Incus interposition for reconstruction of the sound conduction mechanism in a deep tympanic cavity can be effectively utilized in both Wullstein Type III and IV tympanoplasties. In the Type III tympanoplasty, in which the incus is interposed between malleus or tympanic membrane and stapes, the average post-operative air-bone gap approximates 16 db, while incus placement on the stapes footplate results in an air-bone gap of 23.5 db. There is no difference in change of bone conduction when all operative mehtods are compared. Improved results in reconstruction of the second conduction mechanism are best obtained by conserving or reconstructing the tympanic membrane and posterior bony external canal wall through improved audio-physiologic dynamics.