<p class="abstract"><strong>Background:</strong> Bone drilling and suction during surgeries, exposes cochleae to noise of markedly high levels, temporal bone vibrations to high speeds of drill bits. Variations in burr type and drilling duration can determine extent of noise generated. These may affect cochlea and hearing status of a patient. This study tries to identify hearing loss if any, in the apparently healthy contralateral ear and, the effect of various drill parameters on hearing status in patients with chronic otitis media following mastoidectomy surgery.</p><p class="abstract"><strong>Methods: </strong>Study done using proforma, clinical examination data from operation theatre during surgery and audiology department. Pure Tone Audiometry of apparently healthy contralateral and diseased ears in patients done before surgery, within 24 hrs and 72 hrs after surgery.</p><p class="abstract"><strong>Results:</strong> Out of 161 patients ,12 patients (7.45%) developed hearing loss post operatively. The mean duration of drilling with cutting burr in the 12 patients with hearing loss was 28 minutes 20 seconds (SD: 1.72) and for diamond burr was 25 minutes and 26 seconds (SD: 2.06). Among the patients with hearing loss, four had multiple frequencies affected (33.3%). There was a statistically significant relation in type of drills used in surgery and hearing loss (p&lt;0.001). In 10 Out of 12 patients, the hearing loss post-surgery, (83.3%) reverted to normal within 72 hrs.</p><p class="abstract"><strong>Conclusions: </strong>A positive correlation exists between, transient sensorineural hearing loss that develops post-surgery with the various type of drills used for surgery, which reverted to pre-operative hearing levels within 3 days.</p><p class="abstract"> </p>