Hybrid Cochlear Implants in Severe to Profound Adults, Children, and Adolescents

The purpose of this study is to determine if individuals with residual low-frequency hearing
in the severe range can develop improved speech perception by combining their residual
acoustic hearing with electrical processing through a cochlear implant designed to stimulate
the high-frequency basal and middle turn of the cochlea while preserving useful low-frequency
acoustic hearing. To accomplish this, we propose to implant individuals with severe hearing
with a Cochlear® Nucleus™ Hybrid L24 Implant or a Cochlear® Nucleus™ Hybrid S12 in the poorer
ear. We believe these devices will do less damage to the Organ of Corti structures, than
longer, more invasive standard cochlear implant electrodes.

Two different populations will be studied under this IDE.

Population 1: 15 Adults who have a severe sensorineural hearing loss with a pure-tone average
(PTA) between 60-90 decibels (dB) hearing level (HL) between 125-1500 Hz and profound loss at
higher frequencies will be implanted with the Cochlear® Nucleus™ Hybrid L24 Implant. The
potential subject will present with Consonant-Nucleus-Consonant (CNC) monosyllabic word
scores between 0-35% in the ear to be implanted and up to 60% understanding in the
contralateral ear in the best-aided condition.

Population 2: 30 Children (ages 5-12 years) and adolescents (ages 13-15 years) who have a
sensorineural hearing loss with a pure-tone average (PTA) between 60-90 dB HL between
125-1500 Hz and profound loss at higher frequencies will be implanted with the Cochlear®
Nucleus™ Hybrid L24 Implant or the Cochlear® Nucleus™ Hybrid S12 Implant. Those that have
hearing thresholds between 60-90 dB HL at 1500 Hz would be implanted with the less invasive
shorter 10 mm Hybrid S12 in attempt to better preserve the middle frequency range. Those with
hearing thresholds >90 dB HL at 1500 Hz would receive the longer 16 mm Hybrid L24 electrode.
The potential subject will present with Phonetically Balanced Kindergarten (PB-K)
monosyllabic word scores between 0-50% in the ear to be implanted and up to 60% understanding
in the contralateral ear in the best-aided condition.

Through the preserved acoustic hearing, we believe the subject will experience better signal
to noise ratios for speech perception in noise, better localization of sound and an
improvement music perception. Histological evidence from patients implanted with standard
arrays and our experience with a short electrode array for implantation of individuals with
significant residual hearing both support this assumption (Nadol, Shiao, Burgess, Ketten,
Eddington et al., 2001). The duration of this study will be 2 years (24 months) for adults
and for 5 years (60 months) in children and adolescents.

Inclusion Criteria:

1.1 Criteria for Inclusion in Population 1

Criterion for selection will be subject interest in preservation of residual hearing;
severe sensorineural hearing loss; lack of benefit from appropriately fit binaural hearing
aids worn on a full-time basis; and realistic expectations. Qualified participants must
also meet the following criteria for inclusion:

1. Eighteen year of age or older at the time of implantation.

2. Severe sensorineural hearing loss with a pure-tone average (PTA) between 60-90 dB HL
between 125-1500 Hz and profound loss at higher frequencies in the ear to be
implanted.

3. Speech Perception:

- The Consonant-Nucleus-Consonant (CNC) word recognition score between 0% and 35%
inclusive in the ear to be implanted.

- The CNC word recognition score in the contralateral ear equal to or better than,
in the ear to be implanted but not more than 60% in the best-aided condition.

4. English spoken as a primary language.

5. Willingness to comply with all study requirements.

6. Minimum of 30 day hearing aid trial with appropriately fit hearing aids worn on a
full-time basis (8 hours per day).

7. Patent cochlea and normal cochlear anatomy.

1.2 Criteria for Inclusion in Population 2

Criterion for selection will be parent interest in preservation of residual hearing; severe
post-lingual onset of sensorineural hearing loss; lack of benefit from appropriately fit
binaural hearing aids worn on a full-time basis; and supportive family dynamics. Qualified
participants must also meet the following criteria for inclusion:

1. Five to fifteen years of age at the time of implantation.

2. Severe sensorineural hearing loss with a pure-tone average (PTA) between 70-90 dB HL
between 125-1500 Hz and profound loss at higher frequencies in the ear to be
implanted.

3. Speech Perception:

- The Phonetically Balanced-Kindergarten (PB-K) word recognition score between 0%
and 50% inclusive in the ear to be implanted.

- The PB-K word recognition score in the contralateral ear equal to or better than,
in the ear to be implanted but not more than 60%.

4. English spoken as a primary language.

5. Willingness to comply with all study requirements.

6. Minimum of 30-day hearing aid trial with appropriately fit hearing aids worn on a
full-time basis (8 hours per day)..

7. Patent cochlea and normal cochlear anatomy.

8. Must be in a habilitation/educational program with an emphasis on spoken language
development.

Exclusion Criteria:

1.3 Criteria for Exclusion in Populations 1 and 2

1. Medical or psychological conditions that contraindicate undergoing surgery.

2. Ossification or any other cochlear anomaly that might prevent complete insertion of
the electrode array.

3. Unrealistic expectations on the part of the candidate and/or candidate's family,
regarding the possible benefits, risks, and limitations that are inherent to the
surgical procedure(s) and prosthetic devices.

4. Unwillingness or inability of the candidate to comply with all investigational
requirements.

5. Active middle ear infection.