Keywords: Key words: event-related potentials, P300, cognition, auditory.

Abstract: Summary Introduction: Evaluation of the hearing function in individuals wearing electronic hearing aids is very important for the rehabilitation process. However, in these subjects, the procedures should be conducted under free field. Objective: To analyze the applicability of the P300 cognitive potential investigated under free field. Material and Method: Thirty-three subjects of both genders were evaluated, who aged 7 to 34 years and presented normal hearing and at no risk for mental disturbances. The P300 cognitive potential was accomplished with aid of the equipment Biologic's Evoked Potential System (EP), with insertion phones (3A) under free field (0º Azimuth and 45º Azimuth). Results: There was no statistically significant difference for the latency of N2 and P300 and amplitude of P300 with regard to gender and means for accomplishment of the test (phone and free field), as well as for comparison of the measurements under free field at 0º and 45º Azimuth. Conclusion: Investigation of the P300 cognitive potential under free field is a viable procedure.