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.

Operating room (OR) noise is a common but underestimated environmental factor that may affect both patients and medical staff. In patients under general anesthesia, excessive noise may influence depth of anesthesia, physiological stability, and recovery outcomes.This prospective observational study will investigate the correlation between intraoperative noise levels and bispectral index (BIS) values, as well as hemodynamic parameters (systolic, diastolic, and mean arterial pressure, and heart rate). Seventy adult patients undergoing elective surgery under general anesthesia will be monitored. Noise levels will be measured every 10 minutes with a calibrated sound level meter (CEM DT-8850), while BIS and hemodynamic parameters will be recorded at 10-minute and 5-minute intervals, respectively. Additionally, the type of noise (device-related, human-related, alarms, media) and the surgical branch (classified into high, moderate, or low noise categories) will be documented. Data will be analyzed to determine whether environmental noise correlates with BIS fluctuations and hemodynamic stability. The study is observational only and involves no intervention beyond standard anesthesia practice. Results are expected to raise awareness of environmental influences on anesthesia management and provide recommendations for OR organization to enhance patient safety.

Inclusion Criteria:

• Adults aged 18-70
• ASA (American Society of Anesthesiologists) physical status score I-II
• Scheduled for elective surgery
• To be undergoing general anesthesia
• Having signed the informed consent form to participate in the study

Exclusion Criteria:

• Hearing impairment or ear pathology
• History of neurological disease (epilepsy, stroke, dementia, etc.)
• Use of psychiatric medications (anxiolytics, antidepressants, antipsychotics, etc.)
• Indications for emergency surgery
• Planned spinal or epidural anesthesia
• Conditions unsuitable for BIS monitoring
• Cognitive impairment preventing informed consent

Adult patients aged 18-70 years undergoing elective surgery under general anesthesia at Başakşehir Çam and Sakura City Hospital will be included. Eligible participants must have ASA physical status I-II, be cognitively able to provide informed consent, and scheduled for surgeries lasting up to 2 hours. Both male and female patients will be enrolled without restriction. Only elective (non-emergency) procedures are considered. Surgeries from multiple specialties (orthopedics, neurosurgery, cardiovascular, general surgery, gynecology, urology, ophthalmology, otolaryngology, plastic surgery, dermatology) will be included, representing high, moderate, and low noise exposure categories.

Individual participant data (IPD) will not be shared due to privacy and confidentiality concerns. Only aggregated results will be published in scientific journals and conferences.