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Drill- and suction-generated noise in mastoid surgery.

The air-conduction noise levels in the external and middle ear generated by drilling and suction during temporal bone surgery were measured. Variables included diamond burrs, cutting burrs, two different air drills (Hall and Stryker) an electric drill (Emesco), and drilling with and without suction irrigation. The results show that the single factor contributing the highest noise level is suction irrigation, which exposes the ipsilateral ear to noise levels averaging up to 107 dB (A). The average noise levels of drilling range from 65 to 96 dB (A) varying with the drill and burr used. Simultaneous drilling and suction irrigation generated noise levels ranging from 91 to 108 dB (A). Cutting burrs were found to be up to 9 dB (A) more intense than diamond burrs. Exposure to these noise levels may account for shifts in the hearing thresholds sometimes apparent in postoperative audiograms of mastoid surgery patients.