Effect of tympanic perforations on the detection of distortion-product otoacoustic emissions.

The detection of distortion-product otoacoustic emissions (DPOAEs) depends on the viability of the ear's conduction apparatus. However, tympanic membrane perforations and other conductive disorders have not been fully investigated with regard to the examination of DPOAEs. Using the guinea pig model, we made perforations of different sizes and loci on the tympanic membrane and collected DPOAEs data for frequencies between 2,193 and 5,508 Hz for each condition. We found that small perforations, up to 25% of the area of the tympanic membrane, still allow us to detect emissions at the specified frequencies. However, perforations of 50% and larger, as well as those accompanied by traumatic perilymph fistulas and ossicular disarticulations, severely interfered with the detection of DPOAEs. We discuss the clinical relevance of these findings with respect to the potential uses of DPOAEs.