Hearing loss has been reported as a complication following cardiac surgery with extracorporeal circulation. Preoperative hearing testing is not commonly done in these procedures, so preoperative and postoperative hearing loss, if any, may occur unnoticed. 30 subjects in the age range of 50–70 with a mean age of 60.16 years with myocardial infarction and scheduled to undergo cardiopulmonary bypass surgery underwent detailed audiological assessment comprising of pure tone audiometry with extended high frequency audiometry, speech audiometry and otoacoustic emissions (OAE) testing. The audiological testing was done preoperatively and at 2 weeks after the surgery. On pure tone audiometry, the difference between pre- and postsurgery mean values for both ears at 10, 12, and 16？KHz showed highly significant differences ( ). On OAE testing, a significant difference ( ) between pre- and postvalues of signal to noise ratio (SNR) was found. It is hypothesised that CPB surgery makes blood redistribution to other organs easy, deviating from internal ear, which is highly susceptible as it lacks collateral circulation and its cells have high energy metabolism. Epithelial damage on internal ear microcirculation causes reduction of the cochlear potentials and hence hearing loss. 1. Introduction Hearing is one of the most significant of human senses. For an individual, it is perhaps the most crucial link in communication with the outside world. It is a prerequisite for fulfilling life and career. Any deficit in it is as frightening for the person as a loss of vision. It is a handicap potentially severe enough to deny a person a normal life and livelihood [1]. Various etiologies have been proposed to explain the sudden sensorineural hearing loss (SSNHL) in the general population and include inflammatory, vascular, metabolic, traumatic, membrane rupture, functional, or idiopathic [2]. In recent decades, the development of SSNHL with nonotologic surgeries carried out under general anesthesia has become a great area of interest. A considerable majority includes cardiopulmonary bypass procedures, an association that has long been recognised [3]. Cardiopulmonary bypass (CPB) is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining the circulation of blood and the oxygen content of the body. Cardiopulmonary bypass surgery is a common practise in many medical centres, and instances of unilateral hearing loss in these patients have been reported. The first report of this kind was made by Arenberg et al. [4] who reported sudden
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