The study is a single blinded randomized control trial. Participants were blinded to the purpose of the study and to the level of noise they would be exposed. Anesthesiology residents and certified anesthesiologists were recruited.The goal of this study was to measure the time needed to initiate treatment(TNIT) of a severe bradycardia while performing a spinal anesthesia in a high-fidelity simulation environment with either a low or a high ambient dB-level.

Sample size To the investigators' knowledge, no similar study was done and predicting the difference in reaction time depending on level of noise is difficult. In comparable studies, sample size is small. The investigators then used a convenience sample based on the number of residents and staffs anesthesiologists who agreed to participate; the number of participants in this study exceeds the number of participants in previous research. Using the t value and the degrees-of-freedom of the unpaired t-test, the investigators calculated the effect size (r) to characterize the magnitude of the effect and evaluate if the sample size is enough to answer the research hypothesis. An r value of around 0.2 was considered a "weak" effect, 0.5 "medium", and 0.8 "strong". We recruited 15 participants in each group.

Simulation scenario The scenario was performed in situ in an operating room of the investigators' tertiary care hospital. It consisted of doing a spinal anesthesia for a 61 years old woman for a total hip replacement. She was known for stable asthma, high blood pressure and dyslipidemia. Upon entering the room, the anesthesiology evaluation and signed consentment were already completed. A simulated patient with a lumbar puncture simulator fixed on its back (Kyoto Kagaku M43B Lumbar Puncture Simulator II ®) was in position on the operating table for the technique. A simulated anesthesiology nurse was also present in the room. Standard monitoring with EKG, pulse oximeter, non invasive blood pressure were projected on a remotely controlled monitor with Castle Andersen ApS' SimMon app®. Simulated intravenous access was also already in place with the possibility to inject drugs if needed.

The participant then proceeded to the technique. Upon completion of local anesthesia, a mild auto-resolutive drop in heart rate from 85 to 65 without any other hemodynamic change. This benign change was used to try addressing hyper vigilance which is often happening in simulation scenarios. At the moment of dural puncture, a vasovagal event happened. It consisted of a standardised progressive diminution of the heart rate from 80 bpm to 30 bpm. After 10 seconds, blood pressure would fall to 70/40 with appropriate alarms at standard levels. The simulated patient did not tell its discomfort spontaneously but answered to questions if asked. After appropriate treatment, (putting the patient in dorsal position, administration of vasopressors or parasympatholytics) vital signs normalised in less than 30 seconds. The participant was then assigned to complete a questionnaire in another room.

Data Collection All participants were filmed for further revision. Demographics were gathered with a questionnaire. Collected datas were age, sex, resident or anesthesiologist status, number of years as a certified anesthesiologist or year of residency and if a hearing deficit was previously diagnosed. Participants also rated scenario realism on a 1 to 5 Likert scale.

Noise sensitivity was measured with Weinstein's Noise Sensitivity Scale, a 21-items validated questionnaire

After completion, collected datas were explained to the participants, questions were answered and if needed a more complete debriefing was made.

Inclusion Criteria:

• To be a certified anesthesiologist or anesthesiology resident
• To have at least two months of anesthesiology exposure
• To consent to the study

Exclusion Criteria:

• To refuse to participate
• To have a hearing impairment diagnosis that affected anesthesiology practice.

Participants were blindly assigned to the high dB or low dB group. They were also blinded to the purpose of the study until completion.