Iowa/Nucleus 10/10 mm and Nucleus Freedom Cochlear Implants Implanted Bilaterally in Children Ages 12-24 Months

The study will be conducted as a repeated-measure , single-subject experiment. A single- subject research design (in which each participant serves as his or her own control) is appropriate because it accommodates the heterogeneity that characterizes hearing- impaired population s. Blinding or masking procedures are not included in the design, as it is not possible to conceal the presence or absence of a cochlear implant from device recipients and/or clinical investigators.

Preoperatively , candidates will be assessed with their current amplification to evaluate their appropriateness for entrance into the study. The candidates' audiometric configuration must meet the above inclusion criteria. That is, the candidate must have a severe-to-profound sensorineural hearing loss from 250 to 8000 Hz. Prior to testing, the appropriateness of the hearing aid fitting will be assessed and adjustments made if necessary. In cases where amplification has not been used for more than one year, new hearing aids will be fit, worn for a minimum three-month trial and the participants re- evaluated to confirm continuance with the study.

Participants will receive one standard Nucleus Freedom electrode array and an Iowa/Nucleus 10/ 10 mm electrode array on the contralateral side. Half will be implanted with the 10 mm electrode array on their right side and half will be implanted with the 10 mm electrode array on their left side. We will alternate every other subject between the right and left ears. Postoperatively, Iowa/Nucleus 10110 mm electrode alone, standard Freedom electrode alone, and bilateral listening (i.e., Iowa/Nucleus 10/ 10 mm and standard electrodes together) modes will be compared with repeated testing through five years of age of the child. These comparisons will help to evaluate the effects of bilateral stimulation using different cochlear implant devices while possibly preserving the scala media, organ of Corti, and supporting cells for future advances in the ear receiving the Iowa/Nucleus 10/ 10 mm electrode device. In addition, we will attempt to compare these results with age-matched unilaterally implanted children tested on the same speech perception and speech/language measures. In addition, if possible, we will attempt to compare speech perception and speech/language measures on age-matched children with bilateral standard long electrode arrays in both ears. The following defines the various modes referenced throughout the course of this text:

Iowa/Nucleus 10/10 mm Electrode Array: The Iowa/Nucleus 10/ 10 mm electrode array was designed to reduce the incidence of intracochlear injury and developed by the Iowa Cochlear Implant Team and Cochlear Americas. This array was designed to preserve the scala media, organ of Corti and supporting cells of the implanted ear for future advances in molecular and/or genetic treatments of the inner ear. This investigational device is very

similar to the Nucleus Hybrid-6 (formerly known as CI24RE Hybrid), the subject ofIDE No. 0990155. See ATTACHMENT 1 for a letter from the Sponsor ofIDE No. 0990155 authorizing the FDA to review the information in IDE No. 0990155 for purposes of the current IDE application. Like the Hybrid-6, the Iowa/Nucleus 10/ 10 mm cochlear implant is 0.2 mm x 0.4 mm in diameter and has a short, 10 mm electrode array that it is inserted only into the more basal region of the cochlea. In comparison to the Hybrid-6, the Iowa/Nucleus 10/ 10 mm cochlear implant has a total of 10 contacts, or 4 more than the 6 contacts/channels present on the Hybrid-6. The contacts are spaced closer together and occupy approximately 6 mm of the apical segment of the 10 mm array.