Implications of sound levels generated by otologic devices

Exposure to loud noise can result in sensorineural hearing loss. In otology, a wide variety of devices are used that have significant noise output, both to the operator and the patient. This study quantifies and compares the sound pressure levels (SPL) of a variety of otologic instruments.

Using a calibrated sound pressure level meter, the peak and impulse sound pressure levels of several otologic instruments were determined at 1 cm from their application to human temporal bones. Devices measured were an air-powered drill with a cutting burr, an electric micro-drill, and KTP, CO(2), and erbium lasers.

Impulse sound pressure levels for the KTP laser, CO(2) laser, microdrill, air-powered drill and erbium laser were 67, 71, 90, 105, and 105 dBA, respectively. Peak sound pressure levels were 81, 89, 102, 118, and 132 dBA, respectively.

Use of the KTP laser, CO(2) laser, and microdrill result in impulse levels of less than 100 dBA. Although the impulse levels of the erbium laser and the air-powered drill were equivalent, the peak sound pressure levels of the erbium laser were significantly higher. These high sound pressure levels may increase the chance for hearing loss. Like any tool, lasers and drills have benefits and risks. The results of this study demonstrate significant differences in SPLs of common otologic lasers and drills. Although noise-induced hearing loss is a function of both SPL and duration of exposure, surgeons should consider these differences when selecting and applying these tools, especially when used on or adjacent to the ossicular chain and stapes footplate.