The Development of the Nucleus^® Freedom™ Cochlear Implant System

Abstract

Cochlear Limited (Cochlear™) released the fourth-generation cochlear implant system, Nucleus® Freedom™, in 2005. Freedom is based on 25 years of experience in cochlear implant research and development and incorporates advances in medicine, implantable materials, electronic technology, and sound coding. This article presents the development of Cochlear's implant systems, with an overview of the first 3 generations, and details of the Freedom system: the CI24RE receiver-stimulator, the Contour Advance™ electrode, the modular Freedom processor, the available speech coding strategies, the input processing options of SmartSound™ to improve the signal before coding as electrical signals, and the programming software. Preliminary results from multicenter studies with the Freedom system are reported, demonstrating better levels of performance compared with the previous systems. The final section presents the most recent implant reliability data, with the early findings at 18 months showing improved reliability of the Freedom implant compared with the earlier Nucleus 3 System. Also reported are some of the findings of Cochlear's collaborative research programs to improve recipient outcomes. Included are studies showing the benefits from bilateral implants, electroacoustic stimulation using an ipsilateral and/or contralateral hearing aid, advanced speech coding, and streamlined speech processor programming.

Lateralization of Interimplant Timing and Level Differences in Children Who Use Bilateral Cochlear Implants

“…The precurved devices are designed to and sit anatomically closer to the modiolus than the straight-array devices (Cohen et al 2003). The pre-curved devices also contain 22 half-banded platinum electrodes, which are thought to reduce the current required to achieve similar levels of loudness as compared to the fully banded electrodes in the straight array (Cohen et al 2003;Patrick et al 2006). The 24M, CS and CA devices use slightly different conversions between clinically used Current Units (CU) and current µA than does the N24RE, leading to some differences in µA delivered by the same CU.…”

Electrical Stimulation of the Midbrain for Hearing Restoration: Insight into the Functional Organization of the Human Central Auditory System

“…Parameters were selected based on various psychophysical tests and device limitations that will be further discussed in a separate publication. Further details on the processor are provided by Patrick et al (2006). monopolar (MP1ϩ2) return path was through both the plate electrode attached to the receiver-stimulator implanted in a bony bed in the skull behind the ear (temporoparietal area) and a ball electrode placed within the temporalis muscle.…”

“…The AMI system consists of similar components (i.e., microphone, processor, telemetry interface, and current stimulator) as the Nucleus Freedom CI systems (Cochlear Ltd.). A review of the Nucleus CI systems has been provided by Patrick et al (2006). The array is 6.2 mm long with a diameter of 0.4 mm.…”

“…The stimulation parameters and active sites are provided in Table 1. Basically, sound (i.e., live voice or environmental sounds during testing and training, or sounds from daily use) was inputted through a microphone attached to the patient's behind-the-ear processor and processed using standard CI strategies (i.e., ACE or SPEAK) (Nucleus CI system; Cochlear Ltd.) (Patrick et al, 2006). The sound was bandpassed filtered into N number of channels in which N corresponded to the number of active sites.…”

Cochlear Implants in Children: A Review

“…The development of speech processing technology in the Cochlear device, which retains a dominant international market share of around 70% (Patrick et al, 2006) will be discussed as an example of this progress. In the early Nucleus 22-channel cochlear implant device, speech feature extraction schemes that presented only the fundamental frequency of speech and the first two formants (or bursts of energy) of speech (F0F2 and F0F1F2) were used (Clark et al, 1983).…”