Introduction: Pure-tone audiometry is internationally standardized by ISO 8253-1 "Acoustic-Audiometric test methods—Part 1: Pure-tone air and bone-conduction audiometry." It revised its edition in 2010, and there was the introduction of Annexure A recommending the estimated measurement uncertainly because audiometry is influenced by parameters such as repeatability , audiometer performance , transducers fitting, environment noise, masking, experience of the examiner, cooperation of the subject, and situations difficult to measure.