound level meter, BIS will be recorded every 10 minutes, and hemodynamic variables (systolic, diastolic, mean arterial pressure, and heart rate) will be recorded every 5 minutes.
Primary outcome is the correlation between mean intraoperative noise levels (LAeq) and BIS values during the maintenance phase of anesthesia. Secondary outcomes include the relationship between noise characteristics (e.g., device-related, human-related, alarms, media) and hemodynamic stability, as well as surgical branch-related noise classifications (high, moderate, low). The study is non-interventional, with no additional risk to participants beyond standard clinical monitoring. Findings are expected to provide evidence on the role of environmental noise in anesthesia quality, inform operating room organization, and contribute to patient safety improvements.