Evaluation of the usefulness of a silicone tube connected to a microphone in monitoring noise levels induced by drilling during mastoidectomy and cochleostomy.

Conclusion: The use of a silicone tube and a microphone enables peroperative noise recordings in cadavers and should be safe to apply in vivo. Our preliminary data indicate that noise levels during inner ear surgery reach levels that can cause noise-induced hearing loss. Our method is easily performed and enables future uncomplicated and safe noise recordings and we suggest future application in vivo to expand knowledge regarding peroperative noise levels.

Objectives: To evaluate the safety and utility of a silicone tube connected to a microphone probe in noise recordings during middle ear surgery and to achieve preliminary results regarding drill-related noise levels.

Methods: Peroperative noise recordings were obtained during mastoidectomy and at the round window during cochleostomy in a cadaver model by means of a silicone tube connected to a microphone and a Matlab(®) computer program.

Results: Our method enabled recordings of radiated noise levels close to the drill ranging from 84 to 125 dB SPL during drilling in cortical bone and from 85 to 117 dB during drilling in the mastoid cavity. During cochleostomy noise levels ranged from 114 to 128 dB SPL when recordings were made close to the round window. Maximal noise levels were underestimated due to microphone overload above 80 Pa.