A method to record drilling noise during skull surgery for the development of noise-reducing assistance systems

Bone surgery on the skull generates substantial structure-borne noise, which can lead to temporary or permanent hearing threshold shifts in patients due to transmission through bone and air conduction. This study investigates the relationship between drilling parameters and resulting noise exposure during cranial bone drilling. To minimize variability and improve reproducibility, all tests were conducted by a single surgeon using both bone substitute material and human donor specimens. Accelerometers and dynamic force sensors were employed to capture vibration and contact force data. The experimental setup successfully correlated acceleration and force signals with airborne sound, enabling insights into patient-experienced noise. Surprisingly, the variability of measurement results in synthetic bone material was comparable to that in human samples, highlighting its practicality but also its limitations. Bone density showed no significant influence on noise levels in cortical bone. Approximately one-third of drilling noise variance could be explained by controllable parameters - drill speed, diameter, and applied force - each contributing nearly equally. Cortical bone samples enabled clearer differentiation of factors due to repeated measurements. All tests were performed without irrigation to isolate drilling noise. Results underscore the potential for integrating real-time sensor feedback into surgical tools to monitor and reduce intraoperative noise exposure. Future work will focus on further standardization using robot-assisted drilling and expanding tests to spongy and aerated bone structures.