Although auditory sensation appeared immediately after device activation, a period of 6 months was necessary for relearning and adaptation of the central auditory system to the altered form of auditory information presented by the auditory brainstem implant.

In patients with a totally obliterated cochlea, the number of intracochlear electrodes can be increased by use of the Nucleus double array implant. As a result, patients achieve significantly better auditory results.

It was concluded that the auditory brainstem implant is an effective support for receiving and, to some degree, differentiating environmental sounds, and that as an adjuvant to lip-reading, it enhances speech perception, especially in quiet surroundings. A comparison between the results of this study and the results of the audiologic tests presented in Part I of this study (published earlier) revealed that patient satisfaction was not directly correlated with the results of the objective auditory tests. In general, patients' judgments of their individual hearing and communication abilities usually rated higher than could have been predicted by the objective audiometric data.

The additional apical array leads to significant improvement in auditory performance in patients with obliterated cochleae by increasing the number of intracochlear electrodes. Despite reduced pitch discrimination, the apical array provides important information for speech recognition. For this reason the Double Array provides a profound advantage for patients with obliterated or surgically inaccessible cochleae.

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