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The emerging research is positive and suggests that CIs
offer partial hearing restoration for the implanted ear,
although outcomes related to binaural hearing are
mixed. Speech recognition in the ear implanted, when
measured in quiet, has been shown to improve signifi-
cantly following implantation.
10,11
Speech recognition in
noise, however, is highly variable and test parameters
vary considerably among investigators, making direct
comparison difficult. For example, Vermiere, Tavora-
Viera, and Stelzig each presented speech and noise from
a front center speaker (S0N0) and used an adaptive pro-
cedure to find the signal-to-noise ratio (SNR) needed for
50% correct, although speech materials varied among
them.
10,12,13
Vermiere et al. found a statistically signifi-
cant decrease in the SNR needed for sentence under-
standing, and the other two did not.
10
Later, a meta-
analysis pooling all three studies demonstrated a mean
decrease in SNR necessary for 50% correct.
14
In other
research, Stelzig et al. and Arndt et al. each presented
speech and noise at 65-dB sound pressure level (SPL)
from S0N0 and found no difference in sentence recogni-
tion following cochlear implantation.
13,15
Zeitler et al.
showed subjects undergoing CI for SSD demonstrated
significant improvement in sentence scores in complex
noise environments in the binaural condition, with the
greatest improvements when speech is presented to the
implanted ear. These same subjects also showed signifi-
cant improvements in sound source localization, with
some subjects localizing sound at or near the accuracy of
normal hearing listeners.
16
Other studies have also
reported significant improvement for localization among
patients with SSD, decreased tinnitus, and improved
self-perceived benefit on the Speech Spatial and Qual-
ities of Hearing questionnaire.
17
Reports of tinnitus suppression after implantation
have been reported by several investigators.
15,18
In one
study, Arts et al. examined the impact of implantation
on tinnitus among patients with SSD by pooling data
from several reports.
18
The data were treated as a multi-
center study and subjected to matched
t
tests. Results
demonstrated improved tinnitus between preoperative
and 1-, 3-, 6-, and 24- month postoperative test intervals.
The purpose of this study was to complete a preliminary
evaluation of speech recognition in quiet and in noise
among a group of adults and children with SSD. Data
was compiled from two separate centers.
MATERIALS AND METHODS
The current study was a multisite, single-arm repeated
measures research design. Each participating center obtained
institutional review board approval from their respective center.
Participants
The participants in this study had mild to severe sensori-
neural hearing loss with 40% consonant-nucleus-consonant
(CNC) word recognition on the affected side. A pure tone aver-
age of 30 dB HL or better and a mean word recognition score of
99.3% (standard deviation [SD] 2.8%) were present on the con-
tralateral side. Thus, all patients had truly normal hearing in
the nonimplanted ear. The preoperative air conduction hearing
thresholds for the ear implanted can be found in Figure 1.
The total sample was comprised of 23 individuals (17
adults, 6 children). The adults ranged in age from 31 to 62
years, and the children ranged in age from 5 to 15 years. Dura-
tion of hearing loss was defined as the time between onset of
hearing loss and time of implantation. Duration of hearing loss
ranged from 0.5 to 9.5 years with an average of 4.0 years. In
all, there were 10 left ears and 13 right ears implanted. Demo-
graphic information for all participants can be found in Table I.
Materials
Speech understanding was assessed using the CNC word
test and the AzBio sentence test.
19,20
The CNC word test is com-
prised of 10 lists, each containing 50 monosyllabic words produced
by a single male talker. The AzBio Sentence Test is comprised of
15 lists of 20 sentences, each produced by two male and two
female talkers and scored for each word repeated correctly.
Procedures
Prior to preoperative aided testing, participants’ hearing
aids were set to National Acoustic Laboratories (prescriptive
targets).
21
Participants who did not use hearing aids on a full-
time basis were required to complete a 30-day trial before CI
candidacy determination.
Fig. 1. Preoperative air conduction hearing thresholds for the implanted ear.
Sladen et al.: Cochlear Implantation for SSD
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