Auditory abilities after cochlear implantation in adults with unilateral deafness: a pilot study

Abstract

Objective: This pilot study examined speech recognition, localization, temporal and spectral discrimination, and subjective reports of cochlear implant (CI) recipients with unilateral deafness.

Study design: Three adult male participants with short-term unilateral deafness (<5 yr) participated. All had sudden onset of severe-to-profound hearing loss in 1 ear, which then received a CI, and normal or near normal hearing in the other ear. Speech recognition in quiet and noise, localization, discrimination of temporal and spectral cues, and a subjective questionnaire were obtained over several days. Listening conditions were CI, normal hearing (NH) ear, and bilaterally (CI and NH).

Results: All participants had open-set speech recognition and excellent audibility (250-6,000 Hz) with the CI. Localization improved bilaterally compared with the NH ear alone. Word recognition in noise was significantly better bilaterally than with the NH ear for 2 participants. Sentence recognition in various noise conditions did not show significant bilateral improvement; however, the CI did not hinder performance in noise even when noise was toward the CI side. The addition of the CI improved temporal difference discrimination for 2 participants and spectral difference discrimination for all participants. Participants wore the CI full time, and subjective reports were positive.

Conclusion: Overall, the CI recipients with unilateral deafness obtained open-set speech recognition, improved localization, improved word recognition in noise, and improved perception of their ability to hear in everyday life. A larger study is warranted to further quantify the benefits and limitations of cochlear implantation in individuals with unilateral deafness.

Figure 1

CNC word scores in quiet for the CI and NH ear and bilaterally for P2 (panel A). CNC word scores in noise (−2 dB SNR with four-talker babble) for the NH ear and bilaterally (panel B). Asterisks denote significant differences (p < 0.05).

Figure 2

Participants' localization results for the three listening conditions, CI, NH ear, and bilaterally. For each plot, the x- and y-axes represent the locations of the stimulus and the participants' responses to the stimulus, respectively. The RMS error, in degrees, is indicated in the upper left hand corner of each plot. Asterisks denote significant differences between the NH ear and bilaterally (p < 0.001).

Figure 3

Participants' mean SNR-50 obtained for each listening condition for the BKB-SIN test when sentences were presented from the front loudspeaker and noise was presented from the front (panel A), from the left (panel B), and from the right (panel C).

Figure 4

Participants' average SNR-50 obtained for the HINT in the R-SPACE for each listening condition.

Figure 5

Participants' mean JNDs for Temporal (panel A) and Spectral (panel B) RSS stimuli are displayed for test runs 1 through 4 and the three listening conditions. Data from NH adults are shown in gray (mean and +/− 1SD).

Figure 6

Participants' mean SRTs are displayed in quiet and noise (noise to CI, noise to NH, noise front) for the three listening conditions. Data from NH adults are shown in gray (mean and +/− 1SD).

Figure 7

Participants' average rating across test items for each SSQ scale. P1 and P3 completed the SSQ as they would have prior to obtaining a CI (NoCI). P1–P3 completed the SSQ as they currently hear with the CI and NH ear (CI). The plus symbols denote “benefit” as described by Noble and colleagues (30).