An in-situ calibration procedure for click stimuli

The use of insert earphones for delivering acoustic signals to subjects and patients has grown in popularity in auditory research and clinical audiology. In conjunction with transducer characteristics, the insertion of an earphone into the ear canal modifies ear canal acoustics and results in an acoustic signal in the ear canal unlike the original signal delivered to the earphone. The modified ear canal signal will differ within and between individuals depending on the depth of earphone insertion and ear canal geometry. We describe a new procedure for correcting earphone and ear canal acoustics. When applied to the calibration of click stimuli, the resultant ear canal signal in each individual is an impulse with a spectrum almost identical to the rectangular pulse delivered to the transducer.